Global Degradation of Soil and Water Resources: Regional Assessment and Strategies [1st ed. 2022] 9789811679155, 9789811679162, 9787030627872, 9811679150

Table of contents :
Preface
Contents
Book_CON_Heading
Introduction—Overview of Global Soil and Water Stress
Introduction of the First Authors
1 Probabilistic Land Use Allocation in the Global Soil Erosion Modelling
Abstract
References
2 Soil Erosion and Its Impacts on Greenhouse Gases
2.1 Introduction
2.2 Climate Change and the Soil Erosion Risks
2.3 Fate of Carbon Transported by Erosional Processes
2.4 Burial of Sediment-Laden SOC
2.5 Erosion-Induced Gaseous Emissions
2.6 Forms of Soil Organic Carbon and Decomposition During Erosion
2.7 Wind Erosion and CO2 Emissions
2.8 Implications to Carbon Budgeting and Modelling
2.9 Conclusion
References
3 Assessing Multiple, Concurrent and Interactive Land and Soil Degradation Processes
3.1 Introduction
3.2 How Scarce are Productive Land Resources
3.3 Common Forms of Degradation
3.4 Soil Degradation Lies at the Core of Land Degradation
3.5 Concurrent, Overlapping and Interactive Degradation Processes
3.6 Documentation of Concurrent, Interactive Degradation Processes
3.7 Illustrative Case Studies
3.7.1 Multiple Impacts of Land Clearing
3.7.2 Soil Erodibility-Salinity-Sodicity Interactions
3.7.3 Multiple Impacts of Soil Erosion
3.8 Challenges and Strategies for Assessing Multiple and Interactive Degradation Processes and Impacts
3.9 Important Steps
3.10 Summary
References
African Region
Introduction of the First Authors
4 Agricultural Soil and Water Conservation Issues in East Africa
4.1 Introduction
4.2 Characteristics of East African Region
4.2.1 Climate and Agro-Ecological Zones
4.2.2 Soil Type Diversity and Agricultural Particularities
4.2.3 Agricultural Water Resource Status
4.3 Agricultural Soil Management Issues in East Africa
4.3.1 Soil Threats and Land Degradateion
4.3.2 Salinization and Desertification
4.3.3 Social Barriers and Demographic Constraints
4.4 Agricultural Water Management Issues in East Africa
4.4.1 Impact of Climate Change on Temporal and Spatial Rainfall Distribution
4.4.2 Dry Spell and Droughts
4.4.3 Water Limit and Irrigation Infrast-Ructure Deficiency
4.5 Agricultural Soil and Water Conservation in East Africa
4.5.1 Initiatives in Soil Fertility Management
4.5.2 Existence of Alternative Agronomic Practices
4.5.3 Improvement of Agricultural Irrigation Infrastructures
4.6 Conclusion
References
5 Institutional and Technical Efforts for the Soil and Water Conservation in North Africa
5.1 Introduction
5.2 Institutional Efforts of SWC in North Africa
5.3 Soil Erosion in North Africa
5.3.1 Water Erosion
5.3.2 Wind Erosion
5.4 Soil Conservation Methods Against Water Erosion
5.4.1 Reforestation
5.4.2 Agronomic Practices
5.4.3 Mechanical Structures
5.4.4 Gully Erosion Control
5.5 Integrated Watershed Management: A New Approach
5.6 Technics of Wind Erosion Control
5.7 Conclusions
References
6 Sustainable Use of Soil and Water Resources to Combat Degradation
6.1 Introduction
6.2 Water Resources in Egypt
6.3 Land and Soil Resources
6.4 The Nile Valley and Delta Zone (About 33,000 km2)
6.5 North Coastal Zone
6.6 Inland Sinai and Eastern Desert Zone
6.7 The Western Desert Zone (About 671,000 km2)
6.8 Agro-Ecological Zones of Egypt
6.9 Old Land
6.10 New Land
6.11 Rain Fed Areas
6.12 Major Pressures on Land Resources in Egypt
6.13 Urbanization
6.14 Soil Salinity and Water Logging
6.15 Soil Fertility Depletion
6.16 Pollution
6.17 Land Physical Degradation
6.18 Soil Erosion
6.19 Sand Dunes
6.20 Cost Assessment of Land Degradation
6.21 Egypt Efforts to Combat Land Degradation
6.22 First Trend
6.23 Second Trend
6.24 Legislations
References
American Region
Introduction of the First Authors
7 Long-Term Effects of Different Agricultural Soil Use and Management Systems on Soil Degradation in Uruguay
7.1 Introduction
7.2 Model Estimations of Soil Erosion and SOC Content
7.3 Experimental Results on Rotations and Tillage Systems Previously Reviewed
7.4 Review of Information After 2004
7.4.1 “Old Rotations” Experiment in Exp. Station INIA-La Estanzuela
7.4.2 Forage Production Rotations in Exp. Unit INIA-Palo a Pique
7.4.3 Rotations and Tillage Intensity Interaction Experiment in Exp. Station EEMAC-Fac. Of Agronomy, Udelar
7.5 Crop Productivity Under Different Soil Use and Management Systems
7.6 Summary and Conclusions
References
8 Assessment of the Utility of the Diffusion Model for Facilitating Adoption of Soil and Water Conservation Production Systems in North America
8.1 Introduction
8.2 Organization of Chapter
8.3 The Diffusion Theoretical Perspective
8.4 Application of the Diffusion Model
8.5 Theoretical Perspectives Guiding Recent Research
8.6 Discussion
8.7 Conclusions
References
9 Eight Decades of USDA Soil and Water Conservation Policies and Programs
9.1 Introduction
9.2 Historical Trends in Soil and Water Conservation Policy: Voluntary Incentive Approaches
9.3 A Shift in Conservation Policy: Disincentives
9.4 Future Considerations and Policy Implications
9.4.1 Centralized Policy Approaches
9.4.2 Decentralized Policy Approaches
9.4.3 Hybrid Policy Approaches
9.5 Conclusions
References
10 Market Approaches for Addressing Soil and Water Resources Problems
10.1 Introduction
10.2 Agriculture is a Source of Ecosystem Services
10.3 Markets for Ecosystem Services
10.3.1 Emissions Trading Markets
10.3.2 Linked Markets
10.4 Lessons Learned
10.4.1 Issue: Performance of Management Practices
10.4.2 Issue: Quality Assurance (Standards and Certification)
10.4.3 Issue: Additionality
10.4.4 Issue: Cost of Information
10.4.5 Issue: Bringing Together Buyers and Sellers
10.4.6 Issue: Coordinating Conservation Programs with Markets
10.5 Market-Like Mechanisms
10.6 Conclusions
References
11 Desertification in Argentina: The Causes and Effects on Human Beings
Abstract
11.1 Introduction
11.2 Methodology Used for Land Degradation Assessment in Argentina
11.2.1 The Steps of the Assessment Used at the National Level Were as Follows
11.2.2 Characterization of the Study Areas
11.2.3 Land Use Units
11.2.4 Soil, Vegetation and Water Resource Degradation
11.2.5 Working Frameworks: Driving Forces, Pressures, State, Impacts and Responses (DPSIR), Ecosystem Services (ES) and Sustainable Livelihoods (Fig. 11.10)
11.3 Results and Discussion
11.4 Conclusions
References
Asian Region
Introduction of the First Authors
12 Characterization of Soil and Water Resources in Yemen
12.1 General Background of Yemen Socio-economic Development
12.2 Geographic Sitting
12.2.1 Location, Population and General Topographic Features
12.2.2 Physiographic Regions
12.2.3 Geology
12.2.4 Climate
12.2.5 Vegetation Cover and Plant Species
12.3 Soil Resources
12.3.1 Introduction
12.3.2 History and Status of Soil Survey Programs in Yemen
12.3.3 The Updating National Soil Map
12.3.4 Soil Parent Material
12.3.5 Soil Properties
12.3.6 Soil Classification
12.4 Land Degradation
12.5 Agricultural Land Use
12.6 Water Resources
12.6.1 Surface Water
12.6.2 Groundwater
12.6.3 Causes of the Water Crisis
References
13 Soil Erosion Environment Background and Its Spatial Distribution in China
13.1 Environment Background of Soil Erosion in China
13.1.1 Landform and Soil Erosion in China
13.1.2 Climate and Soil Erosion in China
13.1.3 Soil Environment and Soil Erosion in China
13.1.4 Vegetation and Soil Erosion in China
13.1.5 Impacts of Human Activities on Soil Erosion in China
13.2 Spatial Distribution of Soil Erosion in China
13.2.1 Eastern Soil Erosion Region by Water (I)
13.2.2 Northwestern Soil Erosion Region by Wind (II)
13.2.3 Qinghai-Tibet Plateau Soil Erosion Region by Freeze–thaw (III)
References
14 Water Erosion and Its Control in China
14.1 Changes in Water Erosion
14.1.1 Soil Erosion Surveys in China
14.1.2 Current Status of Water Erosion
14.1.3 Changes in Water Erosion Since the 1990s
14.2 Water Erosion Control
14.2.1 Soil and Water Conservation Measures in China
14.2.2 Soil Conservation Measures in Provinces
14.3 Water Erosion and Its Control Across Regions
14.3.1 Black Soil Region of Northeastern China
14.3.2 Earth-Rocky Mountain Region of Northern China
14.3.3 Loess Plateau in Northwestern China
14.3.4 Red Soil Region of Southern China
14.3.5 Purple Soil Region of Southwestern China
14.3.6 Karst Region of Southwestern China
References
15 Aeolian Desertification Status and Its Control in China
15.1 Introduction
15.2 Aeolian Desertification Category
15.2.1 Index and System of Aeolian Desertification Category
15.2.2 Synthetic Indicator System of Aeolian Desertification Monitoring by Remote Sensing
15.3 Range and Types of Aeolian Desertification in China
15.4 The Spatial Characteristics of Aeolian Desertification in China
15.4.1 Regional Differences
15.4.2 Spatial Distribution
15.5 The Temporal Characteristics of Aeolian Desertification in China
15.5.1 Temporal Distribution
15.5.2 Temporal Change
15.6 Measures to Control Aeolian Desertification
15.6.1 Vegetative Method
15.6.2 Mechanical Method
15.6.3 Chemical Method
15.6.4 Combination of Different Measures
15.7 Rehabilitation Patterns of Aeolian Desertification Lands in China
15.7.1 Rehabilitation Pattern in Semi-Arid Region
15.7.2 Rehabilitation Pattern in Arid Region
15.8 Summary
References
16 The Landslide/Debris Flow and Control Technology in China
16.1 Distribution Law and Characters of Landslide/Debris Flow in China
16.1.1 Mountain Hazards in China
16.1.2 Distribution of Landslides and Debris Flows
16.2 Formation Condition and Mechanism
16.2.1 Formation Condition of Hazards
16.2.2 Formation Mechanism
16.3 Disaster Prevention
16.3.1 Monitoring and Early Warning System on Landslide and Debris Flow
16.3.2 Engineering Countermeasures of Landslide and Debris Flow
References
17 Soil and Water Conservation Policies Change in the Yellow River Basin, China
17.1 Introduction
17.2 The Yellow River Basin (YRB)
17.2.1 General Condition
17.2.2 Soil Erosion and Sediment Load
17.3 Law and Policy on Soil and Water Conservation
17.3.1 Law and Policy on Soil and Water Conservation
17.3.2 The Stages of Policy
17.4 The Policy Evolution in Each Stage Through a DPSIR Framework
17.4.1 DPSIR Framework
17.4.2 Data for Policy Change Analysis
17.4.3 The Change of Policy With DPSIR Framework
17.4.4 Policy Responses in Different Stages
17.5 Achievements and Perspectives of Soil and Water Conservation in YRB
17.5.1 Impacts of Soil and Water Conservation
17.5.2 Perspectives of Soil and Water Conservation in YRB
References
18 Degradation Hazards and Conservation Approaches for Hillslope Farming in Taiwan, China
18.1 Introduction
18.1.1 The Setting and Environment
18.1.2 Soil and Water Conservation Challenges
18.2 Hillslope Utilization Management and Policies
18.2.1 Slopeland Capability Classification Strategy
18.2.2 Appropriate Soil and Water Conservation Practices
18.3 Integrated Watershed Conservation and Restoration
18.4 Rural Villages Rejuvenation
18.4.1 Motivating Local People
18.4.2 Successful Case Studies
18.5 Future Vision
References
19 Soil Conservation Practices and Efforts Made to Combat Desertification in the United Arab Emirates
19.1 Introduction
19.2 Moisture and Temperature Regimes of the Emirate Soils
19.2.1 Aridic and Torric (L. Aridus, Dry, and L. Torridus, Hot and Dry) Soil Moisture Regimes
19.2.2 Hyperthermic is the Soil Temperature Regime
19.3 Importance of Soils
19.4 Soils of the United Arab Emirates
19.4.1 Aquisalids
19.4.2 Calcigypsids
19.4.3 Haplocalcids
19.4.4 Haplocambids
19.4.5 Haplogypsids
19.4.6 Haplosalids
19.4.7 Petrocalcids
19.4.8 Petrogypsids
19.4.9 Torriorthents
19.4.10 Torripsamments
19.5 Indicators of Land Degradation and Desertification
19.6 Evaluation of Soil Movement Mechanisms Through Particle Size Analyses
19.7 The Major Causes of Soil Erosion and Soil Conservation Practices
19.7.1 Coastal Protection Efforts Through Mangrove Establishment
19.7.2 Land Degradation and United Nations Convention to Combat Desertification (UNCCD)
19.7.3 United Arab Emirates Efforts to Comply UNCCD
19.8 Conclusions and Recommendations
Acknowledgements
References
20 Land Degradation in Iran
20.1 An Introduction to General Situation of Iran
20.2 Nature of Main Soil and Water Resources Issues in Iran
20.2.1 Erosion and Sediment-Related Issues
20.2.2 Water Issues
20.2.3 Land Use Change
20.2.4 Overgrazing
20.2.5 Soil Salinity
20.2.6 Forest Fire
20.2.7 Flooding
20.2.8 Wetland Loss
20.3 Magnitude of Main Soil and Water Resources Issues in Iran
20.3.1 Magnitude of Erosion and Sediment-Related Issues
20.3.2 Magnitude of Water Issues
20.3.3 Magnitude of Land Use Change
20.3.4 Magnitude of Overgrazing
20.3.5 Magnitude of Soil Salinity
20.3.6 Magnitude of Forest Fire
20.3.7 Magnitude of Flooding
20.3.8 Magnitude of Wetland Loss
20.4 Hot Spots of Land Degradation in Iran
20.5 Environmental Impacts of Land Degradation in Iran
20.5.1 Environmental Impacts of Erosion and Sediment-Related Issues
20.5.2 Environmental Impacts of Water Issues
20.5.3 Environmental Impacts of Land Use Change
20.5.4 Environmental Impacts of Overgrazing
20.5.5 Environmental Impacts of Soil Salinity
20.5.6 Environmental Impacts of Forest Fire
20.5.7 Environmental Impacts of Flooding
20.5.8 Environmental Impacts of Wetland Loss
20.6 Conservation Efforts to Control Land Degradation in Iran
References
European Region
Introduction of the First Authors
21 Soil Erosion in Europe: From Policy Developments to Models, Indicators and New Research Challenges
21.1 Introduction
21.2 European Policy Context
21.3 Methodology and Model Description
21.4 Results
21.4.1 Spatial and Temporal Analysis of the Soil Erosion 2016 Assessment
21.4.2 Assessment in Agricultural Lands and Soil Erosion Indicator
21.5 Scenario Analysis: The Effect of Land Use Change and Climate Change
21.6 Erosion Integration with Sediment Transport
21.7 Erosion Integration with Soil Organic Carbon
21.8 Global Assessment of Soil Erosion
21.9 Concluding Remarks
References
22 Soil Protection Policies in the European Union
22.1 Introduction
22.2 Background
22.2.1 Environmental Policy Making in Europe
22.2.2 Legislating on Soil Protection in Europe
22.3 EU Policies for Soil Protection
22.3.1 Overarching Policies
22.3.2 Agriculture and Forestry
22.3.3 Industrial (Point Source) Contamination of Land
22.3.4 Diffuse Pollution and Water Management
22.3.5 Nature Protection, Land Use Planning and Soil Sealing
22.3.6 Climate and Energy Policy
22.4 Conclusion
References
23 Soil Conservation Programmes and Policies in England and Wales
23.1 Introduction
23.2 Soil Degradation Issues in England and Wales
23.2.1 Processes Involved
23.2.2 Impacts of Soil Degradation on Soil Functions and the Delivery of Ecosystem Goods and Services
23.3 Programmes and Policies to Manage Soil Degradation in England and Wales
23.3.1 Policy Background
23.3.2 Policy Instruments For Soil Conservation
23.3.3 Codes of Practice Related to Soil Conservation
23.3.4 Certification Schemes Referring to Soil Conservation
23.4 Discussion and Analysis
23.5 Conclusions
References
24 Integrating Soil, Water and Biodiversity Policies: A Case Study from Scotland
24.1 Introduction
24.2 Theoretical Background
24.2.1 The Meaning of Policy, Integration and Environmental Management
24.2.2 Analytical Framework for Policy Integration
24.3 Methods and Materials
24.3.1 Environmental Policy in Scotland
24.3.2 Methodology
24.4 Results
24.4.1 References to Soil, Water and Biodiversity Objectives
24.4.2 Objectives and Types of Policy Instruments for Soil, Water and Biodiversity
24.4.3 Conceptual, Operational and Implementation Integration
24.5 Discussion and Conclusion
Acknowledgements
Appendix A
Appendix B
References
25 Soil Erosion and Flooding in Bulgaria-Risk Assessment and Prevention Measures
25.1 Introduction
25.2 Background
25.2.1 Soil Erosion
25.2.2 Floods
25.3 Material and Methods
25.3.1 Soil Erosion
25.3.2 Floods
25.4 Results and Discussion
25.4.1 Soil Erosion
25.4.2 Floods
25.5 Conclusion
References
26 Natural and Socio-Economic Effects of Erosion and Its Control in Serbia
26.1 Introduction
26.2 Natural Factors of Erosion Processes and Torrential Floods
26.3 Socio-Economic Aspects of Erosion Processes and Torrential Floods
26.3.1 Population Growth in Serbia and Worldwide
26.3.2 Migrations
26.3.3 Migrations in Serbia
26.3.4 Anthropogenic Factors of Torrential Floods and Erosion Processes
26.3.5 Serbian Contribution to the WOCAT: Cooperation Between People and Porečje Company in the Region of the Mt. Kukavica
26.4 Sustainable Management of Land Resources-Prevention of Torrential Floods and Erosion Processes
26.4.1 Participation of the Community in the Natural Resources Management —Community Based Natural Resources Management (CBNRM)
26.4.2 Production Model from the Aspect of Land Resources Protection
26.5 Conclusions
Acknowledgements
References
27 Erosion Control and Torrential Flood Management by Checking Dam Construction in Serbia
27.1 Introduction
27.2 History of the Check Dam and Torrent Mitigation Strategy in Europe
27.3 Construction of Check Dams in Serbia
27.4 The Structural Analysis of the Check Dam Designs
27.5 Effects of Classical Check Dams
27.6 New (Modern) Check Dams
27.6.1 Deposit (Settling Basin) Check Dam by Prof. Rosić
27.6.2 Construction of Check Dams for Bed Load Management
27.7 Recommendation for Check Dam Construction in Serbia
27.8 Conclusion
References
28 Soil Erosion and Torrent Control in Western Balkan Countries
28.1 Introduction and Background
28.2 Aims, Objectives and Methodology
28.3 Factors that Contribute to Erosion and Torrents in the WBC
28.3.1 Relief and Hydrography
28.3.2 Climate
28.3.3 Land Cover/Use
28.4 Erosion and Torrents in the Western Balkan Countries
28.4.1 Erosion in WBC
28.4.2 Torrents and Torrent Floods in the WBC
28.5 Erosion and Torrent Control in the Western Balkan Countries
28.5.1 Erosion and Torrent Control Per Country
28.5.2 Comparison of Erosion and Torrent Control Works Between Countries
28.6 Conclusion
References
29 Identification of Soil Resources Problems in European Russia
29.1 Introduction
29.2 Soil Erosion on the Agricultural Lands the European Russia
29.2.1 History of Agriculture and Water Soil Erosion on European Part of Russia
29.2.2 The Contemporary Sheet and Rill Erosion in the European Russia
29.2.3 Gully Erosion in the European Russia
29.2.4 Transformation of Land Use After the USSR Collapse
29.3 The Desertification Issue in Russia: Main Drivers and Tendencies
29.3.1 Peculiarities of Desertification Assessment in Russian Federation
29.3.2 Desertification Mapping
29.3.3 Causes and Trends in Land Degradation
29.3.4 Social and Economic Consequences of Desertification
29.3.5 Zoning of Desertification
29.4 Soil Pollution
29.4.1 Chemical and Biological Soil Pollution
29.4.2 Radioactive Soil Pollution
29.5 Concluding Remarks
References
30 Soil Erosion on the Agricultural Lands of the Asian Part of Russia (Siberia): Processes, Intensity and Areal Distribution
30.1 Introduction
30.2 Conditions of the Soil Erosion Development in Siberia
30.2.1 Relief
30.2.2 Climate
30.2.3 Soils
30.2.4 Vegetation
30.3 Processes of Slope Wash
30.3.1 Rate of Soils Loss on Slopes with Natural Steppe Vegetation
30.3.2 The Intensity of Soil Loss from by Snowmelt Runoff in Western Siberia
30.3.3 The Intensity of Soil Loss from Arable and Pasture Lands of Eastern Siberia
30.4 Territorial Distribution of Soil Erosion
30.4.1 Erosion Hazard of Rains
30.4.2 Anti-Erosion Stability of Soils
30.4.3 Erosion Potential of the Relief
30.4.4 Soil Protection Properties of Agrocenoses
30.4.5 Erosion-Hazardous Lands in the South of Eastern Siberia
30.5 Trends in Erosion Processes
30.6 Gully Erosion
30.7 Soil Deflation in Siberia
30.8 Erosion Zoning of Siberia
References
31 Ecological Consequences of Soil Degradation and Water Pollution in the Asian Part of Russia (Siberia)
31.1 Ecological State of Soils in the South
31.2 Agrogenic and Post-Agrogenic Transformation of Soils of Tunka Depression (South-Western Baikal Region)
31.3 Ecological Consequences of Water Pollution in the Asian Part of Russia
31.3.1 Sedimentation and Degradation of Small Rivers
31.4 Soil-Protective Research and Activities in the South of Siberia
References
32 Soil Erosion on Agricultural Lands in the Russian Far East Region
32.1 Factors Contributing to Soil Erosion in the Russian Far East
32.2 Erosional Zoning of the Far East
32.3 Distribution and Intensity of Erosion Processes
32.3.1 The Amuro-Zeysky Province
32.3.2 The Amuro-Sakhalin Province
32.3.3 The Near-Pacific Province
32.4 Influence of Soils Loss on Their Fertility
32.5 Ecological Consequences of Soil Degradation and Water Pollution
References
Australian Region
Introduction of the First Authors
33 Issues and Challenges in the Rehabilitation and Sustainable Use of Highly Disturbed Lands Associated with Mining Activities in Australia
33.1 Introduction
33.1.1 Acidic, Neutral and Saline Discharges
33.1.2 Definition of Restoration Towards an End Land Use
33.2 Types and Extent of Land Disturbance
33.3 Case Studies
33.3.1 Restoration of Ecosystem After Bauxite Mining
33.3.2 Designing Postmining Landscapes Following Open-Cut Coalmining that Minimise Erosion Risk and Discharges on the Receiving Environment
33.4 Summary
References
34 Issues and Challenges in the Sustainable Use of Soil and Water Resources in Australian Agricultural Lands
34.1 Introduction
34.2 Soil Acidification
34.2.1 Susceptible Agricultural Sectors and Trends in Soil Acidification
34.2.2 Impacts of Soil Acidification
34.3 Soil Organic Matter Decline
34.3.1 Soil Organic C
34.3.2 Nutrient Depletion
34.3.3 Impacts of Loss of Soil Organic Matter: Soil Structural Decline
34.3.4 Management Options to Restore Soil Organic Matter
34.4 Degradation Associated with Salinity and Sodicity
34.4.1 Definitions of Saline, Sodic and Saline-Sodic Soils
34.4.2 Changing Land Use and Degradation Through Soil Salinization and Sodification
34.4.3 The Extent and Impact of Salinity and Sodicity in Rangeland and Cropping Lands
34.4.4 Management and Rehabilitation of Salinity and Sodicity
34.5 Wind Erosion
34.5.1 Dust Storm Index (DSI)
34.5.2 Factors Leading to Reduced DSI
34.6 Soil Erosion by Water
34.6.1 Australia’s Response to Degradation Associated with Water Erosion
34.6.2 GBR Case Study
34.7 Technical Knowledge Base
34.8 Executive Summary
References

Citation preview

Rui Li · Ted L. Napier · Samir A. El-Swaify · Mohamed Sabir · Eduardo Rienzi Editors-in-Chief

Global Degradation of Soil and Water Resources Regional Assessment and Strategies

Global Degradation of Soil and Water Resources

Rui Li • Ted L. Napier • Samir A. El-Swaify Mohamed Sabir • Eduardo Rienzi

•

Editors-in-Chief

Global Degradation of Soil and Water Resources Regional Assessment and Strategies

123

Editors-in-Chief Rui Li Institute of Soil and Water Conservation CAS/MWR and NWUAF Yangling, Shaanxi, China Samir A. El-Swaify Department of Natural Resources and Environmental Management University of Hawaii Honolulu, HI, USA

Ted L. Napier The Ohio State University Mount Gilead, OH, USA Mohamed Sabir Soil and Water Conservation National School of Forest Engineering Ministry of Agriculture Sale, Morocco

Eduardo Rienzi University of Buenos Aires Lexington, KY, USA

ISBN 978-981-16-7915-5 ISBN 978-981-16-7916-2 https://doi.org/10.1007/978-981-16-7916-2

(eBook)

Jointly published with Science Press The print edition is not for sale in China (Mainland). Customers from China (Mainland) please order the print book from: Science Press. ISBN of the Co-Publisher’s edition: 978-7-03-062787-2 Plan Approval NO.: GS(2019)5116 © Science Press 2022 This work is subject to copyright. All rights are reserved by the Publishers, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publishers, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publishers nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publishers remain neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Preface

Land resources, especially water and soils are the most valuable resources for meeting human needs. The sustainable management of these resources is essential for achieving global food security and meeting other critical needs. Global estimates of total degraded area vary from less than 1 billion ha to over 6 billion ha. An estimated 1.3 to 1.5 billion, or more people worldwide are adversely affected by some aspect of land degradation. Soil degradation, the loss of soil or decline in its quality and functionality, is the most prevailing form of land degradation, and is caused by a variety of natural geologic and anthropogenic processes. In turn, soil erosion is a natural physical process which, when accelerated by misuse or mismanagement, is the most predominant form of soil degradation. In recent years, due to the rapid growth of world population, urban encroachment, increasing development and use of lands with marginal quality, the rapid development of “modern” technologies designed to cope with population needs, soil erosion has accelerated significantly. While opinions differ on the causes of this acceleration, the following factors appear to be instrumental: • • • •

Increased need to develop steeply sloping and other marginal lands for agriculture, Abandoning crop rotations in favor of sole or plantation cropping, Shorted interval of cultivation cycles in tropical areas, Reduced fallow periods in arid or semi-arid areas in favor of intensive continuous cropping, and • Exploitive activities in support of urban development, including land clearing, mining, road construction, infrastructure building, mechanization, and similar activities. Decision makers in some countries have recognized the detrimental impacts of land, soil and water degradation, and proceeded with policies and actions to control their extent and impacts. Some have achieved good results, particularly in reclaiming previously productive land resources. Basic approaches included the adoption of science-based policies, strengthening protective regulations, monitoring the adoption of these regulations, implementing (controversial) subsidy support systems, and employing appropriately trained support (e.g. extension) workers. The purpose of the book is to address the lack of recent state-of-the-art and state-of-the-science documentation of global degradation issues. While we intended to design it primarily for educational purposes at the undergraduate higher education stages, we now hope that it will also address the needs of decision makers at many levels from the user to the policy maker. Book chapters were commissioned to scholars throughout the world who have extensive professional experience in the fields of land and soil degradation and conservation, especially in their own regions. Authors are also well versed in the relevant literature within the regions they are addressing. For discussion purposes, the planet was subdivided into several geographic/administrative regions that are representative of the different types of social, economic and climatic conditions that influence development, including land clearing, mining, road construction, infrastructure building, mechanization, and similar activities. v

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Preface

Decision makers in some countries have recognized the detrimental impacts of land, soil and water degradation, and proceeded with policies and actions to control their extent and impacts. Some have achieved good results, particularly in reclaiming previously productive land resources. Basic approaches included the adoption of science-based policies, strengthening protective regulations, monitoring the adoption of these regulations, implementing (controversial) subsidy support systems, and employing appropriately trained support (e.g. extension) workers. The purpose of the book is to address the lack of recent state-of-the-art and state-of-the-science documentation of global degradation issues. While we intended to design it primarily for educational purposes at the undergraduate higher education stages, we now hope that it will also address the needs of decision makers at many levels from the user to the policy maker. Book chapters were commissioned to scholars throughout the world who have extensive professional experience in the fields of land and soil degradation and conservation, especially in their own regions. Authors are also well versed in the relevant literature within the regions they are addressing. For discussion purposes, the planet was subdivided into several geographic/administrative regions that are representative of the different types of social, economic, and climatic conditions that influence land, soil, and water resource problems. These discussion regions represent the variability in the nature, scope and seriousness of soil and water problems that plague the planet. The chapters in the book are focused on the following three issues of degradation and control for the regions or countries. The first issue includes the spatial-temporal characteristics, driving factors and environmental impacts of soil and water resource problems within the discussion region. The second issue deals with the soil/water conservation actions and measures within the designated region. The third issue is focused on the most significant conservation programs and policies that have been used to address soil and water resources problems within the region. Alternative approaches that could be employed to more effectively reduce degradation of soil and water resources within the geo-political region are suggested. When published, this book may be considered as a beginning volume of a WASWAC Book Series on “Degradation of Land and Water Resources: A Global Issue”. The book plan was initially proposed by Dr. Ted L. Napier and ended up as a true team effort. Drs. Napier and El-Swaify designed the book’s structure, invited the co-editors representing various regions, invited authors representing Europe, North America and the Pacific Region, respectively; and led the technical review process. Professor Rui Li invited authors from Asia and arranged the editing and publishing processes. As the co-Editors Drs. Mohamed Sabir and Eduardo Rienzi invited authors from Africa and South America, respectively; and provided the necessary reviews and editing of their chapters. More than 116 co-authors from Africa, Asia, North America, South America, Europe, Pacific Region, and Australia submitted 34 chapters for the book. Mr. Tan Zhang arranged the editorial reviews of all chapters. The Secretariat for the World Association of Soil and Water Conservation (WASWAC) and Institute of Soil and Water Conservation (Northwest A&F University & CAS/WRM) provided the necessary financial support and assisted in organizing the editing and printing processes. While the word “Global” is embedded in this book’s title, the editors realize that we may be lacking some countries or regions from around the globe. We expect this to represent an opening for future follow-up contributions to come. Yangling, China Mount Gilead, USA Honolulu, USA Sale, Morocco Lexington, USA

Rui Li Ted L. Napier Samir A. El-Swaify Mohamed Sabir Eduardo Rienzi

Contents

Part I

Introduction—Overview of Global Soil and Water Stress

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Probabilistic Land Use Allocation in the Global Soil Erosion Modelling . . . . Pasquale Borrelli, Panos Panagos, Cristiano Ballabio, and Christine Alewell

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Soil Erosion and Its Impacts on Greenhouse Gases . . . . . . . . . . . . . . . . . . . . Rattan Lal

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Assessing Multiple, Concurrent and Interactive Land and Soil Degradation Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Samir A. El-Swaify

Part II

African Region

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Agricultural Soil and Water Conservation Issues in East Africa . . . . . . . . . . Narindra H. Rakotovao, Tantely M. Razafimbelo, Herintsitohaina R. Razakamanarivo, Jennifer H. Hewson, Nandrianina Ramifehiarivo, Andry Andriamananjara, Yacine B. Ndour, Saidou Sall, Mohamed Sabir, Hervé Aholoukpe, Lucien G. Amadji, Oumarou Balarabe, Edmond Hien, Jean Paul B. Olina, Armand Koné, Adoum Abgassi, Alain Albrecht, Michel Brossard, and Martial Bernoux

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Institutional and Technical Efforts for the Soil and Water Conservation in North Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mohamed Sabir, Abdellah Laouina, Boutkhil Morsli, and Mohamed Annabi

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Sustainable Use of Soil and Water Resources to Combat Degradation . . . . . . Samiha Ouda, Hamdy Khalifa, Abdalla Mohamadin, and Abd El-Hafeez Zohry

Part III 7

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19

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American Region

Long-Term Effects of Different Agricultural Soil Use and Management Systems on Soil Degradation in Uruguay . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fernando García-Préchac, Lucía Salvo, Oswaldo Ernst, Guillermo Siri-Prieto, J. Andrés Quincke, and José A. Terra Assessment of the Utility of the Diffusion Model for Facilitating Adoption of Soil and Water Conservation Production Systems in North America . . . . . Mark Tucker, Ted L. Napier, and Newton M. Nyairo

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Eight Decades of USDA Soil and Water Conservation Policies and Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Corey Cockerill, Ted L. Napier, Rebecca Minardi, and Dillon Davidson vii

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Contents

10 Market Approaches for Addressing Soil and Water Resources Problems . . . 119 Marc O. Ribaudo 11 Desertification in Argentina: The Causes and Effects on Human Beings . . . . 131 Stella Maris Navone Part IV

Asian Region

12 Characterization of Soil and Water Resources in Yemen . . . . . . . . . . . . . . . . 151 Mohammed Hezam Al-Mashreki 13 Soil Erosion Environment Background and Its Spatial Distribution in China . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Fenli Zheng, Qinke Yang, Chao Qin, Jiaqiong Zhang, and Rui Li 14 Water Erosion and Its Control in China . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Yun Xie and Zhijia Gu 15 Aeolian Desertification Status and Its Control in China . . . . . . . . . . . . . . . . . 199 Tao Wang, Guangting Chen, Halin Zhao, and Honglang Xiao 16 The Landslide/Debris Flow and Control Technology in China . . . . . . . . . . . . 221 Peng Cui 17 Soil and Water Conservation Policies Change in the Yellow River Basin, China . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Fei Wang, Duihu Ning, and Rui Li 18 Degradation Hazards and Conservation Approaches for Hillslope Farming in Taiwan, China . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 Kwong-Fai Andrew Lo 19 Soil Conservation Practices and Efforts Made to Combat Desertification in the United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 Shabbir Ahmad Shahid and Tareefa S. Alsumaiti 20 Land Degradation in Iran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 Seyed Hamidreza Sadeghi and Zeinab Hazbavi Part V

European Region

21 Soil Erosion in Europe: From Policy Developments to Models, Indicators and New Research Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Panos Panagos, Emanuele Lugato, Cristiano Ballabio, Irene Biavetti, Luca Montanarella, and Pasquale Borrelli 22 Soil Protection Policies in the European Union . . . . . . . . . . . . . . . . . . . . . . . 335 Ana Frelih-Larsen and Catherine Bowyer 23 Soil Conservation Programmes and Policies in England and Wales . . . . . . . . 351 Jane Rickson and Michael Fullen 24 Integrating Soil, Water and Biodiversity Policies: A Case Study from Scotland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367 Katrin Prager, Kirsty Blackstock, Jessica Maxwell, Alba Juarez-Bourke, and Kerry Waylen 25 Soil Erosion and Flooding in Bulgaria-Risk Assessment and Prevention Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 Svetla S. Rousseva and Ivan Ts. Marinov

Contents

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26 Natural and Socio-Economic Effects of Erosion and Its Control in Serbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 Miodrag Zlatić, Mirjana Todosijević, Katarina Lazarević, and Natalija Momirović 27 Erosion Control and Torrential Flood Management by Checking Dam Construction in Serbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415 Nada Dragović, Stanimir Kostadinov, and Tijana Vulević 28 Soil Erosion and Torrent Control in Western Balkan Countries . . . . . . . . . . 425 Ivan Blinkov, Stanimir Kostadinov, Ivan Mincev, and Ana Petrovic 29 Identification of Soil Resources Problems in European Russia . . . . . . . . . . . . 449 Valentin N. Golosov, Tatiana Paramonova, German Kust, Leonid Litvin, and Olga Andreeva 30 Soil Erosion on the Agricultural Lands of the Asian Part of Russia (Siberia): Processes, Intensity and Areal Distribution . . . . . . . . . . . . . . . . . . . 475 Olga I. Bazhenova, Elizaveta M. Tyumentseva, and Viktor A. Golubtsov 31 Ecological Consequences of Soil Degradation and Water Pollution in the Asian Part of Russia (Siberia) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499 Olga I. Bazhenova, Anna A. Cherkashina, Elizaveta M. Tyumentseva, Viktor A. Golubtsov, and Larisa M. Sorokovikova 32 Soil Erosion on Agricultural Lands in the Russian Far East Region . . . . . . . 517 Aleksei N. Makhinov and Aleksandra F. Makhinova Part VI

Australian Region

33 Issues and Challenges in the Rehabilitation and Sustainable Use of Highly Disturbed Lands Associated with Mining Activities in Australia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525 Hwat Bing So, Thomas Baumgartl, Richard W. Bell, and Ashraf M. Khalifa 34 Issues and Challenges in the Sustainable Use of Soil and Water Resources in Australian Agricultural Lands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537 Chris Carroll, Calvin W. Rose, Richard Greene, Brian Murphy, Ram Dalal, Kwong Y. Chan, and Hwat B. So

About the Editors-in-Chief

Rui Li is a Professor at the Institute of Soil and Water Conservation (ISWC), Chinese Academy of Sciences and Ministry of Water Resources, and ISWC of Northwest A&F University. Address: Xinong Road 26, Yangling, Shaanxi Province, China. Email address: [email protected]. He is the current president of the World Association of Soil and Water Conservation (WASWAC). He specializes in land resources evaluation, land use planning, monitoring soil and water degradation via remote sensing and GIS technologies. His principal research focuses on soil erosion and conservation at regional and global scales. He has coordinated and participated in more than 30 research projects relating to soil and water conservation. He has published over 120 articles in professional journals and published 12 books as principal editor or co-editor. He has received a number of awards because of his contributions to soil and water conservation research and management. Ted L. Napier is an Emeritus Professor of Environmental Studies at The Ohio State University, Columbus, Ohio. Home address: 7326 St. Rte. 19, unit 2902, Mt. Gilead, OH 43338. E-mail address: [email protected]. Telephone number: 614-284-2277. Dr. Napier has been a faculty member of The Ohio State University for 49 years. He has published articles extensively in domestic and international journals and is the author or co-author of several books focusing on the adoption of soil and water conservation production systems at the farm level. His research has been cited many times by peers in the field. Research Gate has identified approximately 1000 citations of the incomplete list of his publications listed with their organization. Ted has presented papers, consulted professionals/agencies, and conducted research in over 55 countries. He has been recognized numerous times by various professional groups for his contributions to the field of soil and water conservation. Samir A. El-Swaify Emeritus Professor and Founding Chair, Department of Natural Resources and Environmental Management, University of Hawaii, Honolulu Hawaii. Email address: [email protected]. Telephone: 808-956-7530. Professor El-Swaify holds a B.S. in Agricultural Science from the University of Alexandria, Egypt and a Ph.D. in Soil Science from the University of California at Davis. He has been a faculty member at the University of Hawaii for over 51 years. During his career, Professor El Swaify has produced over 150 publications focusing on soil science and broader natural resource conservation issues. He has been recognized by several professional organizations for his many contributions to the field of soil and water conservation especially in tropical environments. He has contributed to the formation and functioning of many soil and water conservation groups in multiple regions of the planet. Mohamed Sabir is a professor of Soil and Water Conservation in the National School of Forest Engineering, Ministry of Agriculture. Mailing address: ENFI, BP 511,11 015, Tabriquet, Sale, Morocco. Email address: [email protected]. Professor Sabir holds a Ph. D. in Soil and Water Conservation. His research has been focused on watershed management and agroforestry. He has published articles extensively on the impacts of grazing on arid lands

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and the impact of land use on soils and erosion. He has examined the role of land husbandry on Mediterranean mountains of Morocco. Professor Sabir has contributed to several regional and global professional organizations focusing on soil and water conservation issues. Eduardo Rienzi Professor of Management and Conservation, University of Buenos Aires. Home address while in the USA: 1101 Beaumont Center, apartment number 15303, Lexington Kentucky 40513. Email address: [email protected]. Eduardo Rienzi has been a faculty member of the University of Buenos Aires for 26 years. He is a soil scientist with extensive training in agronomic engineering. He is a former extension educator working as an agronomy agent among farmers located in Cordoba province in Argentina. He has published 52 papers in journals and in proceeding of professional meetings. Dr. Rienzi developed extensive skills in GIS modelling during a postdoctoral appointment within the Precision Agriculture Laboratory at the University of Kentucky. He is presently offering two graduate level courses in spatial analyses at the University of Buenos Aires.

About the Editors-in-Chief

Part I Introduction—Overview of Global Soil and Water Stress

Introduction of the First Authors Pasquale Borrelli is a Research Associate at the Research Center Ecosystem Services of Surface Soil Enviroment, Kangwon National University, Chuncheon- si, Gangwon-do, Republic of Korea. Email: [email protected]. During the last 12 years, Dr. Borrelli has gained professional research skills in outstanding universities, European institutions (i.e. JRC) or United Nations’ FAO. Today, he is recognized as a leading international scientist in the areas of GIS erosion modelling and soil conservation planning. The GSP Secretariat recently selected him as the project leader of FAO’s soil erosion modelling project which integrates science and policy to promote a land degradation neutral world by 2030 (UN SDGs). So far, Dr. Borrelli has published over 60 international peer-reviewed publications (source Google Scholar) with 3300+ citations. Rattan Lal is a professor of soil science and director of the Carbon Management and Sequestration Center at the Ohio State University. Email address: lal.1@osu. edu. Dr. Lal was the President of the World Association of Soil and Water Conservation (WASWAC) and is presently the President of the International Union of Soil Sciences(IUSS). His research

has been focusing on climate-resilient agriculture, soil carbon sequestration, sustainable intensification, enhancing use efficiency of agroecosystems, and sustainable management of soil resources. He has received numerous professional awards for his contributions to his fields of study. Dr. Lal has authored/co-authored more than 2000 research publications including 818 refereed journal articles and 485 chapters. He has written 19 books and 65 edited/ co-edited books. Samir A. El-Swaify, Emeritus Professor and Founding Chair, Department of Natural Resources and Environmental Management, University of Hawaii, Honolulu Hawaii. Email address: [email protected]. Telephone: 1+808-277-2598. Professor El- Swaify holds a B.S. in Agricultural Science from the University of Alexandria, Egypt and a Ph.D. in Soil Science from the University of California at Davis. He has been a faculty member at the University of Hawaii for over 51 years. During his career he has produced over 150 publications focusing on soil science and broader natural resource conservation issues. He has been recognized by several professional organizations for his many contributions to the field of soil and water conservation especially in tropical environments. He has contributed to the formation and functioning of many soil and water conservation groups in multiple regions of the planet.

1

Probabilistic Land Use Allocation in the Global Soil Erosion Modelling Pasquale Borrelli, Panos Panagos, Cristiano Ballabio, and Christine Alewell

Abstract

We present the version 1.2 of the recently published [Nature communications 8, 2013 (2017)] RUSLE-based Global Soil Erosion Modelling platform (GloSEM). Unlike version 1.1, effects of permanent crops, managed pasture and temporary disturbed forest loss are spatially defined based on a probabilistic land by using allocation approach and their implications for soil erosion are assessed in the advanced version 1.2. For 2012, we estimated an annual total soil erosion of 38.9 Pg/a. This constitutes an increase of ca. 8% compared to the previous version (35.9 Pg/a) which is due to an increase of soil erosion mainly related to the new areas classified as managed pasture and to a lesser extent to permanent crop and forest disturbances. Human activity and related land use change are the primary cause of accelerated soil erosion by water, which has substantial implications for nutrient and carbon cycling, land productivity and thus worldwide socio-economic conditions (Borrelli et al. 2017a). Feeding the Earth’s growing population with increasing dietary preferences towards livestock products has the potential to exacerbate the erosion phenomena thereby enhancing the pressure on world’s soil resources. Impacts of soil erosion can be severe, not only through land degradation and fertility loss, but also through a conspicuous number of off-site effects (e.g., sedimentation, siltation and eutrophication of waterways or enhanced

P. Borrelli (&) Kangwon National University, Gangwon-do, Chuncheon-si, Republic of Korea P. Panagos  C. Ballabio Joint Research Centre, European Commission, Ispra, Italy C. Alewell Environmental Geosciences, University of Basel, C4056 Basel, Switzerland

flooding) and impacts on biogeochemical cycling (Quinton et al. 2010). Quantitative global assessment on the state and change of soil erosion is needed to identify soil erosion hotspots and provides a meaningful starting point to support decision-makers in both ex-ante and ex- post policy evaluation. Scientifically, such estimates are important to deepen our understanding on the significance of soil-erosioninduced impacts. Global soil erosion dynamics have been described based on scientific soil expert judgments (Oldeman 1992; FAO and ITPS 2015) through the extrapolation of plot and river sediment data (Lal 2003) and RUSLEbased modelling (Ito 2007). The resulting estimates are equivocal in that they vary from about 20 Pg/a and more than 200 Pg/a although expert judgments advise that estimates of global soil erosion exceeding 50 Pg/a may not be realistic (FAO and ITPS 2015). Following the publication of pioneering studies such as the Global Assessment of Soil Degradation (GLASOD) (Oldeman 1992), subsequent research aimed to improve the ability to predict soil erosion at global scale using spatially explicit modelling approaches. USLE and RUSLE became by far the most applied soil erosion prediction models. Among others, Van Oost et al. (2007), Ito (2007) and Doetterl et al. (2012) have presented (R)USLE-based global soil erosion applications. While these approaches range in their degree of complexity, their coarse resolution modelling (ca. 10-60 km cell size) with a static observation approach limits, their predictive power to assess the effects of frequent land use changes and to identify soil erosion hotspots. Moreover, high erosion values as predicted by Yang et al. (2003) (ca. 132 Pg/a) and Ito (2007) (ca. 172 Pg/a) are far above the threshold of 50 Pg/a indicated in the latest reference document of the United Nations (UN) on the status of global soil resources (FAO and ITPS 2015). In a later study, Borrelli et al. (2017a) investigated global soil erosion dynamics by means of high- resolution spatially distributed modelling (ca. 250
250 m cell size). The

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_1

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P. Borrelli et al.

proposed geo-statistical approach aims at overcoming the limitations of previous models allowing for the first time, the thorough incorporation of land uses and their changes, the extent, types, spatial distribution of global croplands, and the effects of the different regional cropping systems into a global soil erosion model. Combined with an improved global assessment of the global rainfall erosivity dynamics, the latest globally consistent dataset paved the path towards a state-of-the-art global RUSLE-based model. The results of Borrelli et al. (2017a) shed light on the impacts of the twenty-first century global land use change on soil erosion and provide insights into potential mitigating effects due to the conservation agriculture. They are limited, however, with regard to the inability to define some forms of land use that are important for soil erosion modelling such as loss of permanent crops, managed permanent pasture and temporary forests (due to fires and wood harvesting). Furthermore, perennial crops and managed pasture were represented only implicitly within the semi-natural grass vegetation class. Here, we present an advanced version 1.2 of Borrelli’s global model (GloSEM) where perennial crops, managed pasture and temporary forest loss are spatially delineated through a probabilistic land use allocation scheme to outline the global arable land as in Borrelli et al. (2017a). The share of land covered by permanent crop and managed pasture is defined according to the national statistics provided by FAOSTAT (http://www.fao.org/faostat/en). The spatial distribution across the country follows a downscaling scheme that uses the Land-Use Harmonization (LUH2) product (Hurtt et al. in preparation) as spatial guide. Land that can potentially be allocated to perennial crops and managed pasture is the agricultural land spatially defined in the MODIS Land Cover Type product MCD12Q1 as IGBP-12 class (croplands) and IGBP-14 class (croplands/natural vegetation mosaic) (please note that these areas are classified as semi-natural vegetation in the previous version 1.1).

Table 1.1 C factor values assigned to the perennial crops managed pasture and disturbed forest sectors

Land use Perennial crops Managed pasture Disturbed forest

The reallocation was done based on classification rules applied to the auxiliary information provided in the MODIS MCD12Q1 product (i.e., classification confidence and second most likely IGBP class at each cell) and global forest tree cover based on Landsat imagery Hansen’s global forest tree cover based on Landsat imagery (Hansen et al. 2013). In case of managed pasture, the pixels were preferentially reclassified according to the following rules: IGBP-12 rather than IGBP-14, higher classification confidence, and from the lowest (0) to the highest wooden cover. With regard to perennial crops, applied rules are IGBP- 14 rather than IGBP-12 thus resulting in a higher classification confidence to select from the highest (set to 49%, non-forest land) to the lowest wooden cover. This simplification of the complexity and heterogeneity of the global agricultural areas allowed us to perform a targeted selection of the areas potentially exploited as perennial crops and managed pasture. With regard to temporary forest loss, Hansen’s global annual forest cover for 2001 and 2012 (Hansen et al. 2013) was combined with annual gross forest cover loss events (lossyear) to spatially identify the temporary forest loss. Map algebra was used to resample data at ca. 250 m cell size. For the definition of the C-factor values (Table 1.1), we followed the path paved in previous national (Borrelli et al. 2016a; 2017b) and pan- European (Panagos et al. 2015; Borrelli et al. 2016b) studies but we assumed a strong increase of the C-factor directly after forest disturbance with a gradual recovery over 10 years (Table 1.1). The modelling approach provides a prediction of the soil loss by water erosion for each of the ca. 2.9 billion cells covering *84.3% of the Earth’s land surface (ca. 250
250 m cell-size). The total surface is slightly larger than the one presented in Borrelli et al. (2017a) due to the integration of the Greenland’s ice-free lands. The predicted long-term average soil loss rate is ca. 3 Mg/(haa) [Fig. 1.1, compared to 2.8 Mg/ (haa) in model version 1.1. Borrelli et al. (2017a)]. The

Status

C-factor

Description

Min

0.01

Vegetation cover close to 100%

Max

0.385

Vegetation cover close to zero

Min

0.05

Vegetation cover close to 100%

Max

0.15

Vegetation cover close to zero

Pre-disturbance

0.0001–0.009

From dense to sparse cover

1 year post-disturbance

0.175

Vegetation recovery phases

2 years post-disturbance

0.12

3 years post-disturbance

0.075

4 years post-disturbance

0.009

5–10 years post-disturbance

0.009–0.003

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Probabilistic Land Use Allocation in the Global Soil Erosion Modelling

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Fig. 1.1 Global rates of soil displacement by water erosion estimated through the RUSLE-based GloSEM V1.2. The estimates are predicted through a RUSLE-based modelling approach integrated in a geographic information system (GIS) environment. The colour gradation from green to red indicates the intensity of the predicted erosion rates

baseline run of the model (without soil conservation practices) predicts an annual average potential soil erosion amount of 38.9 Pg/a for 2012. Arable land covers about 11.2% in 2012 and is responsible for 46% of the total predicted soil erosion. Its average value [12.7 Mg/(haa)] is more than four times higher than the overall soil erosion rate. It is estimated to be 77 times higher than in forests [0.16 Mg/(haa)] and around seven times higher than the average of the other natural vegetation [1.67 Mg/(haa)]. Compared to version 1.1, the other natural vegetation incurred a decrease in average soil erosion of about 9% [1.84 Mg/(haa)]. The change is attributable to the reorganization of this land use class that experienced a substantial reduction due to the reallocation to perennial crops and managed pasture land uses. These show predicted soil erosion rates of 5.35 Mg/(haa) and 6.68 Mg/(haa), respectively. The

Fig. 1.2 Soil loss estimates predicted through RUSLE-based GloSEM V1.2 for agricultural lands, i.e., arable land, managed pasture and disturbed forest

total soil loss is equal to 0.77 Pg/a for the perennial crops and 4.73 Pg/a for the managed pasture. With regard to annual crops (arable land), the total annual þ1 average soil erosion was estimated at 170:7 Pg/a, with an with the confidence intervals referring to the variation between the conservation and baseline scenarios (superscript) and the conservation scenario assuming the maximum technical efficiency of the employed conservation practices (subscript). The sum of the soil loss predicted for the global arable land, the permanent crops and the managed pasture indicate a potential total soil displacement in the agricultural land of 23.4 Pg/a [10.4 Mg/(haa)] for the year 2012 (Fig. 1.2). The uncertainty of the spatial predictions was estimated using a Markov Chain Monte Carlo (MCMC) approach (Borrelli et al. 2017a). The sum of the uncertainty

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related to a reduction due to the conservation agriculture jointly with the error associated with the input data results in þ 4:9 predictions for agricultural land of 23:42:5 Pg/a, with an þ 2:2 area-specific soil erosion average of 10:41:1 Mg/(haa). The predicted annual gross soil loss average in the lands that experienced a temporary forest loss (i.e., no land use conversion) is estimated as 0.19 Pg/a, with an average area-specific soil loss of 6 Mg/(haa). The average annual soil loss in forests that remained undisturbed during the modelling period is equal to 0.16 Mg/(haa). The areas of forest cover change mapped by Hansen et al. (2013) (Figs. 1.3 and 1.4), here assumed to be due to tree harvesting or wildfires, show a predicted average area-specific soil loss more than thirty times higher than the one estimated for undisturbed forests. Notably, 26% of the soil loss is predicted to occur in the disturbed forest areas although these areas cover only a small part of the forest and ( semiarid areas > semi-humid area > humid areas. However, spatial differences of the correlation between C value and wind speed as well as precipitation are large (Dong and Kang 1994). Combining the variations of wind erosion climatic factor and soil erodibility, wind erosion in China are mainly distributed in the arid and semi-arid area of the northern China, which has two distinguishing zonal and temporary periodicity features (Gong 2014). Due to the regional differences of

climate, geomorphology, soil type, vegetation type and the land use in arid and semiarid area, wind erosion pattern, process and magnitude show more complex zonal distribution characteristics. Taking northern part of the Loess Plateau as an example, this area can be divided into three different regions. One region is named temperate desert grassland locating at northern area of the Loess Plateau, characterized by warm temperate steppe, strong wind erosion zone, the annual wind erosion intensity is 5000–10,000 t/(km2 a); another region is named central warm temperate steppe, characterized by moderate wind and water erosion crisscross zone, and the annual wind erosion intensity is 2000–5000 t/ (km2 a). The last region is the southern warm temperate steppe, characterized by mild wind and water erosion crisscross zone, the annual wind erosion intensity is < 2000 t/ (km2 a). Even through the wind erosion is relatively light in the southern warm temperate steppe region, this area is located at the transition zone of loess and desert which belongs to wind and water erosion crisscross zone, the surface material has high susceptibility for wind erosion, and results in severe erosion (wind and water erosion), and becomes the most severe erosion region of the whole Loess Plateau. There are periodic trends of wind erosion intensity in arid and semi-arid areas in China on different time scales. Besides variation of wind erosion intensity with seasons,

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wind erosion intensity has 3, 7, 14, 23, 50 and 145 years’ periodic variation during a long period in northern Loess Plateau and the Ordos Region (Gan 1989).

13.1.3 Soil Environment and Soil Erosion in China Soil is the object by erosion agent. Soil erosion intensity is dependent soil physical and chemical properties, such as soil organic matter content, soil texture and structure, as well as soil permeability etc. Due to climate changes, variations of geological and topographic conditions, especially long history of cultivation and intensive human being activities, diverse soil types and characteristics home formed in China. Moreover, soil spatial distribution can be divided into humid soil regions in the southeast of China, dry soil area in central China and arid soil area in Northwest China. Soil erodibility (K factor) reflects the sensitivity to soil erosion, and it is a comprehensive index of soil sensitivity to rainfall and runoff erosion. Liang et al. (2013) collected soil records from 30 provinces (regions and cities) in China, and estimated the K values in the whole country and provinces (regions) by using the soil organic matter, soil structure and soil texture from typical soil profiles (Fig. 13.2). The results showed that the K values of the main soils in China were between 0.0004 and 0.0828 t ha h/(ha MJ mm). And the minimum K value appeared in Shaanxi, and the maximum K value occurred in Beijing. According to the average K value of each province (regions), the minimum K value appeared in Guangdong Province, this is because the soil in Guangdong Province has the higher content of soil clay and organic matter. On the contrary, the content of clay and organic matter was lower in Qinghai Province, consequently the average K value was the highest among 30 provinces (regions). Studies on soil erodibility in China have made a great progress. Zhang et al. (2001) pointed out that the seasonal variation of soil erodibility varied significantly in different soil types, climatic characteristics, and farming management and they also estimated the soil erodibility in China. Wang et al. (2013) assessed the applicability of main soil erodibility estimate models, such as USLE (Wischmeier and Smith 1965), RUSLE (Renard et al. 1997), EPIC (Sharply and Williams 1990), and Dg (Römkens et al. 1988) models, in the main four water erosion regions of China. The results showed that the USLE model and the Dg model have good estimation of K values in the black soil region of Northeast China and the Loess Plateau area, respectively. On the contrary, estimating equations of K in the USLE, RUSLE2 and EPIC models overestimated the soil erodibility in China. Wang et al. (2013) also established an equation for estimating soil erodibility in major water erosion areas

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(Northeast black soil region, the Loess Plateau, the south red soil region, and Sichuang purple soil region) in China, in which only two factors (SOM, soil organic matter and Dg, soil texture) were contained. In addition, Wang’s equation has a higher precision for estimating K value in main water erosion regions in China.

13.1.4 Vegetation and Soil Erosion in China Vegetation is an important affecting factor of soil erosion. Forest ecosystem with better vertical structure can intercept rainfall, reduce overland flow velocity, disperse surface runoff, trap sediment, consolidate soil and ameliorate soil, which can control soil erosion occurrence and prevent erosion development. However, once vegetation is destroyed, soil erosion occurs at once and develops. The change of vegetation types and its coverage rate can cause different soil erosion types and soil erosion intensities. Complex geological tectonic movement, especially the uplift of the Qinghai-Tibetan Plateau basically determined climate characteristics in China, which induce the basic patterns of vegetation in China (Jing et al. 2005). The distribution of vegetation in China is not only affected by latitude zonation (heat) and longitude zonation (water), but also affected by vertical variation of altitude, which produce three- directional zonalities of vegetation distribution in China (China Vegetation Editorial Board 1980). In terms of horizontal zonality, the precipitation gradually decreases from southeast to northwest in China due to the summer monsoon; consequently, the vegetation types in China show obviously longitude changes, and successions of vegetation types from southeast to northwest are deciduous broad-leaved forest/coniferous broadleaved mixed forest, meadow steppe, typical steppe, desert steppe, steppe desert and typical desert (China Vegetation Editorial Board 1980). On the other hand, latitude zonation of vegetation types in China is also obvious with the latitude decline from north to south and successions of vegetation types are as follows: coniferous forest in the cold temperate zone, the coniferous broad-leaved mixed forest in the cold temperate zone, the coniferous broad-leaved mixed forest in the temperate zone, the deciduous broad-leaved forest in the warm temperate zone and the evergreen broad-leaved forest in the subtropics, the tropical monsoon rain forest/rainforest (China Vegetation Editorial Board 1980). Moreover, the vertical zonation of vegetation types along mountain altitude can be divided into two types: humid region and arid area (China Vegetation Editorial Board 1980). In the eastern monsoon region with the abundant of rainfall, the vegetation types along mountain altitude is dominated by the forest vegetation type, which has relatively complete vertical zonation. The variations of vegetation types increased with elevation are as follows:

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Fig. 13.2 Regional soil erodibility (USLE-K factor) map [t ha h/(ha MJ mm)] (Wang et al. 2016)

coniferous broadleaved mixed forest, cold and warm coniferous forest, subalpine dwarf forest, and alpine tundra. However, in the northwest inland arid region, the dry grassland or desert vegetation often occupies the dominant position. The variations of vegetation types with increased elevation are as follows: desert steppe/typical steppe,

temperate coniferous forest (shady slope), subalpine thicket meadow, alpine meadow, mountain tundra. According to the China vegetation atlas (1∶1 million) (Chinese Academy of Sciences China Vegetation Map Editorial Board 2001), the coverage area of all vegetation types in China occupies 75.4% of total land area. But, forest

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coverage in China is only about 22%, which is below the global average of 31%. Taking large amount of population in China into account, the forest resources are even more insufficient. The forest area per capita is only a quarter of the world average, and the forest stand volume per capita is only one seventh of the world average. Generally speaking, soil erosion is in close relation with vegetation cover. Soil erosion greatly decreased with the increase of vegetation coverage; and the decreasing percentage of soil erosion by vegetation cover was related to vegetation types, soil properties and topography. During the past decades, due to a large number of cultivation, soil erosion became very serious. Destruction of forest, overgrazing and mining have caused soil erosion to be more severe in the warm-temperature zone and temperature zone. Currently, quantitative indicator of vegetation cover is NDVI (normalized difference vegetation index), which is extracted from remote sensing image. NDVI can be used to monitor dynamic changes of vegetation coverage. Liu (2015) estimated the vegetation coverage of China in 1982, 1990, 2000 and 2010 based on the NDVI respectively, and classified grades of vegetation cover: excellent vegetation is the vegetation coverage greater than 0.8, good vegetation is the vegetation coverage between 0.6 and 0.8, the moderate vegetation is the vegetation coverage between 0.4 and 0.6, the poor vegetation is the vegetation coverage between 0.2 and 0.4, inferior vegetation is the vegetation coverage less than 0.2. According to the average vegetation coverage of the four tested periods, the excellent vegetation cover area only accounts for 8.4% of the national land area, the good vegetation coverage area occupies 20.4%, the moderate vegetation coverage area accounts for 20.2%, the poor vegetation coverage area accounts for about 14.8%, and the inferior vegetation accounts for about 36.2%. From 1982 to 2010, the vegetation coverage of the whole country showed a gradual increase trend, in which the area of excellent vegetation coverage increased from 6.8 to 11.3%, and the area of inferior vegetation coverage decreased from 36.8 to 35.7%. Generally, vegetation coverage in China decreases from southeast to northwest. Most of the excellent vegetation is distributed in the coastal areas of southeast China, such as Zhejiang, Fujian, Hainan provinces; the good vegetation is mainly distributed in southern and parts of northeast China, such as Guizhou, Chongqing, Yunnan, Hubei and Heilongjiang; the moderate vegetation is mainly distributed in some central provinces, such as Sichuan, Henan, Jilin and other provinces; the poor vegetation is mainly distributed in the north-central region, such as eastern Tibet, southern Qinghai and eastern Inner Mongolia; the inferior vegetation is mainly distributed in the northwest region, including Xinjiang, Tibet, Qinghai, Gansu and western Inner Mongolia.

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13.1.5 Impacts of Human Activities on Soil Erosion in China During the long agricultural history in China, the impact of human activities on soil erosion has obvious duality. On the one hand, unreasonable utilization of land, especially the destruction of natural vegetation, aggravated soil erosion. On the other hand, soil erosion was effectively controlled through a series of soil and water conservation measures and ecological restoration and protection projects. 1. Unreasonable land exploitation and utilization aggravating soil erosion According to the records, China used to be a country with dense forests in history, the forest coverage rate was as high as 60% for the whole country (Zhang 2012), and 80–90% in some regions of northeast and southwest China (Li 2001). As a result of natural climate change, population growth, deforestation for land reclamation burning of forests and hunting, as well as frequent civil wars, soil erosion was aggravated. The intensification of soil erosion was closely related to population growth and human activities. Throughout Chinese long history, it can be summarized into the following four stages of soil erosion acceleration (Ministry of Water Resources et al. 2011; Liu 2018). (1) Stage I: From pre-Qin to Western Han In the pre-Qin period (before the 3rd century BC), the national population was only 20 million, and in Zhou dynasty people paid more attention to the protection of mountain lands, forests and rivers, the forest coverage rate was about 53%, and the Yellow River water was clearer. However, from the Qin dynasty to the Western Han dynasty, the population quadrupled and reached 59.59 million in the first two years of the Ping emperor of Western Han dynasty. In order to meet food need, the state encouraged station troops to open up land, and many nomadic areas on the Loess Plateau were cultivated as agricultural areas. Forests and grasslands were destroyed. Soil erosion became more and more serious and the Yellow River water became yellow, and in the lower reaches of the river gradually became suspended river. As the result, the lower stream of the Yellow River was frequently flooded and diverted in this period (Ministry of Water Resources et al. 2011; Liu 2018; Jing et al. 2005). (2) Stage II: From Eastern Han to Sui, Tang, Song and Yuan dynasties From Eastern Han dynasty to Sui dynasty, the civil war continued and the population decreased greatly. Until the

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beginning of Taikang of Eatern Jin dynasty (AD 280) population was only 16.16 million. In 755 AD, 14th of Tianbao in Tang-Xuanzong period, the population increased to 53 million. Although there was the War of Five Generations, the population was never less than 30 million. Until the 27th year of the Yuan dynasty (AD 1300), the population was 58.84 million. The forest area deceased greatly, consequently, soil erosion was more severe. Only in the period of Song dynasty, the Yellow River crevasse was cut more than 40 times (Ministry of Water Resources et al. 2011; Liu 2018; Jing et al. 2005).

environment protection and violated natural roles, new soil erosion from non-agriculture industries was more severe in some regions. According to the survey, from 2000 to 2005, the total area of soil erosion caused by various construction projects in China reached 2.737 million ha, and the amount of soil and slag abandoned reached 9.21 billion tons (Liu 2018).

(3) Stage III: From Ming/Qing dynasties to the middle of the twentieth century

China is an ancient agricultural country. During the long period farming practices, farmers have accumulated rich experiences in soil erosion control. There are several books to describe soil and water conservation theories and practices in ancient China, such as Records of the Grand Historian (Shi Ji), Classic of History (Shang Shu), and Book of Songs (Shi Jing). Throughout the history of China, in the ancient age, there were many doctrines on bio-resources protection, ecological balance and reasonable land-use, such as “Soil and Water Conservation” and “Gully- care for river safety”. From “North-Song” to “Ming- Qing”, some famous and practicable theories of soil and water conservation were created and formed, such as “Catchment care and land management”, “River- source priority”, “Sediment control from sources” and “Forest for fixing sand and controlling runoff” and so on. Chinese farmers have developed and accumulated a series of soil and water conservation measures, such as soil conservation tillage, slope-land terracing, planting grass and tree, check dam and others. Mr. Li Yizhi had a very detail discussion on the measures of soil and water conservation in his Book “The fundamental principles for Yellow River management”. Since the 1950s, for nearly 70 years, great achievements have been made in soil and water conservation in China. By 2011, the area of various soil and water conservation measures in China has reached 99.16 million km2, and the number of engineering, plant and other measures is 20,300, 778,500 and 12,800 km2, respectively (Ministry of Water Resources et al. 2011; Liu 2015; Liu 2018). Generally speaking, during the past nearly 70 years, soil and water conservation can be divided into three distinct phases in China (Liu et al. 2015). ① The first phase is from 1950s to 1980s. In this phase, the priorities were to reduce river sedimentation and ensure the river safety, and to meet to basic need of people’s living in the eroded regions. Many river bone engineering projects and basic farmland construction, such as terraced fields, dam lands etc., were the main tasks of soil and water conservation. ② The second phase is from 1980s to the beginning of this century. In this phase with the Chinese economy and industry development,

In the Qing dynasty, the policy of encouraging population growth was put in practice. In the second year of Yongzheng (1724), the population of China was 25 million. Until the 31st year of Qianlong (1766) the population was tripled and increased to 209 million in 42 years. Until the 29th year of Daoguang (1849), after 83 years, the population doubled again to 470 million. Over the 600 years since the Ming and Qing dynasties, forests were destructively destroyed. Soil erosion was unprecedentedly serious, and the ecological environment deteriorated sharply. For example, in Ming dynasty, nearly 300 years, the Yellow River overflowed more than 60 times. At the beginning of the Qing dynasty in 1644, the national forest coverage rate was 21%, but until 1949, it was only 8.6%. In many parts of the country, the landscape was bare, and the ecological environment was seriously deteriorated (Ministry of Water Resources et al, 2011; Liu 2018; Jing et al, 2005). (4) Stage IV: Up to the middle of the twentieth century Up to the middle of the twentieth century, with the end of the civil war, China came to a well developing period. At the same time the population entered a period of rapid growth. Grain production has become the first cardinal issue. Due to the low level of productivity, the land suffered heavy pressure from both population growth and the extensive traditional cultivation. Many lands suitable only for forest and pasture were exploited for farmland and cultivation. Deforestation and destroying vegetation cover, even digging up roots and sod caused soil erosion to aggravate seriously. According to relevant data, the national total cultivated sloping lands with more than 25° were up to more than 6 million ha, most of which were from deforestation or destroyed grass land (Tang 2004; Liu 2018). Since the 1980s, with rapid development of China’s economy and society, a large number of construction, industry and mining projects have been implemented. Due to neglected

2. Rich experiences for preventing and controlling soil erosion have been obtained through the long- period agricultural practices

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soil and water conservation entered a new period. Besides paying more attention to local economic development and grain production, and improving the land productivity, it is obviously characteristic to take small watershed as a unit for the comprehensive allocation of measures of soil and water conservation. ③ The third is since the beginning of this century. With the rapid growth of Chinese economy and society, besides more and more investments to soil and water conservation, more new and scientific concepts and policies were proposed and were also put into practices. It has become the common understandings to achieve the harmony between human and nature, to win both economic and ecological benefits, and the mountains with green vegetation and clear water are considered to be “Gold/Silver” mountains. The Chinese Government proposed GGP (Grain for Green Project, meaning conversion of sloping farm lands to permanent vegetation cover) and other related polices, such as the natural forest protection project and the large scale afforestation project, in soil erosion areas. The GGP has achieved great progresses and benefits, such as in many regions, degraded ecology system has got restoration, slope cropland has been covered by trees and grass, bare mountain and hills have been changed with green vegetation cover. As a result the soil erosion has been controlled and reduced obviously in China. According to the above-mentioned, environmental background of soil erosion in China has five characteristics: ① There one three natural environmental units with different features, i.e. eastern region with dominant moist and sub-moist, northwestern region with dominant arid and sub-arid, Qinghai-Tibet Plateau with dominant high-cold, ② three steps topography structures from west to east (Editorial Board of Chinese Natural Geography and Chinese Academy of Sciences 1985; Tang 2004), ③ low vegetation cover and uneven spatial distribution, ④ active modern geology tectonics movement, ⑤ long-term unreasonable landuse and intense contradiction between people and land. These environmental backgrounds of soil erosion and its features determine soil erosion types, soil erosion intensity, and their spatial distribution.

13.2

Spatial Distribution of Soil Erosion in China

According to the principle of soil erosion exogenic agent (water, wind, freeze and thaw et al.) dominating in a relative large region, soil erosion types in China are divided as three main regions (primary region): eastern soil erosion region by water (I), northwestern soil erosion region by wind (II), and Qinghai-Tibet Plateau soil erosion region by freeze- thaw (III) (Xin and Jiang 1982; Jing et al. 2005; Wang et al. 2016; Soil and Water Conservation Planning Work Leading Group

Office and the Water Resources and Hydropower Planning and Design Institute of the Ministry of Water Resource 2017). For the soil erosion region by water, which covers a large area with complex topography and different climate, five sub-regions (secondary region) were further divided based on topography. These five sub-regions include: northeast soil erosion sub-region of lower mountains and gentle slope hills, northwest soil erosion sub-region of Loess Plateau, northern soil erosion sub-region of earth and stone mountains, southern soil erosion sub- region of mountains and hills and southwestern soil erosion sub-region of mountains and hills (Fig. 13.3) (Wang et al. 2016). The characteristics of three main regions of soil erosion types are described in the following paragraphs.

13.2.1 Eastern Soil Erosion Region by Water (I)

1. Northeast soil erosion sub-region of lower mountains and gentle slope hills (I-1) This soil erosion sub-region is surrounded by Da Hinggan Mountains, Xiao Hinggan Mountains and Changbai Mountains at west, north and east boundary. The south boundary locates at the south of Jilin Province. This region covers Heilongjiang Province, Jilin Province, most of Liaoning Province, and a small part of Inner Mongolia Autonomous Region. In addition to Sanjiang Plain, the rest of places have soil erosion at different degrees. As one of the four large black soil (Mollisol) areas in the world, soil erosion intensity shows increasing trend because of unreasonable farming activities. Black soil layer thickness in some cultivated lands has decreased from 50 to 80 cm in 1950s to currently 20–40 cm. The significant soil erosion characteristic is the compound erosion induced by multi exogenic agent combination, namely the freeze-thaw erosion in winter and early spring, late spring snow melt, wind erosion, and tillage erosion. Rainfall mostly concentrates in the summer with high intensity, maximum daily precipitation is 120–160 mm, sometimes even up to 200 mm, the maximum rainfall intensity is 1.6 mm/ min. Black soil contains high organic matters; the topsoil will be loose after tillage, especially after drought and freezing, lasting several months in winter every year. Hence, windy and drought spring often causes severe wind erosion, a strong wind can blow away 1–2 cm of topsoil. Meanwhile, gully erosion is also severe in this area. According to the National Survey, there are 295,663 gullies, including 262,178 active gullies and gully density is 0.21 km/km2 (Ministry of Water Resources and Chinese Academy of Science, Chinese Academy of Engineering, 2011).

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Fig. 13.3 Soil Erosion types in China (Wang et al. 2016)

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Erosion rate per year in the sloping farmlands is 0.3–6 mm (Feng et al. 2017; Yang et al. 2016). The Loess Plateau is the most typical developed loess region with widest distribution area, thickest loess layer, and one of the severest soil erosion areas in the world. This sub-region covers the west of the Taihang Mountains, the east of Riyue Mountain, the north of Qinling Mountains, and the south of the Great Wall. This sub-region covers Qinghai, Gansu, Shanxi, Shaanxi, Henan, Ningxia and Inner Mongolia. This region belongs to continental monsoon climate, annual average rainfall is lower than 700 mm, gradually decreasing from southeast to northwest. Rainfall concentrates in July, August, and September, which accounts for about 50–70% of annual precipitation. Precipitation interannually greatly changes, the maximum annual precipitation is 849.6 mm, while the minimum annual precipitation is 199.6 mm, the differences reached to even more than four times. In summer and fall, rainstorms with large rainfall amount and intensity are important reasons of serious soil erosion on the Loess Plateau. This region is dry and windy, and the monthly average wind speed is 1.1–2.9 m/s, average wind speed for April to August is more than 3 m/s. The strong wind mainly appears in the spring, which results in obvious desertification. Average soil erosion intensity is 2130 t/(km2 a), and the area with soil erosion intensity greater than 50,000 t/(km2 a) is about 1,560,000 km2. 3. Northern soil erosion sub-region of earth and rock mountains (I-3) This soil erosion sub-region refers to the mountainous and hilly regions of northern and central southern China, covering the south of northeast lower mountain and gentle slope hills, east of the Loess Plateau, north of the Huaihe River. The distinctive features of this sub-region are thin soil layer and high gravel content, and serious soil coarse ossification is caused by soil erosion. Precipitation in this sub-region increased from south to north spatially, average annual participation is 500–600 m in the north and 700–1000 mm in the south, more than 80% of rainfall concentrated in the summer with high intensity. Due to human activities and vegetation destruction, areas with an altitude below 800 m all become barren hills, which are the most serious soil erosion areas of the Taihang Mountains. High mountain areas with altitude was higher than 800 m, have thicker soil layer and more natural secondary forest with less human activities, but there are still steep slope farming and overgrazing activities to some extent.

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Due to thin soil layers with poor permeability bedrock and concentrated rainstorms in summer, landslide and debris flows frequently occurs in this sub-region. 4. Southern soil erosion sub-region of mountains and hills (I-4) This sub-region set Dabie Mountain as north boundary, Ba Mountain and Wu Mountain as west boundary, Yunnan-Guizhou Plateau as southwest boundary, the southeast end reaches to sea areas, including Taiwan, Hainan, and the islands of the South China Sea. Most parts of this sub-region belong to the subtropical climate zone, only a small part of the region is tropical climate zone, annual precipitation is 1000–2000 mm, the maximum daily precipitation is over 150 mm, the highest precipitation in 1 h is more than 30 mm. Annual runoff depth is more than 500 mm, the maximum is 1800 mm, and the runoff coefficient is 40–70%. The temperature in this sub-region is high, weathering process of surface materials is quick; therefore, granite purple sandshale, and red soil are easy to be eroded. The main soil erosion characteristics of this region is serious water erosion, gully erosion and collapsed hills erosion induced by summer rainstorm. Gravel layer contains huge stone blocks and provides the geological basis for the gravitational erosion. The areas with where vegetation destructed by human activities have high potential risks of soil erosion. After middle of 1980s, soil erosion in farmlands decreased, but the mining and infrastructure induced new soil erosion issues. 5. Southwestern soil erosion sub-region of mountains and hills (I-5) This sub-region locates in the southwest of China. Its south border is sub-region I-4, west border is region III (freeze– thaw region to the west), north border is sub-region I-2, with a total area of 753,000 km2. This sub-region is dominated by high mountains and deep valleys, the erosive agents are complex which are dominated by water erosion and gravitational erosion; especially, gravitational erosion in this region is the most serious place in whole country. This sub-region belongs to monsoon climate zone, it is not only influenced by southwest monsoon, but also affected by the east Asian monsoon and the west wind circulation as well as the Qinghai-Tibet Plateau edge airflow. Rainfall is abundant in this region, annual precipitation is 1000–1200 mm, annual average rainfall precipitation mainly concentrates in the middle of May to early November, and 70–80%

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of total precipitation concentrates in May–September, runoff coefficient is 40–50%. Serious water erosion is the main characteristic in this region, compound erosion types such as landside and debris flow are also serious.

13.2.2 Northwestern Soil Erosion Region by Wind (II) China’s wind erosion mainly distributed in the western of northeast China, north China, northwest China, for a total area of 1.876 million km2, accounting for about 19.0% of the whole country. Among them, the desert area accounts for 637,000 km2, sand gravel and Gobi area accounts for 458,000 km2. This region, located in the centre of continent, is affected by continental monsoon climate. Precipitation in this region is low, annual rainfall in most parts is lower than 300 mm, thus the surface vegetation coverage rate is very low. Soil matrix in this region is sand soil, under the risk of wind erosion all the time. In some areas, due to the excessive development of oasis, the underground water level drops and some lakes are dried up. Overgrazing and unreasonable land use induce desertification. The wind erosion and land desertification have become the major natural disasters in northwest China, which are the most intractable ecological issues.

13.2.3 Qinghai-Tibet Plateau Soil Erosion Region by Freeze–thaw (III) This sub-region is mainly distributed in mountain areas of the Qinghai-Tibet Plateau, the high mountain area in western and northern China, and northernmost freeze-thaw zones at high altitudes. Except for freeze- thaw erosion, water erosion and wind erosion are also distributed here. Freeze-thaw erosion can be divided into two categories: glacier erosion and frozen soil erosion. Due to climate changes and human activities, distribution of freeze-thaw erosion area showed a decrease trend in China. The First National Soil Erosion Survey shows that freeze-thaw erosion area is 1.25 million km2 (Wang et al. 2015; Soil and Water Conservation Planning Work Leading Group Office and the Water Resources and Hydropower Planning and Design Institute of the Ministry of Water Resource 2017). Permanent freeze-thaw erosion area and seasonal freeze-thaw erosion area are mainly distributed in south of the Karakorum and Kunlun mountains, north of the Yarlung Zangbo River and the south Tibet valleys. South part of the Yarlung Zangbo River with an altitude of 4200–4780 m strip is also seasonal freeze-thaw erosion area. With the growth of the population and social economy development, expansion

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of human activities induced larger scale use of natural resources, leading to increasingly serious new soil erosion in this region. Under the effect of freezing and thawing circles, turf and top soil can be saturated to produce the mud flow, which then slowly creeps along the slope. Except for freeze-thaw erosion, water erosion and wind erosion also distribute in this area. Water erosion is mainly concentrated in the sources of the Yangtze, Yellow, and Lancang rivers and the middle reaches of the Yarlung Zangbo River valley of eastern Tibet, which belongs to humid and semi-humid regions. Due to the high and steep mountains, fragile surface rock, high gravel content in soil layers, once surface vegetation is disturbed or destructed, it is easy to cause large area erosion and even disasters including landslides, debris flow. Wind erosion region is mainly concentrated in Ali area, central western Nagqu area and the Yarlung Zangbo river valley area, soils are loose in these regions, coupled with the lack of rain and the scarce of ground vegetation, serious wind erosion frequently occurs.

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186 Jing K, Wang W, Zheng F (2005) Soil Erosion and Environment in China. Science China Press, Beijing Li B (2001) Environment protection in ancient China. Henan Press, Zhengzhou Li X, Wang G, Li R (2007) The relationship of poverty and water and soil loss. Res Soil Water Conserv 14(1):132–134 Li Z, He Y, Wang P et al (2012) Changes of daily climate extremes in southwestern China during 1961–2008. Glob Planet Change 80:255–272 Liang Y, Liu X, Cao L et al (2013) K value calculation of soil erodibility of China: water erosion areas and its Macromacro-distribution. Soil Water Conserv China 10:35–40 Liu BY, Zhang KL, Xie Y (2002) an empirical soil loss equation. process of soil erosion and its environment effects. In: The proceedings of 12th ISCO conference. Vol II: process of soil erosion and its environment effect. Tsinghua University Press, Beijing, pp 21–25 Liu Z (2018) Soil and water conservation outline. Science China Press, Beijing Liu Z (2015) Summary the experience and seize the change to apply new soil and water conservation law. Soil Water Conserv China 6:1–6 Ma G, Shi M, Li M (2009) Economical cost evaluation of ecological environment degradation in China. China Popul Resour Environ 19 (1):162–168 Ministry of Water Resources of the People’s Republic of China (2013) Discussion on national soil and water conservation survey and application of results. Soil Water Conserv China 10:4–7, 11 Ministry of Water Resources, Chinese Academy of Science, Chinese Academy of Engineering (2011) Comprehensive scientific investigation of soil erosion and ecological security in China. Science China Press, Beijing Renard KG, Foster GR, Weesies GA et al (1997) Predicting soil erosion by water, a guild to conservation planning with the revised universal soil loss equation (RUSLE). USDA Agricultural Handbook No.703. Washington DC: U.S. Government Printing Office Römkens MJM, Poesen JWA, Wang JY (1988) Relationship between the USLE soil erodibility factor and soil properties. In: Rimwanichland S (ed) Conservation for future generations. Department of Land Development, Bangkok Sharply AN, Williams JR (1990) EPIC-erosion/productivity impact calculator I, model documentation. U.S. Department of Agriculture Technical Bulletin, No. 1768. USDA Agricultural Research Service, Washington DC Sheng C (1986) Summary of climate in China. Science China, Beijing Soil and Water Conservation Planning Work Leading Group Office, the Water Resources and Hydropower Planning and Design Institute of the Ministry of Water Resource (2017) Chinese soil and water conservation regionalization. China Water Power Press, Beijing Tang H, Yang XX, Wang X et al (2007) Analyses of precipitation change in the source regions of three rivers during 1956–2004. Plateau Meteorol 26(1):47–54

F. Zheng et al. Tang K (2004) Chinese soil and water conservation. Science China, Beijing Wang B, Zheng F, Mathias JM, Römkens MJM (2013) Comparison of soil erodibility factors in USLE, RUSLE2, EPIC and Dg models based on a Chinese soil erodibility database. Acta Agric Scandinavica Sect B-Soil Plant Sci 63(1):69–79 Wang B, Zheng F, Guan Y (2016) Improved USLE-K factor prediction: a case study on water erosion areas in China. Int Soil Water Conserv Res 4(3):168–176 Wang Y, Yang M, Liu P (2010) The wavelet analysis on the soil erosion intensity in the black soil straight cultivated slope. J Nucl Agric Sci 24(1):98–103 Wang Z, Zhang C, Sun B et al (2005) Overview of national soil and water conservation. Soil Water Conserv China 12:12–17 Wischmeier WH, Smith DD (1965) Predicting rainfall erosion losses from cropland east of the Rocky Mountains. USDA agriculture handbook 282. US Department of Agriculture, Washington DC Xin S, Jiang D (1982) Overview of Chinese soil and water conservation. Agriculture Press, Beijing Yang Q, Zhao M, Liu Y et al (2009) Application of DEMs in regional soil erosion modeling. Geomat World 1:25–31 Yuan W, Zheng J (2015) Spatial and temporal variations of extreme temperature events in southwestern China during 1962–2012. Resour Environ Yangtze Basin 24(7):1246–1254 Yang W, Zheng F, Wang Z et al (2016) Effects of topography on spatial distribution of soil erosion deposition on hillslope in the typical black soil region. Acta Pedol Sin 53(3):572–581 Zhai P, Pan X (2003) Change in extreme temperature and precipitation over Northern northern China during the second half of the 20th century. Acta Geogr Sin 58(s1):1–10 Zhang K, Cai Y, Liu B et al (2001) Fluctuation of Soil Erodibility due to rainfall intensity. Acta Geogr Sin 56(6):673–681 Zhang K, Peng W, Yang H (2007) Soil erodibility and its estimation for agricultureal soil in China. Acta Pedol Sin 44(1):7–13 Zhang L (2012) A review on the history of forest transition in ancient China. Agric Archaeol 3:208–218 Zhang W, Xie Y, Zhang K (2003) Spatial distribution of rainfall erosivity in China. J Mt Sci 21(1):33–40 Zhang X (2001) Gully erosion produces sand and sediment transport. Features and trends of erosion environment in the middle reaches of the Yellow River. Yellow River Water Conservancy Press, Zhengzhou, pp 109–137 Zhang Z (1990) Chinese physical geography diagram. Shaanxi Normal University Press, Xian, p 324 Zheng D, Yang Q, Liu Y (1985) Chinses loess plateau. Science China Press, Beijing Zheng F, Gao X (2010) Soil erosion process and simulation of loess slope. Shaanxi People Press, Xi’an Zhong K, Zheng F, Wu H et al (2017) Effect of extreme precipitation change on sediment transport in Songhua river basin. Trans Chin Soc Agric Mach 48(8):245–252+321 Zhou P, Wang Z (1992) Study on soil erosion and rainstorm in loess plateau. J Soil Water Conserv 6(3):1–5

Water Erosion and Its Control in China

14

Yun Xie and Zhijia Gu

A long history of cultivation and diverse topographic and climatic factors have resulted in severe water erosion in various regions of China; the efforts made by Chinese people to combat this soil erosion also have a long history (Liu 1953; Tang 2004; Liu et al. 2013; Fu et al. 2016; Wang et al. 2017). The Loess Plateau, the region with the most severe water erosion in the world, dubbed “China’s Sorrow” by Lowdermilk (1953), has turned green (Zhang et al. 2011; Liu et al. 2013; Gao et al. 2017), and annual sediment yields from the Plateau to the Yellow River have decreased from (16–2)
108 tons. How did this happen? This chapter will introduce changes in water erosion and its control in China since the 1990s.

14.1

Changes in Water Erosion

Four large-scale soil erosion surveys have been conducted in China since 1949 (Guo and Li 2009). The first took place during the 1950s in the Loess Plateau, and focused on the control of severe soil erosion and sediment yield to the Yellow River. Subsequently, three national soil erosion surveys were carried out in 1989, 1999 and 2010, respectively. However, only the findings of the last two surveys were made publicly available. The analysis of changes in water erosion in this section is based on the results of the latter surveys.

14.1.1 Soil Erosion Surveys in China The first soil erosion survey was conducted in the 1950s in the Loess Plateau, which exhibited some of the most severe soil erosion worldwide. The Chinese Academy of Sciences arranged for Chinese and former Soviet scientists to Y. Xie (&)  Z. Gu Faculty of Geographical Science, Beijing Normal University, Beijing, China e-mail: [email protected]

investigate the factors influencing soil erosion and assess soil erosion intensity by visiting fields, collecting statistical data, and interviewing farmers. After about 3 years’ work, a map of soil erosion intensity in the middle reaches of the Yellow River Basin was authorized (Huang 1995), and has since been used to plan soil conservation in the region. Based on the survey results, the middle portion of the basin was divided into two erosion zones from the southeast to the northwest, based on soil texture, and five erosion sub-regions with different soil erosion intensities were identified within the two zones, based on topography. Three of these sub-regions were located in the southeast zone from northeast to southwest, comprising sub-region 1, with the highest soil erosion modulus (exceeding 10,000 t/km2) in the northeast, and sub-regions 2 and 3 in the middle and southwest, respectively, each with a soil erosion modulus of 5000–10,000 t/km2. Two sub-regions were located in the northwest zone, running from southwest to northeast, comprising sub-region 4, with the smallest soil erosion modulus (1000–2000 t/km2) in the southwest, and sub-region 5 in the northeast, with a soil erosion modulus of 5000–10,000 t/km2. In 1989 and 1999, remote sensing data and digital elevation models (DEMs) were used to identify soil erosion intensity on a national scale. The remote sensing data yielded information on the uses of forestland, grassland, and farmland and the vegetation cover of forest and grassland. Slope degree was estimated for forestland, grassland, and farmland using DEMs. The factor score method was used to measure soil erosion intensity. The remote sensing data for 1989 were drawn from U.S. Terrestrial Resource Satellite– Multi Spectrum Scanner images at a spatial resolution of 79 m
79 m, and those for 1999 were drawn from Thematic Mapper images from 1995 to 1996 with a spatial resolution of 30 m
30 m. In the 1989 survey, the soil erosion area was 3.67 million km2, of which the water erosion area represented 1.79 million km2 and the wind erosion area 1.88 million km2. In the 1999 survey, the soil erosion area was 3.56 million km2, of which the water erosion area

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_14

187

188

represented 1.65 million km2 and the wind erosion area 1.91 million km2. In addition, the water-wind erosion interlaced region was identified, and its area was 260,000 km2. During the fourth national soil erosion survey, in 2010, the Chinese Soil Loss Equation (CSLE) (Liu et al. 2007; Chinese Water Conservancy 2010) was used to assess soil loss by integrating data gathered on site with remote sensing data. Diverging from the previous three surveys, a soil erosion model was used to quantify soil erosion and investigate soil conservation practices. The CSLE differs slightly from the Universal Soil Loss Equation in that C factors (coverage and management) and P factors (conservation practice) are replaced by B factors (conservation biological practice), E factors (conservation engineering practice), and T factors (conservation tillage), according to China’s traditional system of soil conservation classification. To obtain data for the model, a stratified non-equal probability areal sampling method was used to select about 34,000 sample units at a 1% sampling density across the whole country. The sample unit used for field visits was a 0.2–3 km2 small watershed area in which data on land use, conservation measures, the canopy cover of forest and grassland, and crop types were gathered. A survey map of the spatial distribution of land use and conservation measures and an information table were derived for each watershed area. Data on daily rainfall, soil loss from unit plots, the locations of soil types, and soil physical and chemical properties were collected to calculate rainfall erosivity (Wischmeier and Smith 1978; Xie et al. 2002) and soil erodibility (Olson and Wischmeier 1963; Wischmeier and Smith 1965; Zhang et al. 2007). Soil loss for each sample unit was calculated, soil erosion intensity was classified according to soil loss group, and the area of soil erosion was weighted and summed at county, province, and country level. The survey results were published in 2012 (Ministry of Water Resources of the People’s Republic of China and National Bureau of Statistics of the People’s Republic of China 2013). The soil erosion area was 2.95 million km2, of which the water erosion area represented 1.29 million km2 and the wind erosion area represented 1.66 million km2.

Y. Xie and Z. Gu

surveyed. Based on degree of soil loss, erosion intensity was divided into five groups: light erosion, moderate erosion, severe erosion, most severe erosion, and extremely severe erosion. Soil loss in these groups was measured at 200–1000 t/km2, 1000–2000 t/km2, 2000–4000 t/km2, 4000–8000 t/km2, and greater than 8000 t/km2, respectively. Light soil erosion covered 667,600 km2, moderate erosion 351,400 km2, severe erosion 168,700 km2, most severe erosion 76,300 km2, and extremely severe erosion 29,200 km2, accounting for 51.6%, 27.2%, 13.0%, 5.9% and 2.3% of the total soil erosion area (Fig. 14.1), respectively. Light erosion covered the largest area, followed by moderate erosion, together representing 78.8% of the total erosion area, and the three degrees of severe erosion accounted for 21.2% of the total erosion area. 2. Regional variation in soil erosion From an economic perspective, China can be divided into three main regions: eastern China, middle China, and western China. Eastern China comprises nine provinces/municipalities: Beijing, Tianjin, Shanghai, Jiangsu, Zhejiang, Fujian, Shandong, Guangdong, and Hainan. Central China comprises 10 provinces: Hebei, Shanxi, Liaoning, Jilin, Heilongjiang, Anhui, Jiangxi, Henan, Hubei, and Hunan. Western China comprises 12 provinces: Inner Mongolia, Guangxi, Sichuan, Guizhou, Yunnan, Tibet, Chongqing, Shaanxi, Gansu, Qinghai, Ningxia, and Xinjiang (Figure 14.2). The water erosion area in the east was measured at 79,400 km2; that in central China was 397,500 km2; and that in western China was 816,400 km2. The western region had the largest area of water erosion, followed by central China and eastern China. However, the erosion intensity ratio was similar across the three regions: about half was light erosion, a quarter moderate erosion, and the remainder severe erosion (Table 14.1). At province level (Table 14.2), the first 11 provinces with water erosion areas larger than 50,000 km2 were Sichuan,

14.1.2 Current Status of Water Erosion In the 2010 national soil erosion survey, soil erosion intensity, area, and spatial distribution were measured on a national scale, and current soil erosion was compared between provinces. 1. Soil erosion area and intensity The total area of water erosion was 1.29 million km2, accounting for 7.42% of the total area of the territory

Fig. 14.1 Percentage of each water soil erosion intensity in China

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189

Fig. 14.2 Eastern, central and western China

Table 14.1 Water erosion area and percentages of intensity classes in three regions in China

Division

Total area (km2)

Percentage of total area (%) Light

Moderate

Severe

Most severe

Extremely severe

Eastern China

7.94

53.5

26.7

12.9

2.2

1.6

Central China

39.75

49.5

28.9

14.2

2.5

1.8

Western China

81.63

52.5

26.4

12.5

3.5

2.6

129.32

51.6

27.2

13.0

5.9

2.3

Total

Yunnan, Inner Mongolia, Xinjiang, Gansu, Heilongjiang, Shaanxi, Shanxi, Tibet, Guizhou, and Guangxi, as all had a large land area and were vulnerable to erosion (Fig. 14.3a). The water erosion area in these 11 provinces accounted for 67.4% of the total national erosion area. The top three provinces were Sichuan, Yunnan, and Inner Mongolia,

accounting for 25.2% of total national erosion. The 10 provinces/municipalities with the smallest water erosion areas accounted for only 6.2% of total national erosion (Fig. 14.3a). The percentage of water erosion area to land area is a better index of erosion vulnerability. The provinces with

190 Table 14.2 Water erosion area and percentages of intensity classes for each province/municipality

Y. Xie and Z. Gu Province/City/autonomous region

Percentage of national total (%)

Percentage of total area (%) Light

Moderate

Severe

3,202

0.2

54.5

32.2

10.7

2.2

0.4

236

0.0

45.8

25.4

25.0

2.5

1.3

42,135

3.3

53.2

31.1

10.8

3.5

1.5

Total area (km2)

Beijing Tianjin Hebei Shanxi

Most severe

Extremely severe

70,283

5.4

38.0

34.4

20.0

6.1

1.5

102,398

7.9

66.9

19.8

9.9

2.9

0.6

Liaoning

43,988

3.4

50.0

27.3

14.7

6.3

1.8

Jilin

34,744

2.7

49.8

26.0

12.5

8.0

3.7

Heilongjiang

73,251

5.7

49.4

25.0

15.9

7.5

2.2

4

0.0

50.0

50.0

0.0

0.0

0.0

Inner Mongolia

Shanghai Jiangsu

3,177

0.2

65.1

18.7

11.6

4.2

0.5

Zhejiang

9,907

0.8

69.9

20.8

5.9

1.8

1.6

Anhui

13,899

1.1

49.8

30.3

14.1

4.8

1.1

Fujian

12,181

0.9

54.6

26.4

13.3

3.5

2.2

Jiangxi

26,497

2.0

56.2

28.5

11.9

2.9

0.4

Shandong

27,253

2.1

54.8

24.3

13.0

6.3

1.6

Henan

23,464

1.8

43.4

31.7

17.2

6.2

1.6

Hubei

36,903

2.9

56.2

27.8

9.9

4.3

1.9

Hunan

32,288

2.5

60.8

26.9

7.8

3.2

1.4

Guangdong

21,305

1.6

41.7

32.5

16.6

7.7

1.6

Guangxi

50,537

3.9

44.8

28.5

14.6

9.5

2.6

Hainan

2,116

0.2

55.3

31.5

9.0

2.1

2.1

Chongqing Sichuan

31,363

2.4

33.9

30.4

16.5

13.9

5.3

114,420

8.8

42.4

31.3

13.6

8.5

4.2

Guizhou

55,269

4.3

50.1

29.6

10.9

5.4

4.1

Yunnan

109,588

8.5

41.0

31.7

14.5

8.2

4.7

Tibet

61,602

4.8

46.5

38.4

9.6

3.4

2.1

Shaanxi

70,807

5.5

68.1

3.0

20.7

6.5

1.7

Gansu

76,112

5.9

39.8

33.5

16.9

7.1

2.8

Qinghai

42,805

3.3

62.1

23.4

9.0

5.1

0.5

Ningxia

13,891

1.1

49.1

30.8

14.9

3.8

1.5

Xinjiang

87,621

6.8

74.1

21.4

2.9

1.5

0.1

1,293,246

100

51.6

27.2

13.0

5.9

2.3

Total

percentages larger than 25% were Shanxi, Chongqing, Shaanxi, Guizhou, Liaoning, Yunnan, and Ningxia, most of which are distributed across the Loess Plateau and southwest China. The provinces with water erosion area to land area percentages less than the national average (13.7%) were Guangdong, Anhui, Fujian, Zhejiang, Inner Mongolia, Hainan, Qinghai, Xinjiang, Tibet, Jiangsu, Tianjin, and Shanghai, most of which are distributed across eastern China, the northwest arid area, and the Tibetan Plateau (Fig. 14.3b).

Most of China’s soil erosion areas run from the northeast to the southwest of central China, in the topographic transect zone from the alluvial plains to the plateaus (Fig. 14.4). The most severe soil erosion was found to occur in the Loess Plateau, followed by the hilly regions around the Sichuan Basin and Yungui Plateau. The rolling hilly regions to the west of Xiao Hinggan Mountains and the Changbai Mountains in northeastern China, where a black soil region and grain production area are located, also showed serious soil erosion. Based on the percentage of water erosion area to

14

Water Erosion and Its Control in China

191

Fig. 14.3 Area (a) and percentage (b) of water erosion for each province

land area for each province, four regions were identified. The first region was the Loess Plateau, which showed the most serious water erosion. Shanxi Province, where water erosion area accounted for 44% of the total land area, ranked first in China, and Shaanxi Province, with a ratio of 31.4%, ranked third. In many counties in this region, the water erosion area represented more than 30% of the total area. For example, the percentage of water erosion area to land area in Yulin and Yan’an in northern Shaanxi exceeded 40%; that in Qingyang, Tianshui, and Pingliang in Gansu Province was 37.1%; and that in Xiji, Haiyuan, Yuanzhou, Pengyang, and Tongxin in Ningxia was 36.4%. The second of the four collective regions comprised the karst region of southwestern China and the rolling hill region of northeastern China, all of which showed fairly serious erosion. The percentages of water erosion area to total land area in the provinces of Chongqing, Yunnan, Guizhou, Guangxi, and Sichuan in southwestern China were 35.3%, 27.6%, 26.4%, and 25.1%, respectively. The equivalent percentages in Liaoning and Jilin provinces in northeastern China were 30.1% and 24%. At county level, water erosion percentage reached 27.2% of the total land area of Harbin, Suihua, Qiqihar, and Heihe in Heilongjiang Province. The third region, showing moderate soil erosion, was found in central China, comprising the earth-rocky mountain region of northern China and the Middle-Lower Yangtze Basin in the red soil region of southern China. In the provinces of Hebei, Shandong, Henan, Hubei, Hunan, and Jiangxi, the percentage of water erosion area to total land area ranged from 13.5% to 20%. The fourth region, showing light erosion, comprised the Jiangnan hilly area, the Tibetan Plateau, and the northwestern arid area, including the provinces of Guangdong, Anhui, Zhejiang, Fujian, Hainan, Qinghai, Tibet, Xinjiang,

and Jiangsu. The percentage of water erosion area to land area in this region ranged from 1.6% to 11.8%.

14.1.3 Changes in Water Erosion Since the 1990s Comparison with the results of the soil erosion survey in 1999 indicates that the water erosion area decreased from 1.64 million km2 to 1.29 million km2 over 16 years, falling by 347,800 km2 or 21.2%, with an average annual reduction of 21,700 km2. The area of land showed light or moderate erosion decreased obviously, and the area of land with severe water erosion also decreased (Fig. 14.5). This reduction in soil erosion resulted mainly from the conversion of steep slope farmland to forestland or grassland, and the development of conservation practices such as terrace construction. The four provinces showing the most significant reductions in water erosion area were Inner Mongolia, Shaanxi, Gansu, and Sichuan (Fig. 14.6) in the Loess Plateau, collectively exhibiting a reduction of 174,300 km, or 50.1% of the total decrease in China’s water erosion area. Apart from Hubei Province, the 10 provinces showing the greatest reductions in water erosion area were all in western China, with a collective decrease of 320,200 km2, accounting for 92.1% of China’s total reduction. Comparison with the 1999 erosion survey results reveals that the percentage of reduced water erosion area to total water erosion area decreased significantly in 27 provinces (Fig. 14.7). Reduction percentages exceeding 30% were observed in Tianjin, Zhejiang, Shaanxi, Chongqing, Hubei, Gansu, Ningxia, and Inner Mongolia. However, water

192

Y. Xie and Z. Gu

Fig. 14.4 Spatial distribution of water erosion in China (sourced from the first national water resources census)

Fig. 14.5 Changes in area of water erosion in China from 1999 to 2010

erosion area increased by 67,800 km2 in four provinces: Jilin, Guangdong, Guangxi, and Hainan. Water erosion area increased by 10.1% in Jilin Province due to the predominance of long slope cropland (generally less than 5°) and a lack of conservation practices. Water erosion area in Guangdong and Guangxi increased from 4.4% and 6.1% in 1999 to 21.3% and 11.9% in 2010, mainly due to the planting of forest. In the 1999 survey, based on remote sensing data, only vegetation canopy cover was considered, whereas in the 2010 survey, surface cover was also used to estimate the area of forest planted. For the same reason, the water erosion area in Hainan Province increased from 0.6% to 6.2% due to a large increase in orchard cover, rising from 14.6% in 1999 to 48.2%, with 60.3% of the province’s water erosion occurring on orchard land.

14

Water Erosion and Its Control in China

Fig. 14.6 Reduction in water erosion area by province from 1999 to 2010

Fig. 14.7 Percentage of reduction area to total water erosion area by province from 1999 to 2010

193

194

14.2

Y. Xie and Z. Gu

Water Erosion Control

Over China’s lengthy history of cultivation and diverse agricultural management, many soil conservation practices have been implemented. They can be classified into three types, based on their mechanisms of soil erosion control. Conservation planning and projects have been tailored to these three measurement groups.

land quality through conservation tillage. Under the Conservation Tillage Project Construction Plan (2009–2015), 6000 pilot conservation tillage pilot regions had been built by 2016, and about 113,333 km2 of new conservation farming area will soon be developed. The main measures implemented are cropland rotation, cropland fallow farming, and no-till farming.

14.2.2 Soil Conservation Measures in Provinces 14.2.1 Soil and Water Conservation Measures in China The three categories of soil and water conservation measures are vegetation cover and biological control, engineering control, and conservation control. Vegetation cover and biological control describe the protection of the soil by vegetation management, such as ecological restoration, the planting of trees or grass, and the conversion of cropland to forest and grassland (also called “grain for green”). Engineering control entails the use of mechanical or architectural measures to flatten slope terrain, shorten surface runoff path length, and increase infiltration to reduce soil erosion. Terraces are built to control inter-rill and rill erosion from cropland, and level steps, horizontal ditches, bamboo ditches, fish-scale pits, or large fruit tree pits are constructed on orchard land and among newly planted trees. Measures taken to control gully erosion include gully head conservation and the construction of check dams and other dams to form farmland. Conservation tillage reduces soil erosion from cropland by cultivation or cropping management, such as contour planting, contour ridge and furrow planting, strip intercropping, hole planting, drought-resistant productive ditch construction, the creation of horizontal furrows on fallow land, grass and crop rotation, green manuring fallow land, and less-till and no-till farming. According to the 2010 erosion survey, the conservation measures implemented on slope land in China covered an area of 943,908 km2, of which the area covered by engineering measures represented 170,120 km2 and that covered by biological measures made up 773,788 km2. In terms of gully control, 58,446 check dams had been built and 928 km2 of farmland formed. In terms of biological measures, trees had been planted on an area of 522,446 km2, newly planted grass covered an area of 41,131 km2, and ecological restoration efforts covered 210,211 km2. Terrace construction, tree planting, grass planting and ecological restoration accounted for 18.0%, 55.3%, 4.4%, and 22.3% of the total measures used (Fig. 14.8). Tillage measures covered a small area and were implemented randomly across China. By the end of 2007, the total conservation tillage area in China was government emphasized ecological development and made a plan for improving

Soil conservation practices are distributed unevenly across China due to differences in geographical background, cultivation history and traditions, and economic conditions across the large country. In 10 provinces, soil conservation practices were found to have been implemented across areas larger than 40,000 km2, accounting for 64.1% of China’s total implementation (Fig. 14.9). In six of these provinces, namely Inner Mongolia, Sichuan, Yunnan, Shaanxi, Gansu, and Guizhou, soil conservation had been undertaken across areas larger than 50,000 km2. Provinces/municipalities in which conservation covered only a small area were distributed in eastern China, where alluvial plains are found, such as Beijing, Tianjin, Shanghai, Jiangsu, Hainan, and in western China, where wind erosion is predominant, such as Tibet, Qinghai, and Xinjiang. Since the 1950s, check dams have been built to deposit loess to form farmland in the Loess Plateau. The Loess Plateau comprises seven provinces—Shanxi, Shaanxi, Henan, Ningxia, Inner Mongolia, Gansu, and Qinghai—and 314 counties. In the 2010 soil erosion survey, 58,679 check dams were counted in the Loess Plateau, and 929 km2 of farmland had been formed by eroded loess. More than half of the check dams only about 20,000 km (Ministry of Agriculture of the in this region were found in Shaanxi Province. The People’s Republic of China and National

Fig. 14.8 Percentages of soil and water conservation measures in China

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Water Erosion and Its Control in China

195

Fig. 14.9 Soil and water conservation area (a) and percentage (b) for each province

Development and Reform Commission 2009). Recently, the national check dams in Shaanxi Province and Shanxi Province accounted for 86.9% of the total number of check dams in the Loess Plateau. The remaining five provinces accounted for only 13.1% of the total number of check dams in the plateau.

14.3

Water Erosion and Its Control Across Regions

Eastern China, showing humid, semi-humid, and semi-dry climate types, is a grain supply region suffering from water erosion. Erosion characteristics vary between regions due to differences in erosive factors. Six regions have been identified to guide soil conservation planning in eastern China, running from north to south: the black soil region of northeastern China, the earth-rocky mountain region of northern China, the Loess Plateau in northwestern China, the red soil region of southern China, the purple soil region of southwestern China, and the karst region of southwestern China. The water erosion status and conservation status of each region are introduced in the following sections.

the Hulunbeier Plateau. The average annual precipitation was 300–800 mm. The dominant soil types were black soil in areas with rolling hills, chernozem on plains, and grey, dark brown, and brown coniferous forest soils in mountain areas. The natural vegetation across the mountains and plateau comprised deciduous coniferous forest, deciduous needle broad leaved forest, and prairie. Most hilly areas were cultivated, and farmland covered 289,230 km2, representing 26.5% of the total land area, with slope land making up 20.3% (58,720 km2) of the total farmland area. The conservation area was 76,290 km2, including 2,168 km2 of terrace, 46,619 km2 of newly planted trees, 4826 km2 of newly planted grass, and 22,677 km2 covered by ecological restoration measures. Of the soil and water conservation measures implemented in northeastern China, tree planting was the main measure, accounting for 61.1% of the total conservation area. Ecological restoration, grass planting, and terrace construction accounted for 29.8%, 6.3%, and 2.8%, respectively, of the conservation measures implemented (Fig. 14.10).

14.3.1 Black Soil Region of Northeastern China The black soil region of northeastern China comprises two whole provinces, Heilongjiang and Jilin, and parts of Inner Mongolia and Liaoning. Its total land area was measured at 1,090,000 km2, and its soil erosion area at 253,000 km2. Five topographic zones were identified, from east to west: the Sanjiang Plain, Xiao Hinggan Mountains and Changbai Mountains, the Songnen Plain, Daxinganling Mountain, and

Fig. 14.10 Percentages of soil and water conservation measures in black soil region of northeastern China

196

14.3.2 Earth-Rocky Mountain Region of Northern China The earth-rocky mountain region of northern China comprises four whole provinces/municipalities—Beijing, Tianjin, Hebei, and Shandong—and parts of six other provinces—Inner Mongolia, Shanxi, Liaoning, Jiangsu, Anhui, and Henan. The total land area was measured at 810,000 km2, and soil erosion area at 190,000 km2. Three topographic zones were identified, from east to west: the Liaodong and Shandong hilly regions, the Liaohe and northern China plains, and the Yanshan and Taihang mountains. The average annual precipitation was 400–800 mm. The dominant soil types were cinnamon soil, brown soil, and chestnut soil. The secondary natural and planted vegetation were temperate deciduous broad leaved forest and mixed broad leaved coniferous forest. The plains and most hilly areas were cultivated, and farmland covered 322,900 km2, 39.9% of the total land area, with a slope land area of 19,240 km2, 6.0% of the total farmland area. The area covered by conservation measures was 164,222 km2, with terrace construction covering 24,196 km2, tree planting 112,529 km2, grass planting 3832 km2, and ecological restoration 23,665 km2. Of the soil and water conservation measures implemented in the earth-rocky mountain region of northern China, tree planting was the main measure, covering 68.5% of the total conservation area. Terrace construction, ecological restoration, and grass planting accounted for 14.7%, 14.5%, and 2.3%, respectively, of the conservation measures implemented (Fig. 14.11).

14.3.3 Loess Plateau in Northwestern China The Loess Plateau in northwestern China covers parts of six provinces: Shaanxi, Shanxi, Inner-Mongolia, Gansu,

Fig. 14.11 Percentages of area covered by soil and water conservation measures in earth-rocky mountain region of northern China

Y. Xie and Z. Gu

Ningxia, and Qinghai. Its total land area was measured at 560,000 km2, and its soil erosion area at 235,000 km2. Three topographic regions were identified, from north to south: the Erdos Plateau, the Shanbei Plateau, and the Guanzhong Basin. The average annual precipitation was 50–700 mm. The dominant soil types were loess soil, cinnamon soil, heilu soil, brown soil, chestnut soil, and Aeolian sandy soil. The natural vegetation was warm temperate deciduous broad leaved forest and forest steppe. The plains and most hilly areas were cultivated, and farmland covered 126,880 km2, making up 22.7% of the total land area, with a slope land area of 45,200 km2, 35.6% of the total farmland area. The conservation area was 157,551 km2, comprising 31,193 km2 of terrace, 87,339 km2 of newly planted trees, 15,838 km2 of newly planted grass, and 23,181 km2 covered by ecological restoration efforts. Of the soil and water conservation measures undertaken in the Loess Plateau in northwestern China, tree planting was the main measure, accounting for 55.4% of the total area covered by the measures. Terrace construction, ecological restoration, and grass planting accounted for 19.8%, 14.7%, and 10.1%, respectively (Fig. 14.12), of the conservation measures implemented.

14.3.4 Red Soil Region of Southern China The red soil region of southern China comprises six whole provinces/municipalities—Shanghai, Zhejiang, Fujian, Jiangxi, Guangdong, Hainan—and parts of six provinces— Jiangsu, Anhui, Henan, Hubei, Hunan, and Guangxi. The total land area was measured at 1,240,000 km2, and the soil erosion area at 160,000 km2. Three topographic regions were identified: the alluvial plain and delta of the Yangtze River and the Pearl River, the Jiangnan hilly area, and the Nanling Mountains. The average annual precipitation was

Fig. 14.12 Percentages of area covered by soil and water conservation measures in the Loess Plateau of northwestern China

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Water Erosion and Its Control in China

800–2000 mm. The dominant soil types were brown soil, red yellow soil, and red soil. The secondary natural vegetation comprised evergreen broad leaved and coniferous forest. The plains and most hilly areas were cultivated, and farmland covered 282,340 km2, 22.8% of the total land area, with a slope land area of 17,830 km2, 6.3% of the total farmland area. The area covered by conservation measures was 200,152 km2, comprising 52,591 km2 of terrace, 96,318 km2 of newly planted trees, 1063 km2 of newly planted grass, and 50,180 km2 covered by ecological restoration efforts. Of the soil and water conservation measures implemented in the red soil region of southern China, tree planting was the main measure, accounting for 48.1% of the total conservation area. Terrace construction, ecological restoration, and grass planting accounted for 26.3%, 25.1%, and 0.5%, respectively (Fig. 14.13), of the total conservation measures implemented.

14.3.5 Purple Soil Region of Southwestern China The purple soil region of southwestern China comprises Chongqing and parts of six provinces of Henan, Hubei, Hunan, Sichuan, Shaanxi, and Gansu. The total land area was measured at 510,000 km2, and the soil erosion area at 162,000 km2. Three topographic regions were identified, from east to west: the Qinling and Chuandong mountains, the Sichuan Basin, and Chuanxi mountains. The average annual precipitation was 800–1400 mm. The dominant soil types were purple soil, yellow brown soil, and yellow soil. The secondary natural vegetation was subtropical evergreen broad leaved forest, coniferous forest, and bamboo forest. The plains and most hilly areas were cultivated, and farmland covered 113,780 km2, 22.3% of the total land area, with slope land area reaching 62,210 km2, 54.6% of the total farmland area.

Fig. 14.13 Percentages of area covered by soil and water conservation measures in the red soil region of southern China

197

Fig. 14.14 Percentages of land covered by soil and water conservation measures in the purple soil region of southwestern China

The area covered by conservation measures was 139,779 km2, comprising 28,410 km2 of terrace construction, 68,318 km2 of tree planting, 1213 km2 of grass planting, and 41,838 km2 of ecological restoration. Of the soil and water conservation measures implemented in the purple soil region of southwestern China, tree planting was most significant, accounting for 48.9% of the total area covered by these measures. Ecological restoration, terrace construction, and grass planting accounted for 29.9%, 20.3% and 0.9%, respectively (Fig. 14.14), of the conservation measures implemented.

14.3.6 Karst Region of Southwestern China The karst region of southwestern China comprises two whole provinces, Yunnan and Guizhou, and parts of Sichuan and Guangxi. Its total land area was measured at 700,000 km2, and its soil erosion area at 204,000 km2. Three topographic regions were identified, from east to west: the Guixi Mountains, the Yungui Plateau, and the Hengduan Mountains. The average annual precipitation was 800–1600 mm. The dominant soil types were yellow soil, yellow brown soil, red soil, and latosolic red soil. The natural vegetation comprised tropical and subtropical evergreen broad leaved and coniferous forest. The plains and most hilly areas were cultivated. Farmland made up 132,780 km2, 19.0% of the region’s total land area, and slope land made up 72,200 km2, 54.5% of the total farmland area. At the time of the survey, the area covered by conservation measures was 143,500 km2, comprising 30,682 km2 of terrace construction, 78,805 km2 of tree planting, 3230 km2 of grass planting, and 30,783 km2 of ecological restoration. Of the soil and water conservation measures implemented in the karst region of southwestern China, tree planting was most significant, accounting for 54.9% of the total area covered by these measures. Ecological restoration, terrace construction, and grass

198

Fig. 14.15 Percentages of soil and water conservation measures in the karst region of southwestern China

planting accounted for 21.5%, 21.3%, and 2.3%, respectively (Fig. 14.15), of the conservation measures implemented.

References Chinese Water Conservancy (2010) The first national water resources census training materials, no. 6: survey of soil and water conservation. Hydropower Press, Beijing, China Fu BJ, Wang S, Liu Y et al (2016) Hydrogeomorphic ecosystem responses to natural and anthropogenic changes in the loess plateau of china. Annu Rev Earth Planet Sci 45(1):223–243 Gao HD, Pang GW, Li ZB et al (2017) Evaluating the potential of vegetation restoration in the Loess Plateau. Acta Geogr Sin 72 (5):863–874 Guo SY, Li ZG (2009) History and achievements of soil conservation monitoring in China. Sci Soil Water Conserv 7(5):19–24 Huang BW (1995) The lessons of soil erosion zoning map in the middle Yellow River Basin. Chin Sci Bull 12:15–21

Y. Xie and Z. Gu Liu BY, Zhang KL, Xie Y (2007) Development of Chinese soil loss equation, CSLE. Abstract from the annual meeting of the soil and water conservation society. Saddle brook Resort, Tampa, Florida. Liu JS (1953) Preliminary analysis of Tianshui soil and water conservation test. Chin Sci Bull 12:59–65 Liu BY, Liu YN, Zhang KL et al (2013) Classification for soil conservation practices in China. J Soil Water Conserv 27(2):80–84 Liu XF, Yang Y, Ren ZY et al (2013) Changes of vegetation coverage in the Loess Plateau in 2000–2009. J Desert Res 33(4):1244–1249 Lowdermilk WC (1953) Conquest of the land through seven thousand years. United States Department of Agriculture Ministry of Agriculture of the People’s Republic of China and National Development and Reform Commission (2009) Conservation tillage project construction plan Olson TC, Wischmeier WH (1963) Soil-erodibility evaluations for soils on the runoff and erosion stations. Soil Sci Soc Am J 27(5):590–592 Tang KL (2004) Soil and water conservation in China. Sciences Press, Beijing The Ministry of Water Resources of the People’s Republic of China and National Bureau of Statistics of the People’s Republic of China (2013) National water resources census: report of the first national water resources census. China Water and Power Press, Beijing Wang ZG, Zhang C, Ji Q et al (2017) Soil and water conservation regionalization and its application in China. Sci Soil Water Conserv 14(6):101–106 Wischmerie WH, Smith DD (1965) Predicting rainfall-erosion losses from cropland east of the rocky mountains: a guide to conservation planning. USDA Agricultural Handbook, No. 282 Wischmeier WH, Smith DD (1978) Predicting rainfall erosion losses. Agriculture Handbook No. 537. USDA Science and Education Administration, Washington, DC Xie Y, Zhang WB, Liu BY (2002) Rainfall erosivity estimation using daily rainfall amount and intensity. Sci Geograph Sinica 6:53–56 Zhang BQ, Wu PT, Zhao XN (2011) Detecting and analysis of spatial and temporal variation of vegetation cover in the Loess Plateau during 1982–2009. Trans CSAE 27(4):287–293 Zhang KL, Peng WY, Yang HL (2007) Soil erodibility and its estimation for agricultural soil in China. Acta Pedol Sin 44(1):7–13

Aeolian Desertification Status and Its Control in China

15

Tao Wang, Guangting Chen, Halin Zhao, and Honglang Xiao

15.1

Introduction

Desertification in China mainly includes the following types: soil erosion, aeolian desertification and salinization. Desertification in most parts of northern China is mainly manifested in land aeolian desertification. Aeolian desertification is defined as land degradation in arid, semiarid and parts of semi-humid regions with the occurrence of blown sand activities (deflation, ground surface coarsening, and sand dune formation, etc.) on former non-desert areas as the main mark resulting from various factors including overusing land and upsetting the fragile ecological balance under the conditions of dry and windy climate and loose sand surface (CCICCD 1994). Land aeolian desertification is not only an important ecological problem, but also a critical economic and social problem, which hampers the sustainable development of Chinese economy and society. Firstly, it upsets the ecological balance, results in environmental deterioration and reduction of land productivity, affects the livelihood of people in aeolian desertification-prone regions and aggravates their degree of poverty. Secondly, it leads to the loss of large areas of productive lands. Finally, it poses a serious threat to rural communities, transport lines, water projects, mining and industrial infrastructures, national defense bases, as well as agricultural and industrial productions. At the beginning of P. R. China founding in 1949, the State started the process of combating aeolian desertification. Although significant achievements have been made by now in aeolian desertification control, only a small proportion of the desertified land has been improved, and in most regions the situation has become worse (Dong and Gao 1993; Liu 1982a, b; SSDER et al. 1980; TRDCCP 1998; Zhu and Liu 1981; Zhu 1992, 1999a; Zhu et al. 1989, 1998). T. Wang (&)  G. Chen  H. Zhao  H. Xiao Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China e-mail: [email protected]

According to statistical data, the land area affected by water erosion, wind erosion, aeolian desertification and salinization occupies about one third of Chinese terrestrial area, of which desert, gravel desert (gobi), wind-eroded land and aeolian desertified land cover 1.67
106 km2, accounting for 17.4% of China’s total land area. There are 38.57
104 km2 of aeolian desertification land, accounting for 44.3% in 83.7
104 km2 of all kind of desertified land (Dong et al. 1995; Wang et al. 2004a, b; Zhu and Chen 1994). With the accelerating development of aeolian desertification, the frequency of strong dust storms greatly increased. The frequency of strong dust storms in northern China has increased from 5 times per year in 1950s to 8 times per year in 1960s, 13 times per year in 1970s, 14 times per year in 1980s, and 23 times per year in 1990s. Dust storms directly damage northwest and northern China and can affect southern China or even the whole East Asia.

15.2

Aeolian Desertification Category

15.2.1 Index and System of Aeolian Desertification Category At present, there are no uniform principle, index and system of aeolian desertification category in China. There are several category systems commonly used in actual practices: (1) From the point of aeolian desertification development phase (Table 15.1) (Zhu and Liu 1981; Zhu 1999b). It is the most popular way. When judging the degree of aeolian desertification in certain area from the view of ecology, we also consider changes of potential land productivity, biomass (including changes of plant structure and rate of vegetation cover) and energy transfer efficiency in biological system (Table 15.2).

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_15

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Table 15.1 The symbols of aeolian desertification land development Types

Percentage of aeolian desertification land

Features of shapes

Typical areas

Aeolian desertification-prone land

5

Patches of shifting sand sparsely scatter in farmland and around wells and residential area

Xilingol Steppe, Northern Ulanqab Steppe, etc

Ongoing aeolian desertification land

6–25

Speckles of shifting sand or blown land, farmlands suffered wind erosion

Southern Ulanqab Steppe, Qahar Steppe, northern Horqin Steppe

Intensively developed aeolian desertification land

26–50

Sheets of shifting sand dunes and blown shrub sand dunes, interlaced with fixed and semi- fixed sand dunes

Onqin Daga Sandy Land, Eastern Horqin Sandy Land, etc

 51

Predominant shifting sand dunes distribute densely

Western Horqin Sandy Land between Laoha River and Bairin Bridge, etc

Severe aeolian desertification land

Table 15.2 Ecological indicators of aeolian desertification degree

Degree

Vegetation cover/%

Land productivity/%

Latent

Above 60

Above 80

Ratio of output to input/% > 80

Biomass/[t/ (haa)] 3.0–4.5

Ongoing

59–30

79–50

79–60

2.9–1.5

Intensively developing

29–10

49–20

59–30

1.4–1.0

Severe

9–0

19–0

29–0

0.9–0.0

(2) According to configuration changes (Table 15.3). When estimating the degree of aeolian desertification somewhere, we usually consider surficial “instant” static characteristics reflecting the degree of aeolian desertification, but we don’t know how it was or how it will be. We determine the degree of aeolian desertification according to actual status, and concepts which can reflect actual status of aeolian desertification are used to name concrete aeolian desertification degree. (3) Taking aeolian desertification process and land types into consideration (Table 15.4). (4) According to the development status (Table 15.5).

15.2.2 Synthetic Indicator System of Aeolian Desertification Monitoring by Remote Sensing Although a set of indicator system of aeolian desertification had been established by FAO and UNEP in 1984, it is still needed to make a practical indicator system for regional desertification monitoring and classification because of big differences from place to place. The indicators selected for aeolian desertification classification should be representative

and applicable. An indicator should be a statistic quantum or represent an environment phenomena related to aeolian desertification processes, which represents an existing specific environment condition (Wang et al. 1998). The indicators should have following features: ① contain clear information and easy to get from observations; ② sensitive to the changes of aeolian desertification status; ③ suitable to be used repeatedly; ④ go through quantitative check. According to the characteristics of aeolian desertification in northern China, we have established a universal aeolian desertification indicator and classification system, which take surface feature variations as main factors and meanwhile consider the changes of soil, vegetation and eco-system (Table 15.6). The selected indicators have a common representativeness and their aeolian differences are easy to distinguish in monitoring and evaluating aeolian desertification processes in northern China. With the development of aeolian desertification, the land potential productivity and biological production including vegetation cover are changed. We can take these changes as supplementary indicators to evaluate aeolian desertification degree (Table 15.7). In fact, in the remote sensing monitoring practice, the percentage of eroded land or shifting sand areas and its changes in a certain period are taken as main indicators and

15

Aeolian Desertification Status and Its Control in China

Table 15.3 Synthetical landscape symbols of all degrees of aeolian desertification land

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Aeolian desertification degree

Synthetic landscape symbols

Light aeolian desertification land

1. Blowouts appear at windward slope, with shifting sand depositing at leeward slope; rate of vegetation cover is 30–60%; Areas with speckles of shifting sand occupy 5–25% 2. Different scales of shrub sand mounds appear, shrubs grow luxuriantly and thickly 3. A thin layer of sand deposits at the Earth’s surface, even with gravels outcropped 4. In Spring, farmland is eroded by wind, with less than 50% loss of humus and output is 50%-80% of original yields 5. Blowouts appear where fine soil is thick, with certain vegetation cover

Moderate aeolian desertification land

1. The difference between blown slope and slip slope is obvious; vegetation cover is 10–30%; area of shifting sand account for 25–50% 2. The whole sand mound can’t be covered by shrub complete, with shifting sand’s occurrence at windward slope 3. Small patches of shifting sand appear at loess area, with much coarse sand and gravel at the surface, but still with sparse plant, vegetation cover is 10– 30% 4. Productivity is decreased due to wind erosion, with more than 50% loss of humus and less than 50% of original output 5. Blowouts are mostly bare, small-size steep ridges emerge at the ground surface

Severe aeolian desertification land

1. The whole sandy desertified area is shifting-sandy-land-like, with more than 50% of shifting sand, sparse vegetation, and vegetation cover is less than 10% 2. Gravel desertified area takes on a Gobi-like look, vegetation cover is below 10%, farmlands with gravel desertification occurrence are deserted 3. Humus layer is almost blown away completely, calcic horizon or soil parent material is outcropped and most farmlands are deserted 4. Soil residue by wind erosion appears at Earth’s surface

others as supplementary indicators. This is because the change of eroded land or shifting sand area is a combined result of vegetation cover, biological production, soil properties and water content etc. It is easy to judge and convenient to use during the aeolian desertification monitoring in northern China. This means that our classification system mainly relies on the direct information of ground vegetation cover, species of plants and micro topographic features. Based on this indicator system of aeolian desertification monitoring, the four types of aeolian desertification in northern China have the following features: (1) Slightly aeolian desertified land: ① The blowouts appear on windward slopes of sand dunes and there are some accumulative shifting sands on leeward slopes, vegetation cover is 30–50%, patches of shifting sands occupy 25%; ② Shrubs grow well, sand mounds of different sizes appear around shrubs; ③ There is a thin layer of shifting sands on land surface; ④ The ridges of cultivated field are eroded and sands are accumulated between ridges, and humus layer lose of soil is less than 50%; ⑤ Crop yield is 50–80% of initial stages of

cultivation; ⑥ Shallow blowouts occur in sandy area but some vegetation still exists, the blowouts are gradually transformed without obvious steep bench. (2) Moderately aeolian desertified land: ① An obvious differentiation between eroded slope and slip face appears, vegetation cover is 15–30%, the area of shifting sand occupy 25–50%; ② Leaved shrubs cannot entirely cover sand mounds and there are shifting sands on windward side of sand mounds; ③ Small patches of shifting sand occur in loessial farmland or land surface covered by coarse sands or gravels, but a few vegetation still exist with a cover age of 10–30%; ④ There is obvious wind erosion in cultivated land, less than 50% of humus layer has been blown away, crop yield is 50% of initial stages of cultivation; ⑤ Blowouts are mostly exposed and ridges are easy to be distinguished. (3) Severely aeolian desertified land: ① Sandy land is in a semi-fixed state, the area of shifting sands exceeds 50%, vegetation coverage is less than 15%; ② Gobi landscape occurs, vegetation cover is smaller than 10%; ③ Humus layer of soil is eroded and almost blown away, Calcic horizon is exposed, most desertified croplands

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Table 15.4 Aeolian desertification categories in northern China Types degree

A Reactivation of fixed sand dunes

B Aeolian desertification of shrubs

C Gravel aeolian desertification

D Badland aeolian desertification

E Aeolian desertification of farmland

Distributing area

Sandy lands in eastern China; margins of deserts or riverbanks deep in desert in western China

Deserts in western China or margins of sandy lands in eastern China; central Inner Mongolian Plateau

Peripheral area of Gobi; central and western part of Inner Mongolian Plateau

Lop Nur, peripheral area of Altun Mountain where Yardang landform distributes; southeastern part of Inner Mongolian Plateau (Bashang in Hebei Province)

Farm region in eastern steppe; northern part of Loess Plateau

1 Original status (aeolian desertification-prone land)

1a Fixed sand dunes or oases, farmlands

1b Dry steppe or desert steppe, steppification desert

1c Desert steppe or steppification desert

1d Dry steppe or desert steppe, steppification desert

1e Dry farmlands

2 Slight aeolian desertification land

2a Blowouts appear at the windward slope; patchy shifting sand occupies 5–25%; with more than 90% of original vegetation cover

2b Shrubs flourish; shifting sand deposits under shrubs

2c Gravels are getting concentrated at the ground surface

2d Shallow blown pits merge at the ground surface but without steep ridges

2e There is deposited sand in farmland in Spring, with obvious trace of wind erosion

3 Moderate aeolian desertification land

3a The difference between blown slope and slip slope is obvious; area of shifting sand account for 25– 50%

3b The whole sand mound can’t be covered by shrub complete, with shifting sand’s occurrence at windward slope

3c There are much coarse sand and gravels at the surface, but still with sparse plant, vegetation cover is more than 25%. The landscape is gravel steppe

3d Most blowouts are bare, obvious small-size steep ridges emerge at the Earth’s surface

3e Small patches of shifting sand appear in loessial farmlands; productivity is decreased due to wind erosion, with more than 50% loss of humus

4 Severe aeolian desertification land

4a Sandy land is semi-shifting, area of shifting sand exceeds 50%, with less than 50% of original vegetation cover

4b Large patches of shrubs are dead; vegetation cover is below 25%, area of shifting sand exceeds 50%

4c Earth’s surface is covered by gravels completely, with little sand in small holes among gravels, vegetation cover is 10%-25%

4d Soil residue by wind erosion appears at Earth’s surface, with sparse vegetation at interdune area, farmlands with gravel desertification occurrence are deserted

4e Humus layer is almost blown away completely, calcic horizon or soil parent material is outcropped and most sandy desertified farmlands are deserted

5 Very severe aeolian desertification land

5a Shifting sand dunes or sandy land, with vegetation cover less than 10%

5b Undulated shifting sandy land, with vegetation cover less than 10%

5c Gobi; vegetation cover is less than 10%

5d Yardang landscape

5e Flat sandy land or gravel land; vegetation cover 0.25 0.25–3.0 > 3.0

Table 15.6 Classification and indicators of aeolian desertification degrees

Degree

Blown-sand area /%

Annual expansion area /%

Annual reduction of biomass /%

Vegetation cover*/%

Slight (L)

7.5

Very severe (VS)

> 50

>5

*

Vegetation cover is calculated by projection method and the vegetation cover of local primary landscape is regarded as 100%

Table 15.7 Supplementary indicators for aeolian desertification classification

Degree

Soil deflation thickness /cm

Soil deflation rate /[t/(haa)]

Overload population/%

Overload livestock/%

Slight (L)

20

> 20

> 3.0

> 31

> 31

Very severe (VS)

are abandoned; ④ Deflation mounds and pillars appear on land surface. (4) Very severely aeolian desertified land: ① Land loses their productivity completely; ② A mobile sand dune landscape occurs in sandy lands; ③ Gobi landscape occurs in gravel lands; ④ Yadangs occur in wind-eroded lands.

15.3

Accumulative thickness /cm

Range and Types of Aeolian Desertification in China

Drought is a cause of aeolian desertification of lands, but essentially, irrational human behavior is the main cause of aeolian desertification. In China, only 5.5% of total 38.57
104 km2 aeolian desertification land was caused by sand dune’s advancing. Aeolian desertified lands don’t

include sandy desert, Gobi, salt desert and cold desert formed in geological period. According to the report of State Environmental Protection Administration of China (SEPA 1999), there are 83.7
104 km2 of all kinds of desertification lands, accounting for 8.7% of total territory. Thereinto, there are 38.57
104 km2 of aeolian desertification lands, accounting for 44.3% of desertified land. The report also showed that there are 141
104 km2 of lands susceptible to desertification, there into the area of land susceptible to aeolian desertification is 53.7
104 km2. Desertified land and land susceptible to desertification amount to 224.7
104 km2, and land of aeolian desertification and threatened by aeolian desertification amount to 90.8
104 km2. In addition to 219.1
104 km2 of sand desert, Gobi and blown land account for 22.82% of the total area of continental territory (Fig. 15.1). To sum up, the distributions of aeolian desertification land are not limited in regions with drought index value of

204

T. Wang et al.

Fig. 15.1 Map of desert and aeolian desertification land in northern China

0.50–0.65 in China, but in all kinds of natural belts, which show aeolian desertification is the product of interaction between intensive human activities and fragile ecological environment, and irrational human activities that made environment degraded toward desert-like landscape. There was 38.57
104 km2 of aeolian desertification land in northern China, there into, light aeolian desertification land was 13.95
104 km2, accounting for 36.1% of total aeolian desertification land; moderate aeolian desertification land was 9.98
104 km2, occupying 25.9%; severe aeolian desertification land was 7.91
104 km2, 20.5%; very severe aeolian desertification land was 6.75
104 km2, 17.5% (Fig. 15.1). Compared with the results of aeolian desertification land monitoring in the middle and late 1980s, in 2000, the percentage of light aeolian desertification land was reduced, that of moderate aeolian desertification land kept stable, but the percentage of severe aeolian desertification increased. This status is consistent with the principles of aeolian desertification development, and also conforms to principles of aeolian desertification control that parts of light aeolian desertification land should be controlled first and get rehabilitated.

15.4

The Spatial Characteristics of Aeolian Desertification in China

15.4.1 Regional Differences Northwest China is located in the hinterland of Asian continent and the climate is hypo-arid continental climate here. The climate in eastern China is controlled by Eastern Asian Monsoon. So, the aeolian desertification characteristics show obvious region differences. 1. Arid Regions in Western China On the natural condition of hypo-arid in western China, both natural and artificial vegetation much depend on water. Rivers supplied by precipitation and snow from mountains around desert are the base of sand desert oasis’s existence. The decrease of river water, whether it’s caused by natural or human factors, can determine the development of aeolian desertification land in oases. Besides, local people’s destroying vegetation around oases accelerates the development of land aeolian desertification in oasis.

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Aeolian Desertification Status and Its Control in China

205

Because water resource is limited in western China, the reasonable assignment of water between upper and lower reach of continental river is very important. There are three regions that give typical examples of land aeolian desertification development due to water use conflict in a whole river basin.

Box 15.1 The opposed development of two oases at upper and down reaches of the Shiyang River basin in Gansu Province The Shiyang River converged by 8 rivers all originating from the Qilian Mountains fosters Wuwei Oasis first, passes by Hongyashan fault zone and irrigates Minqin Oasis at last (Fig. 15.2). Because the water resource is limited in the Shiyang River Valley, the phase of opposed development that one oasis flourishes and the other must wane has been alternatively formed in history. From the later of the Western Han Dynasty when the Wuwei Oasis took shape through the Tang Dynasty, the Wuwei Oasis gradually became the largest and most flourishing city in Hexi region and the surrounding agriculture was also well developed. The increase of water use at the upper reach of Shiyang River made rivers dry up, lakes shrink, oasis decline and aeolian desertification develop quickly in the Minqin Oasis. And years of war made these farmlands abandoned and suffer from intensive process of aeolian desertification. From the end of the Tang Dynasty to the beginning of the Yuan Dynasty, Hexi region suffered from wars among several tribes and the Minqin Oasis was used for grazing by nomads. At the same time, the Wuwei Oasis also declined, so water for irrigation decreased. The water at the lower reach of the Shiyang River recovered. Lakes also recovered partly. When there was water, aeolian desertification was reversed. The policy that army cultivated farmland where they guarded was implemented during both the Ming and Qing dynasties. And the history of exploiting the Shiyang River Valley replayed, namely agriculture developed and Wuwei Oasis expanded, at the same time, Minqin Oasis receded southwardly. In the period of the Republic of China, there was 74.2% of plowland in Hexi can be irrigated in 1944, accounting for only 35.5% of Hexi region, because of lacking of efficient and appropriate management and distribution of water resources among the whole drainage basin and decision failure. To make up the lack of precipitation, local people began to pump out groundwater to irrigate farmlands. By the middle 1970s, one to two billion cubic metres of water are

Fig. 15.2 Image of the Shiyang river basin

over exploited per year, which resulted in the decline of the water table significantly. Nowadays, the water table in Minqin declined to 12–15 m under ground surface, which lead to the downfall of sand-fixing plants and worsened the development of aeolian desertification. Since the 1960s, there was totally 2.52
104 ha of abandoned farmland due to lack of water (Zhu and Chen 1994).

Box 15.2 The opposed development between the upper-reach-located oasis and the lower-reachlocated sandy desertified land in the Tarim River Basin of Xinjiang Province The Tarim River is the longest continental river in China, its course swings 2200 km from the Yarkant River to the Tetima Lake (Fig. 15.3). The main stem of the Tarim River, also customarily called the Tarim River, refers to the section from the joint point of the Aksu River, Hotan River and Yarkant River to the Taitema Lake, with a length of 1280 km. According to documentary records, the Tarim River was ever perennial. In 1759 AD, foods could be shipped from Xayar to Shache through the Tarim River; Swedish explorer Sven Hedin (1865–1952) traveled from the upper reach of the Yarkant River to lower Tarim River by a large wooden ship during winter in 1899 through the spring of the next year; By the 1960s, the Tarim River was still perennial and river water could eventually flow into the Tetima Lake. Since the early 1960s, only flood water could reach the Tetima Lake. After the 1970s, the dramatically increased human

206

activities increased the use water in the middle reach of the Tarim River. A total of 2.15
1010 m3 water was consumed in the section from the Tarim River Dam to Kala Station, with the largest water consumption rate of 6.83
106 m3 per kilometer in the Tarim River Basin. Simultaneously, water loss through evaporation and leakage was great. At that time, local people accidentally breached river bank to divert water extensively for farmland irrigation, resulting in river course changing and a lot of water flowing into nearby lakes, swamps, reservoirs, desert and holes. The lower reach region of the Tarim River was more arid than ever before even though the runoff was abundant in the upper reaches in year 1986. At present, there are serious environmental degradation problems in the lower reach region of the Tarim River. One, sandy desertification intensively develops, i.e., abandoned plots are a common sight in irrigation area, being prone to aeolian desertification land; a large area of Populus euphratica forest died; fixed sandy dunes reactivated and encroached farmlands; lakes dried up; the degree of mineralization of lakes, rivers and ground water all increased; the biodiversity declined (Fan 1993).

T. Wang et al.

Fig. 15.3 Sketch map of the Tarim River system

Box 15.3 Water use conflict along the Heihe River Valley passing three provinces of the Northwest China The Heihe River originates from the Qilian Mountains, flows through the Qinghai, Gansu, and Inner Mongolia provinces, passing a distance of 821 km and river water finally goes into the Juyanhai Lake in the Ejin Banner of western Inner Mongolia (Fig. 15.4). The history of exploitation at the upper reach of the Heihe River Valley can be dated back to 100 AD; the agricultural development at the lower reach has formed a famous “Black City Cultures”. In the recent 30 years, with the population increasing, the conflict of water use is prominent among different administrative areas. Consequently, both the eastern and western Juyanhai lakes in lower reach of the Heihe River dried up, the area of natural forest and grassland reduced sharply, and the frequency of all kinds of catastrophic climate increased, exhibiting that the ecological environment deteriorated severely. At the middle reach, pastureland and the natural vegetation of Zhangye agricultural oases in Gansu Province degraded, land aeolian desertification and salinization are very serious (Liu 1982a, b). Even in the upper Qilian Mountainous area

Fig. 15.4 Boundary of the Heihe River Basin (Pan and Tian 2001)

of the Qinghai Province, the area of natural forest reduced, the capacity of headwater conservation decreased, and land desertification is obvious. A part from the reason of water resource scarcity, desert expansion also can result in Aeolian desertification. A typical example is that the southward advancing of the Taklimakan Desert in southern Xinjiang has made the oases in

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Aeolian Desertification Status and Its Control in China

front of the Kunlun Mountains shrink seriously and most evidently in Hotan region. Within the recent 50 years, the area of sandy desertified land in Hotan mounted up to 1.67
104 ha, thereinto, sandy desertified farmland was 0.58
104 ha, and the Qira County site was obliged to be moved for 3 times. Along the rim of the Taklimakan Desert, there is an unclosed circle of land aeolian desertification, with an area of 1.296
105 ha, was caused by modern shifting sand encroachment (Table 15.8).

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of environmental degradation is from quantitative to qualitative (Fig. 15.5).

15.4.2 Spatial Distribution Research on aeolian desertification in China began in the late 1970s, many results has summarized its spatial distribution characteristics (Fan 1993; Zhou 1989; Zhu and Liu 1981; Zhu and Chen 1994; Zhu 1999b):

2. Semiarid Regions in Eastern China In the latest 50 years, aeolian desertification developed intensively in the semiarid regions of eastern China, where 85% of modern aeolian desertification lands are concentratedly distributed. To investigate its germ, the most essential is that the pressure exerted by human economic activities exceeds the environmental carrying capacity. As a result, desert-like landscapes appeared on former non-sandy-desertification lands. A typical example lies in the transitional zone between grassland and farmland in eastern China, this fragile ecotone stretches from the Horqin Steppe, along inside and outside of the Great Wall to the Mau Us Sandy Land and the southern part of Yanchi County in Ningxia Province. The ecological frangibility in this ecotone is determined by the local fragile natural conditions (Zhu and Chen 1994): ① great variability of annual precipitation, results in instability of water condition; ② thick and loose surface sandy sediments or even sand bed, form fragile soil condition; ③ gales blow frequently in a year producing atrocious weather condition. On the background of local fragile natural conditions, irrational land use has accelerated the expanding rate of aeolian desertification in the ecotone. Development of aeolian desertification in semi-arid regions is substantially a result of environmental degradation caused by economic development at the expense of ecological environment. The process Table 15.8 Land area encroached by sand dunes along the rim of modern Taklimakan Desert

(1) Aeolian desertification lands are concentrated in semi-arid regions (Table 15.9). Aeolian desertification land was 20.13
104 km2, accounting for 52.2% of total aeolian desertification land in China. (2) Aeolian desertification lands in arid region are fleckily distributed around oases and in the marginal area of Gurbantunggut desert where there are mainly fixed and semi-fixed sand dunes (Table 15.10). The area of sandy desertified land amounts to 12.2
104 km2, accounting for 31.4% of the total in China. (3) Aeolian desertification lands are mainly scattered in proluvial fans and along old riverbed banks in semi-humid regions (Table 15.11). Area of aeolian desertification land is 2.47
104 km2, accounting for 6.4% of total aeolian desertification land in China. Because of local semi-humid climate, aeolian desertification landscape is generally manifested in blown sand landform in dry seasons such as in winter and spring, but it takes on a farmland view in summer and autumn, when characteristics of blown sand movement are not obvious. So, aeolian desertification land scape changes seasonally. (4) Aeolian desertification lands under the wind force in humid regions are concentrated in sandy lands along riverbanks and in seashores. Aeolian desertification land in humid regions of southern China has the

Sites

Modern sand dunes encroached area/km2

Percentage/ %

Southwestern edge (Yecheng-Hotan)

231

17.8

Middle southern edge (Qira-Qiemo)

279

21.5

Southeastern edge (Qiemo-Ruoqiang)

132

10.2

Southern edge of eastern part (lower Tarim River)

302

23.3

Northern edge

170

13.1

Eastern part of Buguli and Tuokelake Desert

182

14.1

Total

1296

100

208

T. Wang et al.

Fig. 15.5 Process of aeolian desertification in transitional zone between grassland and farmland in semi-arid region

following characteristics: ① Seasonal changes are more obvious; ② The history of evolvement is short, but at rapid developing rate; ③ Human over cutting makes ground bare in winter, which aggravates the blown sand movement; ④ sand is coarse, with good sorting, and high threshold velocity is required; ⑤ Sand source is limited and landform is simple.

(5) Aeolian desertification lands fleckily scatter along riverbanks in high tundra zone. Aeolian desertification land generally shows a patchy and scattered distribution pattern in high tundra zone, and it is mainly distributed in valleys of Brahmaputra, the Lhasa River and Nianchu River. Shifting sand caused by over grazing and over cutting is interruptedly distributed. Aeolian

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Aeolian Desertification Status and Its Control in China

Table 15.9 Counties (banners), cities influenced by aeolian desertification in semi-arid zone

209

Geographic units

Influenced cities or counties (banners)

Hulun Buir steppe

Inner Mongolia: Manzhouli, Hailar, Xin Barag Youqi, Xin Barag Zuoqi, Xin Barag Qi

Horqin steppe

Inner Mongolia: Horqin Zuoyi Zhongqi, Horqin Zuoyi Houqi, Horqin Youyi Zhongqi, Jarud Qi, Holinggol City, Tongliao City, Kailu, Naiman Qi, Hure Qi, Aluhorqin Qi, Wengniute Qi, Bairin Yoqi, Bairin Zuoqi, Linxi, Hexigten Qi, Aohan Qi, Chifeng City Liaoning: Zhangwu, Kangping, Faku Jilin: Shuangliao

Xilin Gol steppe and Onqin Daga steppe

Inner Mongolia: Dong Ujimqin Qi, Xi Ujimqin Qi, Xilinhot City, Abaga Qi, Sonid Zuoqi, Sonid Youqi, Hexigten Qi

Qahar steppe

Inner Mongolia: Zhenglan Qi, Duolun, Zhengxiangbai Qi, Xianghuang Qi, Taipusi Qi

Bashang area in Hebei Province Ulanqab steppe

Hebei: Weichang, Fengning, Zhangbei, Guyuan, Kangbao, Shangyi Inner Mongolia: Huade, Shangdu, Qahar Youyi Houqi, Qahar Youyi Zhongqi, Siziwang Qi, Damao Qi, Guyang, Wuchuang

Qianshan area and tumd plain in Ulanqab Meng

Inner Mongolia: Qahar Youyi Qianqi, Fengzhen, Xinghe, Liangcheng, Helinge’er, Qingshuihe, Suburb of Baotou City, Tuoketuo

Northwestern Shanxi Province

Shanxi: Zuoyun, Youyu, Pinlu, Pianguan, Hequ, Baode, Suburb of Datong City, Huairen, Shanyin, Shuo County, Shenchi, Wuzhai, Kelan, Lan County, Xing County

Erdos steppe and Mu Us sandy land

Inner Mongolia: Dalad Qi, Zhunge’er Qi, Dongsheng City, Yijinhuoluo Qi, Hanggin Qi, Otog Qi, Otog Qianqi, Uxin Qi Shaanxi: Shenmu, Fugu, Yumu, Hengshan, Jia County, Dingbian, Jingbian Ningxia: Yanchi

Sandy land on the eastern side of Yellow river in Ningxia autonomous region

Ningxia: Lingwu Gansu: Huan County

Source Zhu and Chen (1994)

desertification land developed around towns in Nimula, Naqu of northern Tibetan Plateau and Shiquanhe town in A’li area, which was mostly related to local construction of infrastructure and over cutting.

15.5

The Temporal Characteristics of Aeolian Desertification in China

15.5.1 Temporal Distribution Aeolian desertification is a dynamic process, and the distributing scope and characteristics of surficial landforms are variable during different periods. With aeolian desertification in northern China as an example, the characteristics of temporal distribution of aeolian desertification are as follows.

(1) Before 1000 AD, especially in Han and Tang dynasties, aeolian desertification lands showed a specky distribution pattern and concentrated at the lower reach of continental rivers in arid region where historical ancient cities usually situated. Aeolian desertification was caused by inappropriate utilization of water resources. This kind of aeolian desertification land was 5.36
104 km2, accounting for 14.4% of total aeolian desertification land in China. (2) F rom 1100 to 1900 AD, aeolian desertification lands concentrated in semi-arid region, and it was centered on historical farming region, showing a patchy distribution pattern. Because of different way of land use (grazing or farming), there existed development and reverse of aeolian desertification land during this period. This kind of aeolian desertification land is 8.62
104 km2, accounting for 23.23% of total aeolian desertification land in China, and its occurrence and development is closely related to reclamation of farmland.

210 Table 15.10 Aeolian desertification land in arid region in northwestern China

T. Wang et al. Geographic units

Related city and county (or banner)

Junggar Basin

Xinjiang: Qitai, Mulei, Jimsar, Fukang, Miquan, Changji, Hutubi, Shawan, Suburb of Ürumqi city, Manasi, Kuitun, Jinghe, Suburb of Kelamayi city, Fuhai, Jimunai, Habahe, Bu’erjin

Tu-Ha Basin

Xinjiang: Hami, Turpan, Tuokexun, Shanshan, Barkol, Yiwu

Yili Basin

Xinjiang: Huocheng

Tarim Basin

Xinjiang: Korla, Yuli, Luntai, Kuqa, Xayar, Xinhe, Awat, Aksu, Wensu, Kalpin, Bachu, Jiashi, Yopurga, Shache, Zepu, Yecheng, Pishan, Moyu, Hotan, Lop, Qira, Yutian, Minfeng, Qimo, Ruoqiang, Artux, Shufu, Shule, Markit, Yingjisha

Hexi corridor, front Qilian Mountains and marginal area of Tengger desert

Gansu: Dunhuang, A’kesai, Subei, An’xi, Yumen, Jiayuguang, Jiuquan, Jinta, Sunan, Gaotai, Linze, Zhangye, Jinchang, Shandan, Minle, Minqi, Gulang, Wuwei, Jingtai

Yinchuang Plain and Zhongwei Basin

Ningxia: Zhongwei, Zhongning, Wuzhong, Lingwu, Qingtongxia, Yongning, Suburb of Yinchuan city, Helan, Taole, Pingluo, Shizuishan

Alxa Plateau

Inner Mongolia: EjinQi, Alxa Youqi, Alxa Zuoqi

Hetao Plain and area along Yellow River

Inner Mongolia: Dengkou, Hanggin Houqi, Linhe, Wuyuan, Urad Qianqi, Wuhai city

Inner Mongolian Plateau (Houshan area)

Inner Mongolia: Urad Houqi, Urad Zhongqi

Source Zhu and Chen (1994) Table 15.11 Counties and cities suffered from aeolian desertification in semi-humid region of north China

Provinces

Counties (cities)

Heilongjiang Province

Suburb of Qiqihar City, Du’erbote, Tailai, Gannan, Longjiang, Fuyu, Lindian, Nahe, Zhaoyuan, Suburb of Daqing City

Jilin Province

Baicheng City, Zhenlai, Da’an, Tongyu, Changling, Qianguo’erluosi, Fuyu, Qian’an, Tao’an

Beijing City

Yanqing, Changping, Huairou, Shunyi, Fengtai District, Tongxian, Daxing, Fangshan

Tianjin City

Wuqing

Hebei Province

Qian’an, Luanxian, Luannan, Leting, Lulong, Changli, Zhuoxian, Gu’an, Yongqing, An’ci, Xinle, Zhengding, Shahe, Daming, Guantao, Weixian, Linxi, Qinghe

Henan Province

Neihuang, Qingfeng, Fanxian, Taiqian, Puyang, Junxian, Huaxian, Jixian, Xinxiang, Changyuan, Yanjin, Yuanyang, Fengqiu, Suburb of Zhengzhou City, Xinzheng, Zhongmou, Suburb of Kaifeng City, Kaifeng, Weidi, Tongxu, Qixian, Lankao, Minquan, Suixian, Ningling, Suburb of Shangqiu City, Shangqiu, Yucheng, Xiayi

Shandong Province

Dongming, Heze, Juancheng, Caoxian, Dingtao, Shanxian, Jinxiang, Yutai, Juye, Yuncheng, Jiaxiang, Yanggu, Xinxiang, Guancheng, Liaocheng, Dong’e, Chiping, Linqing, Gaotang, Xiajin, Wucheng, Yucheng, Pingyuan, Jiyang, Linyi, Shanghe, Leling, Qingyun, Huimin, Wudi, Zhanhua, Binxian, Lijin, Kenli

Jiangsu Province

Fengxian, Peixian

Shaanxi Province

Dali

An’hui Province

Dangshan

Source Zhu and Chen (1994)

(3) In the twentieth century, great population pressure and frequent human activities had promoted the expansion of aeolian desertification land. Over cultivation, overgrazing and irrational development of artificial oases at upper reaches of continental rivers are the main causes

of expansion of modern aeolian desertification land. The annual increase of aeolian desertification land area in northern China was 1560 km2 during the period from the 1950s to the middle 1970s, with a rate of 1.01%; from the middle 1970s to the middle 1980s, it was

15

Aeolian Desertification Status and Its Control in China

2100 km2, with a rate of 1.47%; and it was 2460 km2 in the 1990s. What’s more, the degree of aeolian desertification got aggravated, severe aeolian desertification land accounted for 0.93% in the middle 1970s, but it was 1.77% in the middle 1980s, during the same period, moderate aeolian desertification land increased from 14.87 to 21.8%, while light aeolian desertification land decreased from 84.2 to 76.4%. It shows the degree of aeolian desertification is getting worse and worse. (4) Around the turn of 20th to twenty-first century, a large area of aeolian desertification land got rehabilitated benefited from the “grain for green” policy in Chinese strategic plan of “West Development” (TRDCCP 1998). But, in the past 20 years, many new aeolian desertification lands develop resulted from the construction of new factories, roads, railways, etc., which have destroyed the stabilization of sand surface in sand desert areas. Human activities anxious for success in “banish poverty and become rich” without consideration of the environmental capacity have also resulted the new development of aeolian desertification. For maintaining the sustainable and stable development of economy, we have to adjust our activities constantly and create a virtuous cycle of ecological environment in sandy areas.

15.5.2 Temporal Change Two large-scale investigations of aeolian desertified lands had been carried out in the mid-1970s and late 1980s by the former Lanzhou Institute of Desert Research, Chinese Academy of Science. The first investigation in the 1970s showed that there were 33.4
104 km2 of aeolian desertified lands, of which 17.6
104 km2 have been already aeolian desertified and 15.8
104 km2 are potential aeolian desertified lands. Compared with air photo data of 1950s, in northern part of China the aeolian desertified lands were expanded at rate of 1560 km2/a from 1950s to 1970s (Wang et al. 2004a, b). There are two causes for the expansion, one is dry-farming lands aeolian desertification due to over cultivation in steppes and desert steppe regions, and the other is mobilization of fixed dunes due to overgrazing and over cutting of firewood in fixed sand dune areas. In the second investigation in the 1980s, remote sensing is used as main means for the investigation and monitoring. The monitoring results indicate that there were 37.1
104 km2 of aeolian desertified lands in China, accounting for 3.86% of its total land area, distributed in arid, semiarid and semi-humid areas. From 1970s to 1980s, the aeolian desertified land was developed at a rate of 2100 km2/a (Wang et al. 2004a, b; Zhu 1999b).

211

In the 1990s, the speed of aeolian desertification expansion further increased, at a rate of 3600 km2/a from 1988 to 2000 (Wang et al. 1995, 2004a). With the application of remote sensing and GIS techniques, a larger scale investigation on the aeolian desertified land distribution, development and hazard had been made in the China. Aeolian desertification study has entered a new stage of quantitative analysis and evaluation (Liu 1996; Ma and Li 2000; Wang et al. 1994, 1998; Wang 1992; Wu 1991, 1997; Wu et al. 1997; Zhu 1999b). From the research results, aeolian desertification has developed mainly in three regions in northern China in the past 50 years (Fig. 15.6): ① Mixed farming-grazing zone of semiarid region, occupies 40.5% of total aeolian desertified lands of northern China; ② Sandy grassland zone of semiarid region, occupies 36.5%; ③ Arid oasis edge and lower reaches of inland rivers, occupy 23%. Remote sensing data also show that about 10% of aeolian desertified lands kept a stable state or exhibited a reversed trend.

15.6

Measures to Control Aeolian Desertification

15.6.1 Vegetative Method Practices at home and abroad proved vegetative or biological method to combat sand is a basic measure to fix shifting sand and control land aeolian desertification. Mechanic sand barrier (artificial sand barrier) and spraying chemicals are temporary measures. They can be used to stabilize sand surface and create a stable ecological environment for the establishment of artificial vegetation or for the rehabilitation of natural vegetation on sand dunes and wind-eroded lands (Liu 1982a, b; Zhu et al. 1998). Vegetative method primarily includes the establishment of artificial vegetation or rehabilitation of natural vegetation; establishment of sand break forest belts to prevent shifting sand from encroaching on oases, traffic lines, towns and other facilities; establishment of protection forest net to prevent farmland from being eroded by wind and pasture from degradation; protection of natural vegetation to prevent fixed and semi-fixed sand dunes and sandy grassland from aeolian desertification. What should be pointed out is that the type of protection system in sandy region of China was transformed from traditional ecotype to eco-economic type. Namely, in the processes of shifting sand stabilization and aeolian desertification control in a large area, timber forest, economic forest and fuel forest should be constructed appropriately, reconstruction of vegetation in pastures, rational utilization of artificial vegetation, enlargement of present oases and capital farmland and development of agriculture, forestry,

212

T. Wang et al.

Fig. 15.6 Spatial distributions of aeolian desertified land in northern China in 1950s, 1987, and 2000. Due to restoration policy, the desertification was reversed in some areas in the Northern China by the

end of 1990s. Human activities have also pushed the agro-pastoral boundary northwards by approximately 200 km from 1950s to 2000

stockbreeding, fishery and other industries to improve the living standard of people in sandy region (Zhu et al. 1989). Vegetative method to combat sand has the following six major advantages.

on biogeographic zone, so different sand-binding plants are chosen in light of local conditions all over the world. At the same time, the choice of sand-binding plants and afforestation tree species is also limited by local ecological conditions. What’s more, the success of vegetative method or not depends on how much wind erosion on sand surface can be controlled.

(1) The artificial, artificial-natural and natural vegetation on mobile and semi-fixed sand dunes can prevent sand dunes and sandy land from wind erosion and make them fixed permanently by covering sand surface and reducing wind velocity. (2) The constructed vegetation can improve the properties of barren shifting sand land and promote the formation of sandy soil. (3) The constructed vegetation can ameliorate the ecological conditions above and under the covered area, which is good for living organisms’ reproduction. (4) The constructed vegetation can propagate and regenerate by itself, even short life-span pioneer plant constructed on mobile sand dunes can evolve into stable ecological system with abundant plant species through automatic adjustment. (5) The combined arbor-shrub-subshrub-forage vegetation can not only afford appropriate grazing but also supply firewoods and timber. (6) Sand dune is a complicated system, including sand dunes, interdune area, flat interdune bottomland (meadow) and sandy flat. Once vegetation controlled the advancement of shifting sand and wind erosion, farmlands, orchards, melon land and forage bases even new villages can be established on fertile lands protected by vegetation. Obviously, vegetal sand stabilization is by no means an easy job. The choice of sand-binding plant species depends

15.6.2 Mechanical Method 1. Checkerboard Sand Barriers In the practice of sand control, mechanic measures are generally taken to fix a large area of shifting sand, and different standard grids or rows of sand barriers made of all kinds of materials (such as straw, reed, clay, and gravel) were extensively adopted. In general, several rows of sand barrier are adopted where prevailing wind direction is single and checkerboard sand barrier are taken where prevailing wind has multi-direction. Sand barrier is basic protection measure to control wind-sand harms. It alters the properties of underlying surface and increases the roughness of ground surface. When sand flows over straw checkerboard sand barriers, eddy and sand deposition take place. After long term of wind erosion and deposition, stable and smooth concave curved surface comes into being, with an average ratio of maximum depth to sand barrier’s border length of 1 : 10 or so. Regular wavy underlying surface composed of this kind of stable curved surface can produce an uplifting force, which ensures that surficial sand can’t be blown away and sand blown from other place can pass. Because this kind of underlying surface has an “uplifting effect”, it can uplift sand from other places.

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Aeolian Desertification Status and Its Control in China

Checkerboard sand barrier is characterized by increasing surficial roughness, decreasing the velocity of near surface airflow, thereby decreasing airflow’s capacity of transporting sand and changing the distribution of transportation rate at different height. Checkerboard sand barrier is effective where prevailing wind has multi-direction. When checkerboard sand barrier is built, upright sand barrier is also constructed at the windward side to prevent sand from sand depositing in front of sand-fixation belt and make sand-fixation belt much more efficient. The 1 : 10 ratio of checkerboard sand barrier’s height to width is best. The general standard of checkerboard sand barrier is 1 m
1 m, it is cheap and effective. Plastic net made into larger 2 m
2 m or 3 m 3 m checkerboard sand barriers in Algeria were also effective. Flexible materials are better than rigid ones. Someone proved sand barriers made of rigid concrete bars have bad effect on blocking wind and could cause wind erosion easily. Stripe sand barriers are effective where prevailing wind has single direction and sand barriers should be installed vertical to prevailing wind direction. High crop’s stubble left in farmland is an effective measure to prevent sand hazard in farmland near desert. Vegetative method combined with chemical measures to fix sand are the most effective way in industrial and mining areas or along road lines where sand hazard is very severe. 2. Upright Sand Fences Sand-fixing measures have very obvious protective effect, but sand deposited in front of sand fence often makes a large area of sand-fixing belts lose their function. As a result, it can result in the formation of new passage of sand flow and the occurrence of new sand hazard. So, sand-fixing measures should be combined with sand-blocking measures. Upright sand fences are built at the upwind frontal edges to block sand source and promote the formation of high sand-blocking dike which can prevent sand from depositing at the upwind frontal edges and change the transporting capacity of airflow. But it only can be built at the upwind edges, above 2/3 heights of windward slope and beneath the crest line, and should be set vertical to the prevailing wind direction (Zhu et al. 1998). Its effectiveness has several influencing factors. (1) Height. The heights of sand fences are determined by local transportation rate. If it is too low, it will be buried by sand soon. So, sand fences should be rebuilt frequently, it’s expensive and not convenient. But if it’s too high, it’s very difficult to be fixed. In general, 1 m is a suitable height. (2) Porosity. Indoor and field experiments proved the porosity of sand fences is the most important factor

213

influencing its protective effect. The protective effect includes: ① Sand-trapping capacity; ② Effective protection distance. For dense fence with a porosity of zero, it also can block sand, but its protective range in front of and behind the fence is shorter than its height. With the increase in porosity, the protective range and effect also increase. When the porosity is 30–40%, the protective effect is optimal. (3) Relationship between sand source, wind regime, possible transportation rate and fence location. Sand source, wind velocity and duration determine the sand transport rate. Sand transport rate determines the choice of fence. Fence location should be high and can’t be eroded by wind. To prevent the erosion of fence base, 2–4 rows of checkerboard sand fences are built at the windward base. In order to assess the protective effect of sand fences, we define the ratio (K, %) of fence’s sand-trapping quantity (Q0) per unit width (m) to the corresponding possible maximum sand transport rate (Qp) per unit width, namely K = Q0/Qp 100%, as the sand-trapping efficiency of sand fences, which is closely related to fence height, porosity, strike and fence location. What should be pointed out is that sand-trapping efficiency of sand fences is variable and it decreases with the increase of deposited sand volume. Because sand flow is blocked, sand flow direction becomes parallel to the sand mound strike. In fact, multi-directional wind also influences sand-trapping efficiency directly. For example, the average K value is 70–80% in Shapotou area, with the maximum value of 96.5%, and the protective range is 7.5–11.3 times the height of the fence. The application and constitution of sand fences are local-condition dependent. (1) Sand fences are effective in shifting sand area where prevailing wind direction is single. If combined with sand-fixing measures, the protection system “laying emphasis on fixation in combination with block” can prevent sand hazard effectively. For coarse flat sandy land or gravel land, single sand fences can be used, but they should be built on the windward side at a long distance from the protected target. If necessary, sand-blocking system of multilevel sand fences can be adopted. (2) Upright sand fences have been widely used to block sand and snow abroad. For example, to control snow on roads, the former USSR and America set a slot at the bottom of barriers which makes airflow accelerate and blow away snow on road and deposit at the leeward roadside. So, sand can deposit constantly and much sand accumulation can result in new hazard; the cost is

214

T. Wang et al.

expensive. In the sand-preventing experiments along the Nanjiang Railway and snow-preventing experiments along the Tian Shan Road in China, the “Feathered Transporting Sand (Snow) Measure” was adopted. It divides fences into many little segments, and the single fence is parallelly arranged according to certain trend spacing. It’s characterized by utilizing energy conversion function to change the direction of sand flow, accelerate wind velocity and blow sand away, with a transportation rate of 65–90% Of course, there is also an other sand-transporting measure, which can divert sand flow. For example, the section of road in desert can be designed as streamline form, or 1 : 8 gentle slope, which can enhance sand transport capacity, and therefore no sand deposition takes place near the road shoulder. Gravel platform along both side of railway in desert area has double protection function, firstly, gravel layer can fix shifting sand; secondly it has a strong rebound function for sand particles and has a non-accumulated transport function for the passing sand flow. The above-mentioned four kinds of sand control measures are also known as “fixation, block, transport and diversion” measures. Theoretic analysis and practices proved that sand-fixing measure is the most practical and effective measure to prevent sand damages. Because this measure can dissipate wind energy, sand-blocking measure is a necessary measure that ensures sand-fixing measure can play its role completely. Under special condition, the sand-fixing measure also can be used alone with obvious result. Practices also showed that different measures should be taken in the light of local conditions. What’s more, different measures should be appropriately combined because no single measure is perfect.

15.6.3 Chemical Method In 1930s, oil-prospecting workers in desert sprayed crude oil on sand dunes surface to prevent blown sand hazard and protect oil equipments. From then on, the concept of chemical dune stabilization came into being which brought a new and active research field. Enlightened by dune stabilization using crude oil, people did much work for developing new sand-fixing materials. As a result, a series of sand-fixing materials, organic or inorganic stabilizers were used. Up till now, chemical dune stabilization has a history of 70 years, but it developed rapidly and has become one of the important sand-fixing measures in arid regions threatened by blown sand damages, especially in desert zone with abundant oil source. Chemical dune stabilization can be divided into the following forms:

(1) Covering sand surface. Asphalt petroleum products or latex sprayed on sand surface, mostly due to strong absorption and electrical function of sand particles, and therefore they can only form a thin and weak protective layer. (2) Binding function. Almost all chemical sand-fixing material has such property, after chemical sand-fixing liquid occupy interspaces between sand particles, the action between particles can be increased and hence they form a bonding layer. (3) Hydration. For instance, action between concrete and sand particles can form strong and hard bonding layer. (4) Sedimentation function. When water glass and intensifier are used as sand-fixing materials, it infiltrates and occupies interspaces between sand particles, and the intensifier deposits and forms a strong and hard protective structure. (5) Polymerization. As polymer and latex are used to control sand, they can form elastic or rigid bonding structure. The principles of chemical dune stabilization are complicated; it’s not only related to the properties (such as chemical composition and mechanical composition) of sand particles, but also related to the chemical and physical properties (such as molecular structure, absorbability, and viscosity) of chemical sand-fixing materials.

15.6.4 Combination of Different Measures Construction and arrangement of protective system are determined by the characteristics of flow field and way or intensity of sand movement. Common arrangement schemes are as follows: 1. Protective system dominated by “fixation” and combined with “block” and “transport” and “diversion” It is a sand control measure and scheme suitable for controlling large area of shifting sand. It’s not only effective and practical but also accords with the principles of aeolian sand physics in theory. Speaking concretely, sand-blocking belts at the front edge can control sand source effectively; sand-fixing belts can stabilize sand surface, change the property of underlying surface and control the condition of sand movement efficiently, or create the condition for vegetative sand stabilization. If local natural conditions are better, plants can be used as fences, which are called “living sand barrier”. The length of this protective system should be set determined in accordance with the protected targets (such as railway or road). The width of protective system (protection width) is entirely determined by the migration speed of local mobile sand dunes, or by local possible maximum resultant

15

Aeolian Desertification Status and Its Control in China

transportation rate and direction. According to experiences in Shapotou region situated at the southeastern rim of the Tengger Desert, the effective protection width is 130 m at northern side of railway. We think even in extremely arid region, the protective width of 150–200 m is enough when the migration speed of mobile sand dunes is less than 1 m/a (SSDER 1980). 2. Protective system dominated by “block” and combined with “transport” It’s applicable to coarse flat sand land and gravel land. There may be two cases: first, sand source is far and not abundant; second, sand source is near, but its distribution is not even such as low barchan dunes areas at the edge of desert and interdune flat in the hinterland of desert. The common characters of these areas are flat and open in topography; wind is strong, sand source is limited and coarse. In the movement processes of sand, once it encounters obstacles such as roadbed, vegetation, etc., shifting sand will deposit and can result in sand damage. So, sand-blocking belts need to be built on windward side far from protected target. Because no protective measures are taken between sand-blocking belts and protected target, small amount of sand material may be conveyed and deposited near the protective system and lead to slight sand damage. Sand-transporting and sand-passing measures can be taken to resolve this kind of sand damage. In practice, single protection measure is also adopted; for instance, clay or gravel is used to completely cover the surface of sand dunes. The objective of land aeolian desertification control is to rehabilitate the degraded ecosystem, and build an artificial eco-economic system, which can ensure the sustainable development of ecological environment, natural resources and socioeconomic growth.

15.7

Rehabilitation Patterns of Aeolian Desertification Lands in China

Based on the status of aeolian desertification, aiming at the problems in aeolian desertification control, and to follow the principle of integration of ecological, economical and social benefits, we have generalized the rehabilitation patterns in semi-arid and arid regions from experiences of more than 50 years in aeolian desertification control in China (Zhu et al. 1989; Zhu 1992).

15.7.1 Rehabilitation Pattern in Semi-Arid Region Firstly, the occurrence of aeolian desertification is influenced by fragile environment, but in the semi-arid region, aeolian

215

desertification process will cease and can be spontaneously restored once intensive human disturbance is removed. In other words, semi-arid zone has ecological resilience. The grazing exclusion method is generally adopted in semi-arid region (Table 15.12). Even in slightly desertified area, it’s also an effective way. For example, slightly desertified land around Chaohaimiao of Horqin Zuoyi Houqi in eastern Horqin Sandy Land gradually recovered by itself with increased vegetation cover and biomass (Table 15.13) after 3 years of enclosure without other artificial measures. Secondly, it is a good measure to readjust the existing land use pattern that is not in conformity with ecological principles. That is to say, to change the farming management which is characterized by extensive cultivation and poor harvest and takes grains as the principal, and to enlarge the proportion of forestry and grazing to make them beneficial to both ecology and economy. The main points for readjusting the farming structure are to cut down the area of farmland which is influenced by aeolian desertification and intensive farming on the beach flats of lake basins and on the river valley plains where the water condition is better. The efficacy of readjusting the desertified lands in some typical regions show the problem clearly, Huanghua Tala Commune of Naiman Qi, Inner Mongolia, for example, was sandy grassland with an annual precipitation of about 360 mm. The areas of the desertified lands develop to occupy 81% of the total land area due to over-reclamation and over-cutting. Since the 1970s, the land used for dry farming has been readjusted. Consequently the proportion of forest and forage has been enlarged; the measures such as combination of tree, shrubs and grass, and planting tree belts and woodlots have been adopted. At present, the proportion of agriculture, forestry and grazing lands have been readjusted to 21 : 52 : 27. The desertified lands have been preliminarily controlled, the total grain output has been increased by 3.36 times, and the aeolian desertification process has been brought under control basically. The readjustment of land use structure centered on dry farming in Sijinzi Village of Tongyu County in western Jilin Province represents a successful example to control aeolian desertification. Sijinzi Village is located in the northwest of the county city where aeolian desertification was developing and aeolian desertification land accounts for 34.9% of the total area with an annual precipitation of 407.2 mm. Owing to over-reclamation of grassland, natural vegetation has been destroyed and the forestry and grazing lands were replaced by agriculture lands. As a result, the proportion of agriculture, forestry and grazing lands was changed from 2 : 1.5 : 6.5 in the late 1950s to 4 : 1 : 5 in 1970s. In the late 1970s, land use pattern centered on dry farming has been changed, and the proportion of agriculture, forestry and grazing lands was adjusted to 1 : 1 : 3. In 1984, it has been readjusted to 1.5 : 2.5 : 6, vegetation cover increased from

216 Table 15.12 Effect of enclosure on desertification land

Table 15.13 Changes of vegetation cover and biomass after enclosure around Chaohaimiao of Horqin Zuoyi

T. Wang et al. Location

Status before enclosure

Period

Vegetation coverage after enclosure/%

All Horqin

Shifting sands

1975– 1981

70–80

Around Duolun

Abandoned cropland

1968– 1981

60

Xi Ujimqin

Semi-fixed sandy lands with shifting sands in spots

1976– 1981

65

Ulan Odu of Onugiud Qi

Degraded sandy grassland

1972– 1981

80–90

Plant speices

Without enclosure

1 year enclosure

2 year enclosure

3 year enclosure

Coverage/ %

Output/ (g/m2)

Coverage/ %

Output/ (g/m2)

Coverage/ %

Output/ (g/m2)

Coverage/ %

Output/ (g/m2)

A. frigida Willd

30

130

45

228

50

255

65

271

A. halodendron Turcz. ex Bess

30

483

40

642

45

755

45

733

Stechm forbs

45

219

55

310

60

321

70

386

Bothriochloa ischaemum Keng

35

183

40

304

60

392

65

364

6.8 to 16.3%. Therefore, ecological environment was ameliorated and shifting sands were controlled. After the construction of field protective forest, the intensity of wind erosion decreased. As a result, per livestock share of forage was increased from 1850 to 3000 kg; the cultivated area decreased by 58.33%, but gross yield increased by 1.4% because of the increased per unit output. Peasants in this village changed their single agriculture cultivation to mixing farming, so per capita income increased from 177 RMB yuan to 500 RMB yuan, the economy of this village was greatly promoted. At the same time, aeolian desertification land has been reversed; both ecological and economic benefits were gained. The same successful examples can be seen in Mangkeng Village of Yulin County in Mau Us Sandy Land. According to research work of land use structure in typical areas, the optimal proportion of land use is different desertified aeolian areas (Table 15.14). It’s partly due to different aeolian desertification degrees and landscape. The more severe the aeolian desertification is, the more complicated the landscape structure is, and the higher the proportion of forest and grass should be. The adjustment of land use structure should be combined with the construction of capital farmland and enlarging the proportion of forestry and grazing land can gain ecological and economic benefits.

Take Baiyin Tala of Eleshun in Hure Qi of southern Horqin sandy land as an example, there was desertified area with mobile sand dunes and interdune area in the past. After adopting the measures to combat aeolian desertification, each farmer had 0.33 ha farmland, 0.5 ha woodlands and 6 heads of livestocks, with an annual income of about 300 RMB yuan, what’s more, 82% of aeolian desertification land has been controlled. Thirdly, the proportion of forestry and grazing land should be increased; in addition, the system of shelter feeding or half shelter feeding should be popularized. It is necessary to establish proper artificial grassland and forage farm to supplement the insufficient forage supply on the natural grazing fields. Owing to the combination of livestock breeding and farmland, both straw and green manure can be use as supplemental forage. It possesses very important significance to the development of livestock and also possesses evident function to the increment of economic efficacy. In the counties of the sand areas in Yulin Prefecture, for example, the value created by per labor engaged in livestock breeding is 1.38 times more that that created by each man power engaged in agriculture. Fourthly, another measure is to recover the natural vegetation on the desertified lands without productive potential. The exclusion of grazing animals should be emphasized.

15

Aeolian Desertification Status and Its Control in China

Table 15.14 The optimal proportion of land use in different desertified areas

217

Characteristics of desertification land The developing aeolian desertification land with slight wind erosion and sand deposition

Proportion of land use/% Farming

Forestry

Grazing

61

20

19

The developing aeolian desertification land with coarsening surface

47

27

26

The developing aeolian desertification land with coppice dunes

29

30

41

Intensively developed aeolian desertification land with shifting sands and fixed, semi-fixed dunes

15

30

55

Severely developed aeolian desertification land with beach flat of lake basins and mobile sandy dunes

10

40

50

Afforestation should be practiced on sand dunes. Shrub or grass should be planted in depressions. The fixation of shifting sands on the both sides of railway near Naiman of Horqin sandy land, Dayijianfang of Zhanggutai and Hongshixia of Yulin in Mau Us Sandy Land are successful examples. There is severely desertified land with numerous mobile sand dunes along the Naiman section of Jing-Tong Railway. Plant was planted to fix mobile sand dunes, and engineering measures were also adopted. The protection system consists of arbor (mainly P. silvestris L. var. mongolica Litv), shrub (mainly A. halodendron Turcz. ex Bess, S. gordejevii Chang et Skv. and C. microphylla Lam), tame grassland and enclosed natural vegetation, which prevent the development of shifting sands and ensure smooth operation of the railway. As a result, the vegetation cover increased from less than 10% before treatment to present 30–50% and the velocity of sand flow decreased by 60–70%; the content of surficial organic matters also increased and was 6–8 times that of shifting sands; the content of fine particles less than 0.01 mm increased by 2–4 times. The severely desertified land began to reverse. Table 15.15 is an example of environmental changes after aeolian desertification land has been controlled. The farmland protective networks should be established in the beach flats. Also the tree networks should be planted on the alluvial plains of rivers to prevent the basic farmland from being damaged by wind and sand. The Yuxi River Basin in Yunlin County in southern Mau Us Sandy Land is a typical example. In one word, the land use structure with grazing, forestry and agriculture integrated organically should be established in semi-arid region in light of local conditions, namely it’s the integrated structure of commercial stockbreeding, protective forestry and self-sufficient agriculture (Dong and Gao 1993; Zhu 1999a). This structure should be centered on beach flats and river valley plains. Aeolian desertification land in agro-pastoral ecotone will be controlled step by step only if above mentioned artificial ecological system is established.

The above measures can be generalized as a rehabilitation pattern showing in Fig. 15.7. Besides determining reasonable carrying capacity, popularizing reasonable rotational-grazing and establishment of tame grassland and forage base, aeolian desertification land control in grazing area of semi-arid region still requires appropriate allocation of wells’ density and the construction of road.

15.7.2 Rehabilitation Pattern in Arid Region The development of aeolian desertification in arid region, on one hand, is attributable to the irrational utilization of water resource in the downstream basin, on the other hand, is due to the destruction of vegetation at the margin of oases which leads to the activation and advancement of sand dunes. So, measures should be taken as follows: (1) Taking the inland river basin as an ecological unit to make an overall plan. In accordance with the principles of overall consideration of all factors in the upper, middle and lower reaches of rivers, it’s important to unify the management and utilization of surface and underground water resources, to allocate reasonably the water supply along the river, to implement the regulation of regional general layout and the structure of irrigated oases which rely on water supply, and to establish stable and high efficient artificial ecosystem in the river valley. So, it’s necessary to adjust the degree of land use and exploitation in accordant to the maximum irrigating capacity, namely to determine the area of farmland according to the volume of water resources. (2) Center around the irrigated oases, sand blocking belts of grasses (using the surplus water in winter season) should be set at the outskirts of oases, sand breaking forest consisting of trees and shrubs at the margin of oases, and farmland protective networks and windbreaks in the interior of oases, such as patterns in Turpan, and Hotan Oasis.

218 Table 15.15 Environmental changes after aeolian desertification land management (Sanjiazi of Zhangwu)

T. Wang et al. Phase

Percentage of different landscape/% Flake of shifting sand

Land slightly eroded by wind

Speckled shifting sand

Slightly decertified land

Before

44

25

9

22

After

8

4

6

82

Fig. 15.7 Rehabilitation pattern of aeolian desertification land in agro-pastoral ecotone of semi-arid region

(3) For shifting dunes around the edge of oases, sand barriers should be planted on shifting dunes and sand binder vegetation should be planted inside, also sand barriers and shrubs should be established in the interdune areas to create a comprehensive protective system, as the Pingchuan pattern in northern Linze Oasis in the Gansu province. At the same time, measures should be taken to protect natural forest and shrub clumps in the marginal area of oases and in desert.

During the rehabilitation process of aeolian desertification land in arid region, efforts should be made to change badland into cases that there are good water and soil conditions in the marginal area of desert and on inland river banks, perfect construction of irrigation works, effective farmland protective networks and soil melioration measures. Some typical examples are exhibited in Shihezi-Kuitun area at the southwestern edge of Gurbantunggut Desert and some oases in middle reaches of the Tarim River at northern edge of Taklimakan Desert.

15

Aeolian Desertification Status and Its Control in China

Table 15.16 Landscapes changes around oases after aeolian desertification land management (Pingchuan sand control station in Linze)

219

Landscape

Area percent/% Before

After

Intensively developing aeolian desertification land

17.8

0.4

Shifting sand dunes

54.6

9.4

Reversed aeolian desertification land

9.0

52.4

Insusceptible farmland

8.9

37.8

Badland

9.7

Fig. 15.8 Main techniques to control aeolian desertification

The shifting sand fixation and available land resources exploitation around oases, and the construction of new oases in arid region are essentially the combination of reconstruction and exploitation of aeolian desertification lands, which are also the two basic aspects of aeolian desertification control. The integration and supplement of two aspects ensure the gain of ecological and economic benefits. The data in Table 15.16 show the changes of landscapes around oases before and after combating aeolian desertification. On one hand, it indicated the decrease of severe aeolian desertification land and intensively developing aeolian desertification land; on the other hand, it shows that part of aeolian

desertification land has been changed into woodland and orchard, the productivity of degraded land has recovered and aeolian desertification began to reverse. For the areas encroached by mobile sand dunes in arid region, measures to fix shifting sands should be taken, especially in regions where roads pass through. According to local successful practices in the rehabilitation of aeolian desertification land and related experiments in the marginal area of desert in arid region, the measures to combat aeolian desertification land can be generalized into the patterns showing in Fig. 15.8.

220

15.8

T. Wang et al.

Summary

Land aeolian desertification is not only an important ecological problem, but also a very critical economic and social problem, which hampers the sustainable development of Chinese economy and society. Although significant achievements have been made in aeolian desertification control, yet only a small proportion of the desertified land has been improved, and in most regions the situation has become worse. We think that an urgent need is to review why long-term efforts have so far only achieved less major results, and where the crux of the problem lies. Today, the most urgent task for aeolian desertification control is the innovation of aeolian desertification control models and institutions. The target of land aeolian desertification control is to rehabilitate the degraded ecosystem, and build an artificial eco-economic system, which can ensure the sustainable development of ecological environment, natural resources and socioeconomic growth.

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State Environmental Protection Administration of China (SEPA) (1999) Reports on ecological issues in China. China Environmental Science Press, Beijing Team of “Researches on Desertification (Land Degradation) Control in China” Project (TRDCCP) (1998) Researches on desertification (land degradation) control in China. China Environmental Science Press, Beijing Wang T, Wu W, Wang XZ (1998) Remote sensing monitoring and assessing sandy desertification: an example from the sandy desertification region of northern China. Quat Sci 2:108–118 Wang T, Wu W, Xue X (2004) Temporal and spatial changes of desertified land in Northern China in the past 50 years. Acta Geogr Sinica 59:203–212 Wang XZ, Wang T, Xu JY (1994) A geographic system on monitoring and assessing desert disasters. In: He JB, et al (eds) Research progress on remote sensing monitoring and assessment for great natural disasters. China Science and Technology Press, Beijing Wang T, Wang XZ, Wu W (1995) Disaster zoning of desertification in China. In: Wang JF (ed) Natural disasters zoning: disaster zoning, assessing influences and countermeasures of reducing disasters. China Science and Technology Press, Beijing Wang T, Wu W, Xue X (2004b) Study of spatial distribution of sandy desertification in North China in recent years. Sci China Ser D 47:78–88 Wang T (1992) A preliminary study on development trend of sandy desertification in Northern China. In: China Association for Science and Technology. First symposium of young scholars (cross-discipline). China Science and Technology Press, Beijing Wu W (1997) Remote sensing monitoring methods of desertification dynamics and practice. Remote Sens Tech Appl 12(4):73–89 Wu W, Wang XZ, Yao FF (1997) Applying remote sensing data for desertification monitoring in the Mu Us Sandy Land. J Desert Res 17(4):415–420 Wu W (1991) Visual interpretation of TM images applying for investigation of resources. In Wang YM (ed) Symposium on remote sensing application in renewable resources. Science Press, Beijing Zhou XJ (1989) Sandy desertification in Tarim basin in historical period. Arid Zone Res 1:9–17 Zhu ZD, Chen GT (1994) Aeolian desertification in China. Science Press, Beijing Zhu ZD, Liu S (1981) Process of sandy desertification and control in North China. China Forestry Publishing House, Beijing Zhu ZD, Liu S, Di XM (1989) Aeolian desertification and control in China. Science Press, Beijing Zhu ZD, Zhao XL, Ling YQ (1998) Sandy land rehabilitation engineering. Science Press, Beijing Zhu ZD (1992) The trend of aeolian desertification land in China and basic sand control pattern. China Sci Fund (1) Zhu ZD (1999a) Measures to control sandy desertification in the interlaced zone of farmlands and pasture-lands in north China. In: Zhu ZD, et al (eds) Sand desert, sandy desertification, desertification and control in China. China Environmental Science Press, Beijing Zhu ZD (1999b) Spatial distribution of land desertification in China. In: Zhu ZD, et al (esd) Sand desert, sandy desertification, desertification and control in China. China Environmental Science Press, Beijing

The Landslide/Debris Flow and Control Technology in China

16

Peng Cui

16.1

Distribution Law and Characters of Landslide/Debris Flow in China

16.1.1 Mountain Hazards in China China is a country of 6.66 million km2 mountainous area (including plateaus and hills), accounting for 69.4% of the total state’s land areas, and the mountainous population accounts for more than one-third of the entire population. With uplifting of the Qinghai-Tibet Plateau and monsoon climate, China owns the complex geological structure, steep slope and high relative altitude, and concentrated precipitation. Unique gravitational potential energy gradient of mountainous regions and abundant precipitation make landslides and debris flows (L/DF for short) frequent in a wider area and cause serious damages. According to statistics (Cui 2015), thousands of hazards occur every year and 74 million people are endangered at different levels. From 2001 to 2010, 9933 people were killed or missing due to sudden landslides or debris flows (excluding about 25,000 people killed by landslides, rock falls and debris flows during the 2008 Wenchuan earthquake) with about 1000 people killed or missing and a staggering loss of 114 billion yuan each year on average. On August 8, 2010, a single event that included debris flow and flood in Zhouqu County of Gansu Province caused 1765 people dead or missing, 4321 houses destroyed making 22,667 people homeless. In July 2014, a wide range of strong precipitation occurred in western Sichuan, which caused group-occurring landslides, debris flows and mountain floods in 10 counties and cities. 269 towns and 118 million people were affected and the direct economic loss was more than 114 billion yuan. Similarly, 166 people were dead or missing because of the landslide occurrence in Wulipo of Dujiangyan City. P. Cui (&) Institute of Mountain Hazards and Environment, CAS, No. 9, Block 4, South Renmin Road, Chengdu, 610041, P. R. China e-mail: [email protected]

The construction facilities, traffic arteries, hydropower projects, farmland, forests and the life of residents have been seriously threatened and destroyed by landslides and debris flows through the process of scouring and silting. The huge casualties, economic losses and ecological damages have seriously restricted the development and sustainable development of mountain resources. What’s more, the risk of the mountain disaster will exacerbate the economic downturn in these mountainous areas with rich natural resources (Chen and Wang 2004).

16.1.2 Distribution of Landslides and Debris Flows The distribution of landslides and debris flow is dominated by a variety of controlling factors, which could be grouped into geology, landform, hydrology, climate, vegetation and human activities. In general, seismically active areas and fault developed belts where feature active neotectonic movement, high crustal uplift rates, high relief, climate conditions of intense rainfall and frequent rainstorm are more sensitive to landslides and debris flow. Moreover, the elevated temperature of the alpine area and climate change-induced frequent extreme weather events could also intensify landslides and debris flow activity. Basically, the primary controlling factors of triggering landslides and debris flow are topography with stratigraphic sequence, lithology and geological structure with favourable material conditions; climate and extreme weather events act as key external factors. Combined, these three factors cause the largest number of landslides and debris flow. Investigation so far shows the distribution of landslides and debris flow in China with the control of aforesaid three major factors has the following rules. 1. Geomorphologic factors on the distribution of landslides and debris flow.

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(1) Landform dominates distribution and development

(2) Band-shaped distribution in deep gorges

Overall, the distribution of landslide and debris flow in China is most affected by the landscape pattern. China’s physical terrain has been divided into three individual geomorphic terraces, respectively, made up of plateau (first terrace), hills (second terrace) and plains (third terrace), from west to east, and the transition belts between terraces cause the highest density of landslide and debris flow. To the east of the line represented by the Da HingganTaihang-Wushan-Xuefeng mountain ranges, the low-relief terrain, mainly hill and plain, makes poor gestation conditions for landslide, avalanche and debris flow which are sparsely distributed. To the west of this demarcation line are the areas dominated by a landscape of extensive plateau, deeply cutting very high-relief mountains, high-relief mountains and median-relief mountains where landslides and debris flow are heavily distributed in a band-shape or sheet-shape. The transition belts between first and second terrace as well as second and third terrace develop landforms of high relief, steep slopes and deeply cutting valleys, making these areas most susceptive to landslide and debris flow. The transition belt between first and second terrace includes conjunction regions of the northeastern Qinghai-Tibet Plateau and the Loess Plateau, eastern China and Yunnan-Guizhou Plateau (Hengduan Mountains area), whose northern part lies in the upper reach of the Yellow River, and the southern one is in Lancang, Nujiang, and Jinsha rivers drainage basins. This area has steep mountains and deep river valleys generally ranging from 3000 to 5000 m above sea level with a relative elevation greater than 1000 m, developing multi-level planation surfaces and highly-located well-developed river terraces, provides advantageous natural conditions of material source and landscape for triggering large-scale landslides and debris flow (Fig. 16.1). Bailong River, the upper reach of Minjiang River, Dadu River, Anning River and down the reach of Jinsha River have been referred to as high-occurrence disaster zone for landslide and debris flow. The transition belt between second and third terrace includes to the south of Qinling Mountains, Daba, Wushan, Xuefeng, Wulin mountains, and so on, generally ranging from 1000 to 2000 m above sea level with relative elevation greater than 500– 1000 m, which also develops multi-level planation surfaces and extensive fluvial terraces with convex outline and low surface angle. This is a typical geomorphological combination for large scale landslide forming. Lying in this region, the Three Geoges Reservoir faces is prone to landslides and avalanches; as around 5000 had already occurred such as Jipazi landslide in 1982 and Xintan landslide in 1985, both having a material volume of 2
107–3
107 m3 and the phenomena is still continuing.

The steep slopes, the action of the geological structure, frost weathering, plenty of joint fissures in the bedrock by earthquakes and erosion, provide a huge amount of loose material and also destabilize the mountains, which favors the occurring of the landslide and debris flow, and consequently cause landslide or debris flow-dammed lakes. The slope angle of the middle and lower parts of the hillslopes along the valley banks are mostly between 21° and 35°, which is the optimal slope angle for the formation and occurrence of landslides. Because of the high hillslope angle (>60°) of a considerable part of the deep cutting valley, the occurrence of avalanches is common in this geomorphological unit. Besides, ravine areas resulting from the crustal uplift, also frequently hit by a strong local rainstorm. Sichuan-Tibet Highway traverses the famous Hengduan Mountains range, suffers from serious geological disastrous attacks in this alpine section. Landslide and debris flow have become the major factors affecting the traffic. (3) Vertical differentiation of distribution The terrain of China features “high-east and low-east”, covering a very wide span of altitude. The western plateau blocks the westward migration of warm and humid air currents, and corresponding rainfall is high in the southeast, and less in northwestern parts. Hazards inducing factors, such as topographic relief, climate and hydrology conditions, and soil and vegetation types show zonal changes. As the altitude rises, debris flow activities present some regularities, and could be classified into five types: rainstorm-induced debris flow in at low altitudes (below 2100 m), ice-snow melting runoff-induced debris flow at altitudes nearby 2100– 3500 m, glacial debris flow (3500–4000 m), glacial lake outburst debris flow or flood (above 4000 m). Landslides occurred in alpine cold areas are strongly connected to the seasonal freezing and thawing activities and melted ice and snow runoff. At the same time, glacial lake outburst debris flow or flood frequently occur since this region has densely distributed glacial lakes. 2. The factor of lithology and geological structure on distribution of landslides and debris flows (1) Concentration in the soft lithological zone Alternated soft and a hard layered rock and soft rock zones are more vulnerable than lithological homogeneity of hard rocks, making them conducive to landslides and debris flow formation. Main lithological units easy to develop debris flow and landslides in China are as follows.

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Fig. 16.1 Steep variation area of eastern Tibetan Plateau

(1) Soft rock and loose deposit with poor consolidation in Cenozoic strata and clay have low mechanical strength, are easy to be damaged and eroded to develop debris flow and landslides, such as Xigeda stratum in Pan-Xi region and loess in northwest China. (2) Mesozoic continental strata have poor cementation degree, low shears strength is easy to soften. Its expansion and shrinkage effect is obvious when moisture changes and rock surface disintegrates rapidly, which often forms a thick layer of debris. The consolidation of gypsum-salt strata decreases on the effect of water. The sloped body is prone to be instable when dip direction is the same as slope aspect, as a result, landslides occur and provide loose material for debris flow. (3) An ancient metamorphic rock with dense joint and fracture often has thick weathering zone, especially sericite and chlorite are prone to weather into clay materials, and it easily results in landslides. For instance, some famous debris flows gullies such as Jiangjia Ravine of Dongchuan, Yunnan Province and Huoshao Ravine of Wudu, Gansu Province are located in metamorphic rock areas. Lithology not only affects the distribution of hazards but also determines the type and character of hazards. For example, typical soil landslide and debris flow develop in loess areas while viscous debris flow occurs in strong metamorphic belts. (2) Concentration along the active fault zone The existence of stress concentration around the fault zone makes the rock mass compress and crush strongly. With the deep river incisions, different scales of collapses and landslides occur which ultimately provide abundant loose material for debris flow formation. Therefore, landslides and debris flow concentrating along fault zone are closely relative to tectonic activity, a common phenomenon in the northeast Longmen mountain fault zone, northwest trending Yushu-Ganzi-Luhuo fault zone, and nearly south-north

Anninghe-Xiaojiang fault. Mountainous areas along the aforementioned fault zones concentrate abundant landslides and debris flows with the banded spatial pattern. These areas have the maximum number of the most active, and the worst hazards in China. One hundred and four disastrous debris flows, 76 large- scale landslides and collapses distribute along both sides of roads in Palongzangbu basin, among which the debris flow caused by an ice-lake break in Midui Gully, the glacial debris flow in Guxiang Ravine, the “102” landslides and the Layue landslide are extra- large scaled disasters. 3. Climate factors on distribution of landslides and debris flow (1) Climatic affects the distribution pattern The line of Da Hinggan Mountains ZhangjiakouYulin-Lanzhou-Changdu-Linzhi is an important climatic boundary in China. Most northwest regions of the boundary belong to the arid and semi-arid climate zones, with the annual rainfall of below 500 mm, and few mountain hazards (landslides, debris flows, floods, etc.). However, the humid and semi-humid climate zones (annual rainfall >1000 mm) mainly located in the southeast of this boundary has frequent densely distributed landslides and debris flows. In the Tibetan Plateau, the seasonal thawing environment is crucial to the occurrence of the temperature-related mountain hazards. The main types of these hazards including glacial debris flow, glacial lake outburst flood and freeze-thaw landslide usually occur in spring and summer. For example, in April 2000, a super-large landslide (3
108 m3) occurred along Zhamu Creek, southeast Tibet. And the resultant landslide dam blocked the Yigong River. The impoundment lasted for 62 days before a catastrophic breaching caused a massive outburst of flood in the Yarlung Zangbo (Tibet) and the Dihang rivers (India) that travelled downstream to the main floodplain of the Brahmaputra in

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northeastern India causing massive casualties (Shang et al. 2003; Delaney and Evans 2015). The monsoonal climate affects and controls the distribution pattern of mountain hazards in China. Affected by the monsoon, there is an uneven distribution of precipitation. Precipitation in some areas is extremely rich, which provides favourable conditions for the formation of more mountain hazards (landslides, debris flows, floods, etc.) than less rain receiving areas. The east and southeast, and the southwest of China are mainly affected by the Pacific as well as Indian Ocean monsoon respectively, which lead to abundant seasonal precipitation (>75% of the annual rainfall mainly concentrated in summer and autumn). This said climatic characteristic makes the mountain hazards present appear at the high frequencies and large scales in these areas. Due to the long transmission distance of the warm wet air from the ocean, the north and northwest of China are mainly controlled by the cold temperate continental air mass for a long time and receive less precipitation, a not so conducive situation for the formation of mountain hazards. The maximum precipitation hotspots in certain slope and height of the mountains, however, are contributing to the formation of landslides and debris flows. The summer rainstorm is an important triggering factor for most landslides and debris flows in these places. (2) Concentration in highly intense rainfall area Distribution of mountain hazards is closely related to the distribution of strong rainfall. In the past, more than 80% of the landslides and debris flows had occurred in the rainy season. Similarly, the density of debris flow had shown a positive correlation with the average annual precipitation, summer precipitation, 24 and 1-h maximum precipitation. It had also increased with the increase in the number of daily precipitation greater than 10 mm, 50 mm, 100 mm, 150 mm and 200 mm, respectively. In July 1981, a oncein-a-hundred-year rainstorm occurred in northwestern Sichuan, southern Shaanxi and southern Gansu, and more than 60 thousand landslides and 1000 debris flows were triggered showing a solid proof of the impact of heavy and/or continuous rainfall on densely distributed mountain hazards.

16.2

Formation Condition and Mechanism

16.2.1 Formation Condition of Hazards The formation of landslide and debris flow results from a combination of a certain form of material (including solid

and liquid materials), and energy (including the energy of both solid and liquid materials) condition. The disaster formation conditions can be understood from the contribution of various factors to material production and energy transformation, and it is analyzed by investigating basic and triggering situations. 1. Energy condition The energy condition mentioned here is the driving force of starting and movement of landslide and debris flow. The energy of landslide and debris flow formation mainly comes from the gravity of loose solid material, the hydrodynamic force of running water (including slope runoff, valley runoff, and river runoff), the hydrostatic and dynamic water pressure of underground percolation, and so on. The Mohr-Culomb criterion (that is, the driving force is greater than the initial static shear force) is commonly used to describe basic conditions of solid material starting. Differential weathering of rock mass in nature, lubrication of fissure water and groundwater runoff, and weight of the water can lead to an increase of self-weight of loose solid material, or the water fills the porously of loose solid material to reduce internal friction angle (u) and cohesion (C), so that the loose solid material starts moving downward by meeting the condition that the driving force of loose solid material is greater than its initial static shear force. Water is Newtonian fluid which can have automatic flow by converting its own potential energy into kinetic energy and has the eroding and transporting capacity of earth materials. Therefore, the gravity of loose solid material, the hydrodynamic force of surface runoff, the seepage force and hydrostatic pressure of underground percolation are all the manifestation of different types of forces in the earth’s gravitational field, and their values can be reflected by geomorphic conditions. For a river basin or a region, the greater its relative height, the greater the potential energy of loose solid material so as the kinetic energy of groundwater. The greater the hill or trench slope, the better the condition of converting potential energy into kinetic energy of loose solid material, and the faster the conversion rate, and the greater the kinetic energy of both surface water and groundwater. Usually, extremely high-relief mountains can provide enormous energy for landslide and debris flow formation whereas the energy provided by high-middle mountains, middle-low mountains, and low mountain-hilly regions decreases successively. The energy provided by high and steep slope is greater than that provided by gentle slope. In general, a hazard- formative body with larger energy when starting has a greater damaging capability.

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2. Material condition

3. Triggering factors

The material composition of landslide and debris flow includes three major categories: solid material (loose clastic material), liquid material (water), and gas material (air). The effect of air can be ignored since its low content has little effects on the properties.

Triggering factors refer to one or a group of environmental factors that directly lead to the starting of water and soil motion on the ground in a critical state (or a state of limit equilibrium for solid) to form landslides or debris flows. The formation of landslides and debris flows is the coupling result of hazard bodies in the limit equilibrium and the triggering factors (Cui et al. 2018). General triggering factors include water, dam-break flood, earthquake and human activities, etc.

(1) Solid material Solid material (rock and earth mass, solid water) is a main component of the hazard-formative body. The component of rock and earth mass forming landslide and debris flow is complicated. It includes weathered detritus, zonal soil after pedogenesis process, remains of animals and plants, and so on. The size can be from semi-weathered rock masses and massive stones (boulders) to lime (including colloidal particles). Among them, the fine particles (clay and colloidal particles) in soil have great influences on the nature of landslide and debris flow. Therefore, the loose solid material from weathering product of rock mass, rock mass itself, and soils are mainly considered while analyzing the solid materials that play a role in landslide and debris flow formation. Additionally, particle size composition of loose solid material determines the nature of the hazard-formative body, and it has different requirements for energy formation conditions. (2) Liquid material The liquid material is also a main component for the initiation of a landslide and debris flow, and it plays an important role in debris flow formation especially. The liquid material of landslide and debris flow is mainly liquid water, and its source can be divided into four categories: atmospheric precipitation, melting water, outburst water from dam embankment of reservoir, channel and lake, and groundwater. There are mainly melting water in the high and extremely high mountains, but atmospheric precipitation is the main source of water in other regions. The outburst water is also significant in the regions of dense reservoirs, channels, and natural lakes (including frozen and avalanche lake). Liquid material plays a different role in the formation of landslide and debris flow. For debris flow formation with fluid flow, liquid water is the component and driving force, and plays a decisive role; for landslide and collapse formation with block sport, liquid water increases self-weight and changes the stress condition mainly by reducing the internal friction angle and cohesion of geotechnical material.

(1) Water The water that can provide triggering conditions for the formation of landslides and debris flows inducing atmospheric precipitation, ice and snow meltwater, meltwater and atmospheric precipitation, groundwater, etc. Atmospheric precipitation can provide triggering conditions for the formation of a fluid hazard body. Heavy rainfalls produce surface runoffs directly and rapidly which converge into gullies to form mountain torrents. When the intensity of mountain torrents reaches a certain critical value, the fluid dynamic will be greater than the resistance of the solid particles on the slope, and the channel bottom deposit will be carried into the fluid. When the solid particles in the fluid reach a certain concentration, they will evolve into debris flows (Honda and Egashira 1997). Similarly, after the infiltration of atmospheric precipitation into slopes, the slope weight increases, while the internal friction angle and cohesive force reduce. When the sliding force is greater than the anti- sliding force, the collapses or landslides will occur. In the high-temperature period, the melting of glaciers, snow and frozen soil are accelerated to form runoffs inside and on the surface of the snow and ice. When meltwater constantly and/or massively mixes with valley water, the water flow of the channel increases and induces mountain torrents with the strong scouring of the channel bottom and further cutting down the river banks which carry the large mass of loose solid material into the fluid. When the fluid-solid materials reach a certain concentration, they will transform into debris flows. Therefore, the continuous and powerful mountain torrents formed by the meltwater of ice and snow are the triggering conditions for the formation of meltwater-induced debris flows. Under general conditions, it is hard for groundwater or confined water to trigger fluid-motion mountain hazards. However, the activity of groundwater in saturated soil conditions can provide favorable environment for the formation of collapses/landslides.

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(2) Dam-break flood Whether they are natural dams (natural lakes, natural barrier lakes, glacier lakes) or artificial dams (reservoir dams, diversion canal embankments, tailings dams), when the sum of static pressure, uplift pressure and wave impact forces in the dam are greater than bearing capacity, or in the case of water overflow, dams can go to different degrees of outburst (Huggel et al. 2002). Once the dams burst, a huge amount of water will behave as the liquid material of mountain hazards and a considerable amount of material from dams will also come as solid material. After the coupling of two substances: if the fluid density is less than 10.8 kN/m3, they form sediment-laden mountain torrent; if the fluid density is 10.8– 13.7 kN/m3, they form high-sediment mountain torrent; if the fluid density is greater than 13.7 kN/m3, debris flow would be formed. Mountain torrents and debris flows flow in the valleys, and further scour the ditch bottom and cut down the two sides of the slope foot. Consequently, slope landslides and collapses will be induced with strong soil and water loss. (3) Earthquakes Earthquake, especially strong earthquakes, can release huge kinetic energy. These massive kinetic energies and suitable environmental conditions can provide a conducive situation for the formation of landslides and collapses (Zhuang et al. 2010). When the seismic waves act on rock and soil, two situations could occur: the first situation is earthquakes induce landslides and collapses especially in areas that seismic load is far greater than the structure of rock mass strength; the second situation is no formation of collapses and landslide under the seismic loads, but slope rupture and damages can happen and form potential disasters. In addition, the loose solid material, which is saturated with water, is destroyed and liquefied by the severe vibration of earthquakes. (4) Human factors With the development of social infrastructure and economy, the relationship between human activities and nature is getting closer. The human activities do not comply with the laws of nature, such as the excessive exploitation of natural resources, and designing and constructing of various projects without digging into natural environmental settings, will lead to the alteration of natural ecosystems, and can be conducive to the formation of landslides and debris flows.

P. Cui

The artificial factors to trigger mountain hazards include slope cutting, load and load reduction, irrigation, drainage of domestic water, underground water (confined water) digging, etc. (5) Slope cutting When humans in the mountainous areas construct railways, highways, hydropower and water conservancy engineering infrastructures, slopes are excavated because of the space limitation with the development of cities/towns. The free surface of the hillside above the excavation site will increase, or a new free surface will be formed. The hillslope converts into dangerous slope because of loss of support in its lower part, and after a certain time of evolution, it develops into collapse or landslide. In addition, the slope surface of the bare rock soil formed by the cutting slope and the excavated soil slope also provide loose solid material for debris flows. (6) Changes on hillslope load Loading refers to the increased load in the middle and upper part of collapses or landslides, such as accumulation of rock and soil, and newly built houses. Loading will lead to increasing sliding force and triggering landslides, such as landslides in Guangming Village, Shenzhen (Ouyang et al. 2017). Loading reduction refers to reducing the load in the middle and lower part of collapses or landslides, such as excavation and remove the housing. Slope unloading will lead to reducing the anti-slide force of collapses and landslides with the ultimate inducing environment for slope failure. (7) Irrigation and domestic water The occurrence of landslides caused by irrigation and domestic water is common. Large and stable collapses and landslides tend to be flat with thick soil and good irrigation conditions, as good places to develop agriculture in different types of terraces. But irrigation water infiltrates into the landslide body, which increases the weight of slope mass and reduces the internal friction angle and cohesive force causing favorable ground for the occurrence of landslides (Jin and Dai 2007). Improper disposal of domestic water (including industrial water) of the villages and towns, industrial and mining enterprises which are built on a basically stable large landslide terrace can also become a trigger condition for such collapses.

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16.2.2 Formation Mechanism 1. Formation mechanism of landslide Landslide occurs frequently in China. In particular, catastrophic landslides are dominant. In Western China, the large-scale landslides are notable for their scale, complex formation mechanism and serious destruction, which are typical and representative in the world. The fundamental causes of large-scale landslide in China are the favorable geomorphological conditions and strong internal-external dynamic factors (such as earthquake and rainfall). About 80% of large-scale landslides were found in the first slope-descending zone of the mainland topography around the eastern margin of Tibetan Plateau. Moreover, this area is the most active area of the plate tectonic activities. The intensive interactions between the endogenic and epigenetic geological process cause a serious dynamic change of the high steep slope, which are resulted in the development of large-scale landslides. Strong earthquake, extreme weather conditions and the global climatic change are the main triggering factors of large-scale landslides. Detailed analyses of the cases show that the mechanisms of large-scale landslides in China are complex. The large-scale landslides can be summarized into three types: rock landslides, soil landslides and landslides in debris. The typical geomechanical models of large- scale landslides in rocks are shown as following: the “three sections model (i.e. sliding-tension cracking-shearing), “retaining wall collapse” model, “horizontal-pushing” model in horizontal strata, large- scale toppling model in anti-dip strata, and the creepbending-shearing model, etc. Each model corresponds to some specific rock structural conditions and deformation processes. (1) Three section-mechanism: sliding, tension cracking and shearing In the sliding/tension cracking/shearing mechanism, there are three deformation and failure stages: creeping along low inclined cataclinal structural planes, tension cracking in the rear, and shearing failure of the ‘‘locking section’’ in the middle. This resistant part, acting as a lock to restrict slope deformation, is crucial for slope stability (Fig. 16.2). The sliding/tension cracking/shearing mechanism typically occurs in slopes that consist of ① brittle rocks, or rock and soil, with near horizontal or gently inclined structural planes at the foot of slopes and ② hard rocks with thin interlayers of weaker material (Zhang and Liu 1990; Huang and Deng

Fig. 16.2 Creep-tension-shearing mechanism of a landslide (three section mechanism)

1993). Huang used a visco-elastic-plastic finite element method to investigate the sectional deformation (Huang et al. 1991). The conditions for creeping along the soft structural planes of the slope can be expressed as follows: K  Kc ¼ ð1 þ C  tan uf cot 2aÞ=ð1  C  tan uf cot 2aÞ ð16:1Þ where, K ¼ r1 =r3 ; a is the angle between normal to the structural plane and r1 ; uf is the long-term strength index, C ¼ tan uf = sin 2a. (2) “Retaining wall” collapse mechanism The whole slope shows a loose structure, but there are comparatively rigid geological bodies in the middle or front parts of the slope; the strength of the rigid part is very high, such that it acts as a “retaining wall”. The rigid part is usually pressurized by a strong force, caused by the deformation of the upper sliding mass. The function of the rigid part is the same as the “locking section”, which plays a critical role in maintaining the stability of slopes. As the deformation develops, abrupt brittle shear failure of the rigid part occurs. As a consequence, a high-speed landslide may develop (Fig. 16.3). The visco-elastic-plastic non-linear finite element method was used to simulate and validate the above mechanism. The results fully verify the mutual coordination of slope and failure mechanism of “locking segment in the conceptual model”.

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Fig. 16.3 A conceptual model of retailing wall collapse landslide mechanism

(3) Translational mechanism in almost horizontal strata Translational landslides characteristically develop in nearly horizontal bedrock. This kind of landslide occurs due to a combination of hydrostatic and uplift pressures (Zhang et al. 1994; Wang and Zhang 1983). Translational landslides are common in China, particularly in the Jurassic and Triassic interbedded mudstone and sandstone sequences with a near horizontal or gentle slope in the Three Gorges reservoir area and Sichuan basin. The typical characteristics of the landslide are sand and mudstone interbedded strata, which generally developed into a near horizontal or gentle slope. The sliding plane probably develops along with the interface of the mudstone and sandstone, the rear edge has the obvious fracture zone, and its width basically indicates the horizontal displacement of the landslide. The main triggering factor of such translational landslides is heavy rainfall. During heavy rainfall, water infiltrates into the cracks in the slope, causing high hydrostatic and uplift pressures along the sliding plane. When the water level in the cracks reaches a certain value, the landslide will be pushed forward and slip out by a combination of these pressures. Due to sliding along the bedding plane, the sliding body generally disintegrates, showing multiple gradation sliding surfaces, and the intact original stratigraphic structure is still retained inside the segmented block in the middle and the posterior division. A limit equilibrium criterion for translational landslides has been proposed by Zhang et al. (1994). hcr ¼


1=2 1 W 1  L2 tan2 /  8 cos a tan /  sin a tan / 2 cos a cx 2 cos a

ð16:2Þ where, W is the weight of a 1 m wide slide block (t/m); a is the dip angle of the sliding plane (a downslope dip gives a positive value, an upslope dip gives a negative value), with

0° < a < 10°; L is the length of the slide block; / is the friction angle of the sliding plane, not considering cohesion C; cx is the bulk density of water, qx g. If a ¼ 0, the above equation can be written as: hcr ¼


1=2 1 2 2 W 1 L tan /  8 tan /  tan / 2 cx 2

ð16:3Þ

(4) Sliding-bending-shearing mechanism This kind of landslide can be classified into two categories, according to the dip angle of the sliding plane: ① The dip angle of the sliding plane is less than the slope angle, so the outcrop of the potential sliding plane will be observed on the slope or in excavations. In this situation, the deformation mechanism is relatively simple and can be defined as creep-sliding and cracking or moving along a potential sliding plane. It is easy to identify the position of the sliding plane and corresponding stability condition. ② The potential sliding plane dips more steeply than the slope surface. Large-scale landslides always belong to this category and the potential damage is much larger than that caused by the first category. The formation of the sliding plane is a long, complex, geological, mechanical process and is very difficult to identify. The most effective mitigation measure is to strengthen and protect the resistant parts of the slope. The conceptual model of cataclinal lamellar rock slope failure is “sliding-bending-shearing” or “sliding-shearing”, which is closely related to the weak layer in the rock strata (Zhang et al. 1994; Huang et al. 2002a). According to the different deformation characteristics, the slope can be divided into two parts: ① the sliding part in the upper head and middle of the slope and ② the bending-swelling part in the lower (front) part. As shown in Fig. 16.4, in the area I the sliding force is generated and transferred to the lower part;

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Fig. 16.4 Deformation and failure conceptual model of cataclinal rock slopes (From Zhang et al. 1994)

whereas in area II the rock strata are pressed passively. In area I, the slope slides along the weak strata, driven by gravity. In area II, because the dip angle of the sliding plane is larger than the slope angle and the outcrop of the sliding plane is beneath the slope foot, the deformation is extruded and perpendicular to the strata. Once the bending-swelling deformation in area II develops, the resistant part will be broken by shearing, resulting in landslide. 2. Formation mechanism of debris flow The formation of debris flow is composed of starting and confluence processes. Both are organic and continuous processes, where the starting process is the key link. For the starting process of debris flow, the dynamic effect of a debris flow can be divided into a soil-forced and hydraulic debris flow. Formation of soil-forced debris flow refers to the process that saturates the soil, reduces the intensity, damage structure or liquefies under the hydraulic action of rainfall or runoff (both surface and underground runoff) and gravity to form debris flows. Formation of hydraulic debris flow is the

process that the soil mass, washed by the runoff, starts and forms debris flows. Its fluid property is very dilute. (1) Hydraulic dominant debris flows The cause of hydraulic debris flow is massive loose debris in the slope and channels which are encountered water scouring and other types of erosional effects gradually accumulate. When the content of solid material reaches a certain threshold, the fluid property would present some changes and become a fluid which is different from the general flow mechanical property and flow state. Many scholars have studied hydraulic debris flows and proposed relevant seismic damage model and predictor formula. For example, Takahashi and Das (2014) stated that the formation of debris flow occurred when the shearing force was greater than shearing strength to loose soil; and put forward the formula for judging the failure depth of the slope under the conditions of surface flow as well as without surface flow (Formulae 16.4 and 16.5) condition. Wang et al. (1990) obtained from field observation and laboratory

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experiments that strong erosion was also one of the reasons for debris flow Formation. According to the theory of fluid mechanics, the equation of flow movement on the surface of the accumulated body can be gotten, so that the shearing stress of scour can be calculated. Wang’s research has deepened Takahashi’s model; however, neither the influence of pore water pressure on shear strength nor the influence of dynamic changes of these parameters on slope stability is considered. The debris flow initiation model proposed by Takahashi belongs to the Coulomb failure model. There are six kinds of failure types of the saturated trench bed, and the shear stress and shear strength of the shallow slope are considered: s ¼ g sin h½C ðr  qÞ þ ðho þ aÞq

ð16:4Þ

sr ¼ g cos h½C ðr  qÞa tan / þ c

ð16:5Þ

In this formula: g is the gravitational acceleration; is the soil density; q is the water current density; c is the soil cohesion; u is the internal friction angle; h is the soil slope; h0 is the slope water depth; a is the depth from the soil surface to interior; C* is the Solid particle saturation concentration. While ds/da  dsr/da, soil body remains stable (Fig. 16.5a); while ds/da < dsr/da, soil body will be destroyed (Fig. 16.5b); while the shearing stress s = qgh0 sin h of the surface of soil body is greater than cohesion C, shear failure occurs in soil body. (2) Geotechnical dominant debris flow This type of debris flow is formed by the gravity action of the loose debris in the slope and channel. This loose debris is gradually wetted, infiltrated and soaked by precipitation and runoff and its water content increases. Consequently, its internal friction angle and cohesion decrease, the permeable flow, permeation force liquefy and destroy its stability to slide or flow along the slope. After a period of time and a distance of mixing, the solid and liquid are mixed to form a specific structure of debris flow. This is a type of movement that produced by water and solid matter and its gravity. The formation of debris flow on this solid debris requires a condition of shear stress value (s) larger than the solid debris

Fig. 16.5 Takahashi starting model of hydraulic debris flows

limit or critical shear stress (s0). The movement caused by the destruction of the balance condition of the soil due to the water filling will form the viscous debris flows with relatively solid content. The most typical process is the transformation of landslides into debris flows. Iverson (1997) pointed out there were three processes in the formation of debris flow from landslides: partial failures in large scale, liquefaction caused by excessive pore water pressure in the soil, and landslide potential energy into the internal vibration energy of the soil (e.g. increasing the temperature of particles). In this type of model, many scholars believe that the cause of soil failure is the increasing of pore water pressure in the soil; and its reason is the liquefaction of groundwater and local Kulun destruction in soil body. These result in the decreasing of cohesion. The safety factors of the slope body proposed by Iversion consist of three items: Fs = Tf + Tw + Tc  Tf represents the relationship between friction angle and the slope, descriptive of shear strength and gravity; Tw means ratio of the underground water level to strength ratio and gravity to express its intensity changes; and Tc represents the relationship between cohesion and shear strength. When Fs is greater than 1, landslide starts converting into debris flow; conversely, it is stable. d  @p tan / c Y  1 @y tan / Tf ¼ ; Tw ¼ ; Tc ¼ ð16:6Þ tan h ct Y sin h ct sin h In this formula: d is underground water level (Fig. 16.6), where hydraulic pressure is zero (p = 0), the water level is parallel to slope and surface hydraulic pressure is the same. ct in formulas Tw and Tc respectively means the total gross of saturated soil and unsaturated soil (below and above underground water) in average depth.

Fig. 16.6 Profile map and geometrical parameters of the infinite slope considering the direction of groundwater head in any direction

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16.3

Disaster Prevention

In order to mitigate losses caused by landslides, collapse and debris flow, monitoring and early warning systems and engineering control technologies are adopted.

16.3.1 Monitoring and Early Warning System on Landslide and Debris Flow 1. The key scientific and technological problems of monitoring and early warning system The key scientific and technological problems of monitoring and warning system are listed as follows: (1) Identification of potential hazards Accurate identification of potential hazard locations and their danger is the basis of monitoring and warning system. After clear knowledge of the potential hazard location and their extent of the danger, some key hazard points for monitoring and warning could be determinate. Then monitoring instruments and the related sensors will be installed in terms of the local geo-conditions. In the study area, the identification of potential geo-hazard is still a frontier science issue that has not been completely solved. (2) Critical indexes and threshold of the hazard formation The critical indexes and threshold of geo-hazard formation is the basis for the establishment of an early warning model and warning level division. Due to the complexity of the geo-hazard mechanism and dynamic process, the current critical index of landslides and debris flow consists of motivating factors, such as precipitation, and the factors referred to fluid and slope deformation, such as water level and displacement. And the critical thresholds are mainly determined by evaluation of historical geo-hazard. Considering the large difference in the formation of geo-hazard and their unrepeatability, identification of the critical indexes for geo-hazard formation and establishment of the critical thresholds are key scientific issues, which is challenging particularly in the case of scarcity in observations. (3) Evolution of hazards and monitoring/warning methods The monitoring contents of landslides and debris flow are selected according to the parameters used for the early warning and forecasting system. With the social and

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economic development, higher requirements on the accuracy, effectiveness and technical level of monitoring and early warning method are predominated. The past methods of warning based on a single indicator are unable to meet the current needs of geo-hazard reduction and social development. Determining the key factors in the process of geohazard evolution, developing relevant monitoring methods, and then forming the monitoring and warning method based on the geo-hazard evolution are the key issues of the next study. 2. Monitoring methods of landslide and debris flow (1) Monitoring methods of landslide and collapses Monitoring of landslide and collapse include the investigation of surface displacement, underground deformation, groundwater flow, crack development and so on. A. Surface displacement monitoring The monitoring of surface deformation is to trace the dynamic changes of landslide surface basically by observing horizontal and vertical displacement. In order to obtain data, instruments such as ‘total station’, GPS, ‘crack instrument’, ‘electronic level instrument’ and many other sensors are commonly used. The issues of extensive utilization of these instruments are high cost, the need for manual operation and difficulty of remote control. To overcome these drawbacks, several new technologies are developed. For example, high-precision and low-cost measurement array (Yang 2003) has made progress. In this technology, the real-time surface displacement with higher precision can be obtained by the processed array; the array node can be a fiber optic sensor or a GPS point. Another new technology is the positioning method of the ultra-wideband wireless sensor nets (Zhu et al. 2004). The low- cost wireless sensor is deployed on the surface and real-time three-dimensional displacements of the ground surface are calculated by using high-precision (centimetre-level) positioning technology. For some severe landslide bodies, a new type of micro-variable monitoring equipment Ground- based Radar (GBSAR) can be used. Using differential radar interferometry technology, GBSAR can obtain tiny deformation (submillimeter or 0.01 mm) in the target area. Compared with traditional monitoring methods, GBSAR does not need to touch the target area. The instrument is easy to install and data acquisition is convenient and this method has achieved good monitoring results (Caduff et al. 2014; Yue and Yue 2017).

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B. Underground deformation monitoring Tiltmeter is mainly designed to observe underground deformation. It can measure the inclinations of the wall at a different depth and then can be converted into displacement data. Fiber grating sensors (Dai et al. 2004) can also be used to measure underground deformation. when the optical fiber is bent, its internal laser transmission pattern will change. According to this characteristic, the underground displacement of the slope can be calculated by the curvature of fiber, and the displacement can also be obtained continuously. C. Groundwater monitoring Groundwater has an important influence on the stability of the slope. The traditional method to monitor groundwater is to put a water gauge or pore water pressure sensor after drilling. With the development of optical fiber technology, the optical fiber sensor or fiber grating sensor has been applied to monitor groundwater dynamism. D. Earth sound monitoring The method of earth sound monitoring is to determine the stability of rock and soil mass by measuring its strength and signal characteristics of stress wave which is released during the stress-induced failure of the rock mass. It can be used as an early method for monitoring and forecasting when the slope is in the extrusion stage, with tiny ground crack observed but inaccessible to measure (Li et al. 2008; Zhang et al. 2008). Monitoring instruments have ‘acoustic emitters’, ‘geophones’ etc., to collect the deformation and rupture of rock mass with the stress wave intensity and frequent signal discharge to analyze the deformation of the collapsing body. E. Video monitoring Video monitoring technology has been widely used in geo-hazard monitoring. Using this method, the overall or partial deformation of the slope can be visually observed. F. Vibration monitoring Vibration monitoring technology can measure the volume of collapse body by analyzing vibration signatures. When the land masses are moving, the vibration signals will be generated by the strike between the landslide body and the channel or the ground. Specifically, the vibration signals can be collected by the ‘three-axis accelerometer’. The whole monitoring system consists of a three-axis acceleration sensor, data collector, communication terminal and power

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supply system. Since the short period is available for collecting data in case landslide and collapse occur, the smaller frequency of sensor acquisition will have the better result as to we get. The specific parameters of the sensor acquisition frequency need to be determined by field testing. (2) Monitoring methods of debris flow There are mainly two kinds of time scales for early warning and alarm of debris flows. One is the early prediction based on debris flow formation process. In this method, the monitoring content is mainly rainfall and other parameters relevant to debris flow formation, which can be used to predict or suggest the possibility of debris flow in advance. The other is the early warning based on the movement of debris flow. In general, the advance time of the warning should be in units of 1 min. If the information, which signifies debris flow is about to occur or debris flow has occurred and is flowing in the ditch bed, is captured, warning signals based on the captured information will be triggered. In receipt of the warning signal, people can avoid in advance and evacuate to reduce casualties. The main monitoring contents of debris flow in these two time-scales include: A. Rainfall monitoring Rainfall monitoring is the basis of early warning of debris flow. It includes the monitoring of rainfall pattern on a regional basis. Satellite imagery and weather radar can provide spatial data of rainfall events, which not only provide information of precipitation parameters for small basins but also for a larger area for forecasting of debris flow occurrence which supports essential preparation for immediate warning. Meanwhile, ground monitoring methods, such as automatic rainfall station, make it possible to monitor rainfall process in a river basin and then analyze monitoring data immediately, which can provide a more reliable basis for the early warning and forecast of debris flow. At present, China has already achieved the forecasting of debris flow in a large-scale area with 3–36 h by numerical weather forecasting models and stationary meteorological satellite maps. Moreover, the ‘Doppler weather radar’ can be used for debris flow forecasting in small and medium-sized areas within 1–3 h and surface rainfall monitoring can be used for the warning and alarm of single ditch within 0.5–1 h (Zhang et al. 2005; Wei et al. 2007). B. Monitoring parameters of debris flow formation The monitoring of formation parameters of a debris flow can provide evidence for early warning of debris flow which

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The Landslide/Debris Flow and Control Technology in China

includes water content and pore water pressure in the soil, and its displacement. Soil water content can be measured by some apparatus such as Time Domain Reflectometer (TDR). Soil pore water pressure can be obtained by sensors, such as Piezoresistive Pressure Sensor, Semiconductor Pressure Sensor, Inductance Type Pressure Sensor, Capacitive Pressure Sensor, Resonant Pressure Sensor, Optical Fiber Sensor and so on. The measurement of soil displacement can refer to the measurement method of slope displacement. C. Monitoring parameters of debris flow motion The parameters characterizing debris flow movement are to use the information of debris flow, which has been detected in the upper reaches of the drainage basin to warn the downstream populace. Motion parameters include mud or water level, velocity and acoustic signals and so on. These monitoring data can be used to estimate the discharge of debris flow, determine the volume of debris flow, and estimate the flow velocity of debris flow and the time of arrival at the outlet. Using the monitoring data of debris flow movement process to predict the damage is a more accurate way. However, the time span for emergency management is limited for the ditches of the small watershed. Therefore, the choice of monitoring section in the upstream reaches is very important. The monitoring equipment aimed to motion parameter can be divided into two types contact equipment and non-contact equipment. Contact equipment perceives the movement and arrival of debris flow, and sends back the information to receptors, such as ‘broken line method’ and ‘impact force measurement method’. The broken line method is using the metal sensing line which located in the debris flow gully bed. Once the debris flow rushed off the line, the disconnection signal is sent back to achieve the alarm. Impact force measurement is using the impact force sensor arranged in the debris flow gully bed, and once the debris flows the impact signal is captured and sent to sound the alarm. The non-contact method includes but not limited to ‘earth sound method’, ‘ultrasound method’, and ‘infrared photography method’. Debris flow in the movement will produce vibration generated by the friction or impact on both sides of the flowing channel. This kind of vibration is known as debris flow voice, with its unique frequency which makes it available for the sensor to capture the ground sound. Then, by monitoring the value of the acceleration of earthquake, the magnitude of debris flow geo-hazard can be determined and used for early warning. Similarly, ultrasound alarm of debris flow is suspended with the ultrasound sensor above the ditch bed to monitor changes in the mud bed or water

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level. When the mud or water level is beyond a certain threshold, the alarm will activate. The velocity of a debris flow can be obtained from the time difference between two observation sections as debris flow body flowing through a certain distance in the valley and it is also monitored by the ultrasound velocity system. In recent years, camera and image transmission technologies have been used in the warning system of debris flow. One or two sets of infrared camera devices are mounted on both sides of a debris flow channel bed. According to the need of research, these cameras can work all day or work with other sensors (such as ground acoustics, sensing lines and so on) to stimulate the start of it. Camera and image transmission technologies enable real-time image transmission and can be used for hazard warning. 3. The thresholds and level of warning for the landslide and debris flow At present, although there is not much difference in the technical methods of landslide and debris flow monitoring domestically and abroad, the selection of warning level needs to be set according to the local situation. The content of the warning includes the analysis of monitoring data to determine the level of warning and publish warning information. For different scales of geo-hazard, selecting appropriate monitoring content, determining an appropriate threshold of warning, and setting a different warning level is necessary. In general, there are two scales for the warning of landslide and debris flow including regional scale and one-point scale. (1) Determination of threshold and classification of the landslide and debris flow in the regional scale In regional scale, based on the distribution of susceptibility or risk of landslide and debris flow, the warning and forecasting of geo-hazard can be carried out by analyzing the triggering conditions of geo- hazard, such as using the monitoring of rainfall and related forecasting threshold. Researches on rainfall models and thresholds of landslides had been done internationally. By determining the relationship between the rainfall level and the probability and scale of geo-hazards, rainfall model of landslide and debris flow can be established. In general, the antecedent rainfall and the antecedent moisture content are connected to the occurrence of geo-hazard. In some areas, the occurrence of geohazard is also affected by frozen soil, freeze-thaw and glacier ablation which indicate the significant change in temperature. The warning thresholds on a regional basis is generally determined as follows.

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(1) Geo-hazard investigation: it needs a detailed survey of the geological, geomorphological condition of the targeted geo-hazard in the local area. And then combined with the collected data of rainfall and temperature, statistical analysis are conducted for determining the critical conditions. (2) Contour analysis of rainstorm and temperature for geo-hazard: According to the monitoring data, the contour line of rainstorm or temperature are drawn; then the average value of the contour line in the geo- hazard area is worked out, which is regarded as the initial value of the critical condition. And according to a field survey of the mean rainstorm and temperature in the typical area of debris flow, the final critical threshold is determined by revising the initial value. Besides, relevant empirical formulas and models can be used to estimate if the monitoring data is insufficient. In terms of time process, the prediction and warning levels of landslides and debris flow on a regional scale can be divided into three levels: predict level (mid-long term), forecast level (short term) and alert level (early warning). The duration, spatial scales, method of obtaining indexes and emergency plans of various levels can be seen in Tables 16.1 and 16.2. (2) Threshold determination and early warning level of landslides and debris flow for individual hazard site For a single landslide and debris flow basin, accurate monitoring of key parameters can be established to build an accurate early warning value. And through the analysis of the triggering factors of geo-hazard, such as rainfall and temperature, the warning level can be determined and the warning can be made based on accurate monitoring data.

Table 16.1 The table of the prediction levels of landslides

The monitoring of landslide, debris flow and other geo-hazard themselves can also be the early-warning. For example, the development stage of the landslide is controlled by the mechanical properties of rock and soil, and its deformation process has obvious stage characteristics, which can be divided into three stages. (1) The initial stage of creep: it consists of a relatively long deformation period; the deformation of rock and soil is weak without cracks on the surface; only the trailing edge of large landslide appears tiny arc cracks, landslide monitoring and prediction has no practical significance in this stage. (2) The second creep stage: It is the compression stage of landslide formation; the surface deformation of the landslide is obvious ! cracks developing on the trailing edge and the boundary and the sliding surface is gradually forming ! completely occurs. This stage lasts for either a long period of time or a short period of time; the short period of time is 2–3 years, and the long period of time could be more than 10 years. This stage is an excellent opportunity for landslide monitoring and forecasting. Displacement analysis of landslide formation should focus on this stage. (3) The final creep stage: it refers to the accelerated deformation-slope failure. In this stage, the surface deformation of landslides is finalized; it takes place in less than 2–3 days or as longer as 10 days. It is very important for the nowcast of landslide and the early warning of the strenuous sliding time. Monitoring and early warning watcher can take this opportunity to conduct a comprehensive analysis of monitoring data of various aspects (such as displacement, inclination, etc.) and the macro phenomenon of the landslide. Making a relatively accurate prediction of the occurrence time of

Prediction level

Mid-long term (predict level)

Short term (forecast level)

Early warning (alert level)

Duration

Over 1 year

Several days to 1 year

Within several days

Spatial scale

Regional and one-point scale

One-point scale mainly, with less in regional scale

One-point scale

Method

Investigation and assessment

Investigation assessment and monitoring

Monitoring

Index

Danger level

Critical value

Alert value

Mean

Hazard division and database

Monitoring of displacement, earth sound and other physical quantity

Monitoring of displacement, earth sound and other physical quantity

Measurement for prediction

Control project or relocation, avoidance

Emergency engineering or conventional emergency shelters

Emergency shelter

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The Landslide/Debris Flow and Control Technology in China

Table 16.2 The table of the prediction levels of debris flow

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Prediction level

Mid-long term (predict level)

Short term (forecast level)

Early warning (alert level)

Duration

Over 1 year

Several hours to 1 year

Within several hours

Spatial scale

Sectional scale, single gully

Sectional scale, single gully

Single gully

Method

Investigation and assessment

Investigation, assessment and monitoring

Monitoring

Index

Danger level

Critical value

Alert value

Mean

Hazard division and database

Analyses of natural, geological, geomorphological and social factors in the watershed or gully; monitoring of the rainstorm

The monitoring equipment and alarm devices of rainfall, water level, earth sound and velocity

Measurement for prediction

Control project or relocation, avoidance

Emer gency engineering or conventional emergency shelters

Emergency shelter

landslide, displacement analysis is one of the important methods. Therefore, the classification of landslide warning level should be based on the actual monitoring data. The closer the geo-hazard occurs, the larger the scale and the greater the probability of geo-hazard, the higher the warning level could be made. The location of flash flood and debris flow happen often at a distance from the location of geo- hazard. Therefore, there is an interval between the geo-hazard occurrence process and geo-hazard-induced catastrophic process, and the time lag can be used for immediate warning. By monitoring geo-hazard movement in the upstream section, it serves to early warning for residents or other protection targets in the downstream. For example, the Dongchuan Debris Flow Observatory and Research Station realized successful warnings of debris flow in Jiangjiagou by monitoring debris flow volume, velocity and water level in the upstream of the basin by sensors and ultrasonic mud level alarms (Ye 1988). For long flow distance geo- hazard bodies, the real-time monitoring information in the upstream can be used to estimate the time, scale and damage when reaching the downstream through numerical calculation or simulation, and the geo- hazard warning level can be determined. The early- warning method based on real-time monitoring has the advantages of direct decision, easy and accurate, etc., but requires a high level of science and technology preparation. The larger the scale, the closer the time would be; the greater the damage, the higher the warning level would be. Thus, the determination of geo-hazard warning threshold requires a comprehensive analysis of historical data and a

proper understanding of geo- hazard triggering factors, and the division of the early warning level needs to be combined with actual geo- environment. Comprehensive and accurate monitoring is the basis for successful early warning.

16.3.2 Engineering Countermeasures of Landslide and Debris Flow 1. Principle of landslide and debris flow control (1) Landslide Landslide prevention and control mainly follows the principle of “prevention first and control in time”. Prevention first means in the site selection of railway, road alignment, factories, mines, towns and housing, avoiding the large and complex landslide area is very crucial, especially in the site where landslide may occur after the excavation. Control in time means landslides that have deformed, should follow the principle of “early control, strive to fully control; comprehensive planning, comprehensive control”, take the necessary engineering measures to control engineering timely. At the same time, landslide prevention and control engineering need to meet the requirement of technical feasibility and economic rationality, which means its prevention and control measures should be advanced, durable and reliable, convenient for construction, local material available and cost-effective. In addition, in the prevention and treatment of construction technology follow the principle of “dynamic designation, scientific construction”. Construction excavation can be used to investigate the geological background

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and characters of deformation slope and achieve dynamic designation. During the construction, the construction sequence and method should be properly adjusted according to the dynamic information of slope deformation and monitoring data so that the design and construction can be informatized scientifically. (2) Debris flow Debris flow prevention and control always take the small watershed as a research unit. Generally, the upper and middle reaches of a basin are treated as ecological environment control zone, and the downstream area is regarded as a geo-hazard control zone. Debris flow formation area is the key part of debris flow prevention and control and is the area of implementing active countermeasures. Debris flow fan area is the key zone for mitigation of debris flow geo-hazard loss, where the key area was deployed with passive protective facilities and soft control measures. In debris flow formation area, regulating debris flow initiation and reducing debris flow’s volume are a possible way to reduce geo-hazard. Debris flow prevention and control project should follow the principle of practicability, particularly, considering the ecological engineering measures if in the water source zone; the drainage and stabilizing measures are mainly placed in the landslide formation area; protecting measures are mainly in the transportation zone; drainage measures are mainly placed in the debris flow fan area. 2. Methods and techniques for preventing landslide (1) Prevention method of landslide Landslide prevention and control methods refer to the general planning and specific measures to prevention, mitigation and elimination of threats and damages caused by landslide, avalanche and rockfall in a certain area. It must firstly collect and analyze field data of landslide; secondly, it will analyze and calculate the characteristics, forming conditions, development and stability of the landslide; then it comes to determine the protection object and its scope, engineering level, the scale of investment, etc. Finally, prevention and control measures are suggested to make a comprehensive prevention and control program. According to the different natural environment, the type of landslide, the importance of protected objects and available investment volume that can be provided, there are usually the following four kinds of control programs for selection.

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A. Methods to Prevent landslide formation Buildings and other facilities built on the area threatened by landslide shall be relocated to beyond the area. If the important facilities can’t be transferred, necessary protection work should be done. The newly-built railway, highway, industrial and mining, urban and other major facilities should find safe engineering ground by careful route selection far from landslide geo-hazard-prone areas. If it can’t be avoided completely, potential slopes shall be treated in advance. Landslides and groundwater can be managed by lowering slope angle; setting anti-slide piles in the front of a landslide or constructing anti-skid walls at the leading edge can be used to fix unstable slope that may cause a landslide. B. Method to protect objects For a small amount of avalanche and rockfall along the slope, stone retaining walls or protective nets can be built in the middle of the slope. For roads, railways and irrigation channels, open cut tunnels or tunnel sheds could be built to protect them. C. Early warning and alarm system This countermeasure can be used as it is not easy to obtain specific physical parameters of an unstable slope by survey and the evidence of large-scale displacement are not observable at present or in the near future; there is not much funding for prevention and control in a short term. Observation shall be conducted on a deformed slope, and to install deformation monitoring equipment and measure deformation data. Regular inspection on the deformation body and its surroundings to trace the deformation dynamics of a slope and evaluation according to the deformation information are quite necessary. D. Protecting the natural geological environment According to the present situation and environmental characteristics of the landslide, we have worked out relevant regulations and decrees that protect the environment and reduce geo-hazards, strengthen management and adopt certain precautionary measures. The specific measures include: It is forbidden to build houses during the dangerous period of the landslide; strictly prohibit random digging; do well seepage control works in ponds, weirs and channels in mountainous areas; protect forest vegetation and prevent new slope deformation and destruction caused by forest destruction.

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Table 16.3 Classification of landslide control measures

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Type

Main engineering measures

Avoidance routing measures

(1) (2) (3) (4)

Drainage measures

(1) Surface drainage system

(1) The intercepting drain outside the sliding mass (2) The drainage ditch in the sliding mass (3) Anti-seepage of the natural ditch

(2) Underground drainage project

(1) (2) (3) (4) (5) (6) (7) (8) (9)

Mechanical balance

Optimize the route to avoid the landslide area Use tunnels to avoid landslides Bridge across the landslide Clear the sliding mass

(1) Weight reduction project (2) Counter pressure project (3) Retaining engineering

Slip soil improvement

The blind ditch of water cut Blind hole/ tunnel Oblique drilling group drainage Vertical hole group drainage Well group pumping Siphon drainage Slope revetment drain Slope blind drain Combined drainage of caves and holes

(1) (2) (3) (4) (5) (6)

(1) Anti-sliding retaining wall (2) Digging anti slip pile (3) Borehole landslide-resistance pile (4) Anchor anti-slide pile (5) Anchor cable (6) Slope revetment drain (7) Anti-slide tie (8) Rack pile (9) Frame pile (10) Frame anchor cable pile (11) Micropile group

Sliding zone grouting Sliding zone blasting Jet grouting pile Lime pile Lime-sand pile Roasting slip soil

In actual work, the above four countermeasures can be comprehensively used in terms of local conditions, and then the prevention and control plan which conforms to the law of landslide geo-hazard development is formulated.

and site selection. If we cannot avoid it, we should consider engineering measures to control it.

(2) Structural works of landslide

Drainage engineering is to discharge water on slope surface which has an important effect on the stability of the landslide through the surface drainage measures or underground drainage measures. The surface drainage is to displace surface water supplied by rainfall and the outcrops of groundwater (spring, wetland and another water body) on slope area through artificial channels. Among them, because the development of the cracks in the trailing edge of the landslide can be accelerated by the concentration of water in the ditch, the hillside interception ditch should be located at 3–5 m outside the scope of the possible expansion of landslide to prevent the landslide from expanding and destroying the

Control of landslides in China has formed a set of avoidance routing, drainage, mechanical balance and slip soil improvement of four renovated techniques (Table 16.3). A. Avoidance routing measures In the construction of highways, railways, mines, water conservancy and towns, if there are landslide hazard and potential landslide hazard problems, we should first consider avoiding the dangerous area of a landslide in route selection

B. Drainage engineering

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ditches; The use of open ditches and blind ditches can drain spring water, wetland water into the nearest drainage ditch. For any large-scale landslide with seepage, the underground drainage engineering must be used to regulate the groundwater, cut off the source of water supply out of slipping zone, reduce the subsurface water table, decrease the pore water pressure on the sliding zone soil and increase the shear strength, thereby increasing the stability of landslide. The regular underground drainage engineering measures are the blind ditch, the blind hole/tunnel, oblique (horizontal) /vertical hole group drainage, well group pumping, siphon drainage, slope revetment drain, etc. C. Anti-sliding retaining engineering Anti-slide retaining engineering is to restore and increase the inherent anti-slide force of landslide through engineering measures such as an anti-slide retaining wall, anti-slide pile, prestressed-anchor anti-slide cable, reinforced concrete anti-slide tie and embedded anti-slide pile, so as to achieve a new equilibrium and make landslide stable. Among them, the anti-slide retaining wall is usually gravity type, and it resists landslide thrust with its weight and increases foundation friction resistance. It is generally located at the toe of the landslide. The anti-slide pile is a kind of structure that

Fig. 16.7 The schematic diagram of the anti-slide pile (Northwest Institute of Scientific Research Institute of the Ministry of Railways, 1977). a cantilever pile; b fully buried pile

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inserts the pile into the stable layer below the sliding surface (belt). It uses its anchorage effect of the stable stratum rock to balance landslide thrust and stabilize landslide. The scheme of the structure is shown in Figure 16.7. Generally, it should be located at the thin section of the anti-slide section of landslide front. The common anchored anti-slide pile is to form prestressed anchor anti-slide cable pile with prestressed anchor cable in the pile head, to improve the stress condition of the pile, reduce the bending moment and shear force of the pile body, and to reduce the section and embedment depth of the pile. Reinforced concrete anti-slide tie is mainly used for the kind of shallow complete rock bedding landslide, but also can be used for thick sandstone or limestone landslide. The key point is in the upper and the lower of slip surface of the mudded intercalation or structural surface, to insert a short pile (one or more rows) to form a key pin to stabilize the landslide. The selection of embedded anti-slide piles is related to the terrain of the slope, the position of the pile and the ratio of the strength of the slide body to the strength of the sliding surface. D. Strengthening slope The key factors of the occurrence of landslide lie in the weak slip soil or potential slip soil with high water content and low

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239

Fig. 16.8 Prevention system of debris flow

strength. Therefore, it is also possible to improve the properties of slip soil by using the methods of blasting in the sliding zone, roasting for slip soil, sliding zone grouting and jet grouting pile, so as to increase shear strength and increase the anti-slide force of the landslide. 3. Method and technology of debris flow prevention (1) Methods of debris flow prevention There are various methods and measures to prevent and control debris flows. Generally, these measures can be divided into two categories: non- engineering prevention and control, and engineering prevention and control measures. Non-engineering prevention and control measures consider debris flow as a geo-hazard body under the circumstance of the social background of geo-hazard and the relationship between people and geo-hazard causes, social management measures, which don’t have the function of restraining or inhibiting debris flows. According to the origin and law of debris flow, man-made measures, which belong to engineering prevention and control measures, are taken to inhibit the formation and activities of debris flow so as to reduce debris flow event. The relationship between the two is shown in Fig. 16.8. Debris flow prevention and control system is usually designed to prevent and control debris flow. Debris flow prevention and control system: from the overall perspective, based on the occurrence conditions, basic properties, activity laws, development trend, hazard degree of debris flow and geologic, topographic, hydrological and atmospheric conditions, debris flow basin or area is planned, prevented and controlled uniformly by taking a series of practical and interrelated engineering measures with different functions,

monitoring and early warning measures as well as administrative measures in the corresponding sections to control gradually the occurrence and development of debris flow, reduce or eliminate geo- hazard, improve and restore the environment to build the new ecological balance. According to different protection purposes and requirements, debris flow prevention and control system are generally divided into the following three systems shown in Figure 16.9. A. System of Preventing Debris flow Occurrence (SPDO) In the formation area of debris flow, the basin is controlled comprehensively and fully by engineering measures such as slope management, trench management and water control, strict administrative measures and legal management measures to improve and restore the environment, control water and soil loss, stabilize the slope. Finally, debris flow will not be easy to occur. B. System of Controlling Debris flow Movement (SCDM) In the flowing section of debris flow, intercepting and regulating works are taken to reduce gradually the scale of debris flow, to separate solid matter from moisture in the debris flow fluid and reduce the solid matter. Finally, the debris flow discharges smoothly and safely to the downstream or accumulate in the designated area, and the life and property of the protected area will not be threatened or harmed. C. System of Precaution Debris flow Disaster (SPDD) Before debris flow occurs, a series of preventive measures are taken, including mid-term and long- term prediction for

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P. Cui

Fig. 16.9 Schematic diagram of debris flow prevention and control engineering system. 1. Basin boundary; 2. Intercepting drain and barrel drain of hillside; 3. Afforestation; 4. Check dam; 5. Revetment; 6. Sand-sediment dam; 7. Diversion channel; 8. Debris flows waste-shoal land; 9. Towns or other protective objects; 10. System of preventing debris flow occur; 11. System of controlling debris flow movement; 12. System of precaution debris flows disaster; 13. Therapy works of slope;

14. Therapy works of gully; 15. Therapy works of bottomland; Administrative and legal management measures; 17. Drainage works; 18. Intercepting works; 19. Precautionary measures before debris flow; 20. Monitoring and early warning measures in the process of debris flow; System of Preventing Debris flow Occur (SPDO); System of Controlling Debris flow Movement (SCDM); System of Precaution Debris flow Disaster (SPDD)

debris flow, temporary geo-hazard prediction, monitoring and early warning measures, maintaining and reinforcing existing prevention and control works, personnel evacuation, rescue and relief preparations measures, organization and management measures, to make sure that debris flow inflicts less harm. In general, large-scale and active debris flow gullies with serious potential geo-hazard can be regulated comprehensively in the basin, and the above three systems can be used simultaneously. For small scale, debris flow gullies with a low frequency of occurrence and less potential geo-hazard, the single prevention and control system or a combination of two systems can be taken to achieve the expected effect of geo-hazard prevention reduction according to the actual needs and investment of protection.

engineering measures. Engineering measures, mainly including geotechnical measures and planting measures, are used to restrict the formation and activity of debris flow so as to reduce debris flow initiation. Non-engineering measures, achieving the geo-hazard reduction by social management, doesn’t have the function of restraining or inhibiting debris flow. This section mainly introduces engineering measures.

(2) Techniques of debris flow prevention Prevention and control system of debris flow in China can be divided into two categories: non- engineering measures and

A. Geotechnical engineering measures Geotechnical measures for preventing and controlling debris flow: the initiation and movement of debris flow are controlled by source geo-material consolidation, diversion works, check dam, supporting engineering, drainage facility and debris flow silting ground works in clear water drainage area, debris flow formation areas, flowing area and accumulation area to reduce debris flow geo-hazard. The following sentences describe check dams, drainage works, and debris flow silting ground works.

16

The Landslide/Debris Flow and Control Technology in China

Debris flow interception works are a kind of structure retaining debris flow by regulating the development of debris flow and decreasing its outbreak scale, including building gravity sand-sediment dam, earth-rock dam, entity sand-sediment dam, gap-type sand-sediment dam, broach-type sand-sediment dam, check dam etc. and generally they are constructed on the course of debris flow formation area or formation-travelling area. To deal with small watershed, check dam specifically refers to small sand-sediment dams, which can consolidate gully bed and stabilize the slope, intercept sand, stop the flow and dissipate energy and enhance resistance, and the height of the dam is generally not more than 5 m. Debris flow drainage works refer to open groove-shaped structures with overflow capacity and planar shape, consisting of the existing natural channel as well as an artificial waterway, to transport debris flow to the non-hazardous downstream region and to control the damage in the flowing area and accumulation area. Drainage works including diversion channel, drainage ditches, diversion protection dike, aqueduct and so on, which are generally designed and arranged in flowing area and accumulation area. Debris flow accumulation works refer to certain measures which facilitate debris flow to arrive at a pre- selected area, to decelerate and stop the movement of debris torrent, to reduce peak flow of debris flow, to reduce the threat to protected objects in the accumulation area. The application conditions are as follows: the confluence section of the main river and the branch ditch of debris flow is a wide valley, and there is adequate space for deposition of transported sediment in the valley; the downstream of the main ditch is gentle and the valleys are open for the gully-type debris flow ditch; there is enough space to large amounts of sediment and no important man-made buildings or a large number of farmland nearby and intercepting mud and silting don’t create new potential geo-hazard threat. B. Plant engineering measures Plant engineering measures for preventing and controlling debris flow mainly include forestry measures, agricultural measures and animal habitation measures. Forestry measures are the main activities in plant engineering for preventing and controlling debris flow. Specifically, forestry measures include afforestation, expansion of forest coverage and management of woods (Zhong and Xie 2014). Plant engineering measures of preventing and controlling debris flow should consider soil and water conservation on inclined land in the basin and so agricultural measures mainly include turning slopes into terraces, planting forest belt against erosion and horizontal tillage. Animal husbandry measures are aimed at reducing the

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material source of debris flow and increase herdsman’s income by using grassland resources reasonably and conserving water and soil.

References Caduff R, Kos A, Schlunegger F et al (2014) Terrestrial radar interferometric measurement of hillslope deformation and atmospheric disturbances in the illgraben debris-flow catchment, Switzerland. IEEE Geosci Remote Sens Lett 11(2):434–438 Chen G, Wang Q (2004) Theoretical model and trend analysis on mountainous economic development stages in China. Acta Geogr Sin 59(2):303–310 Crosta GB, Imposimato S, Roddeman D (2009) Numerical modeling entrainment/deposition in rock and debris-avalanches. Eng Geol 109:135–145 Cui P (2015) Progress and prospects in research on mountain hazards in China. Prog Geogr 33(2):145–152 Cui P, Deng HY, Wang CH et al (2018) Mountain hazards. Higher Education Press, Beijing China Cui P, Liu SQ, Tang BX et al (2005) Debris flow study and prevention in National Park. Science Press, Beijing Dai ZY, Yuan Y, Liu YZ (2004) Research on monitoring system for landslides based on fiber optic strain sensing. Opt Optoeletron Technol 2(3):51–53 Delaney KB, Evans SG (2015) The 2000 Yigong landslide (Tibetan Plateau), rockslide-dammed lake and outburst flood: review, remote sensing analysis, and process modelling. Geomorphology 246:377– 393 Feng XS, Mou LH (2012) Engineering design and dynamic construction of No. 1 landslide regulation project of Erlang Mountain. Yellow River 43(19):26–29 Honda N, Egashira S (1997) Prediction of debris flow characteristics in mountain torrents. In: Chen CL (ed) Proceedings of the 1st international ASCE conference on debris-flow hazard mitigation: mechanics, prediction and assessment. American Society of Civil Engineers, New York, USA, pp 707–716 Hsu C (2006) Granular material flows-an overview. Powder Technol 162(3):208–229 Huang X, Garcia MH (1998) A Herschel-Bulkley model for mud flow down a slope. J Fluid Mech 374:305–333 Huang RQ, Zhang ZY, Wang ST (1991) Systematic engineering geology studying of the stability of high slope. Chengdu University of Technology Press, Chengdu Huang RQ, Deng RG (1993) Full Simulation Process for High Slope Substance Moving. Chengdu University of Technology Press, Chengdu Huang ZZ, Tang RC, Liu SL (2002a) Re-discussion of the seismogenic structure of the Diexi large earthquake in 1933 and the arc tectonics on Jiaochang, Sichuan Province. Earthq Res China 18(2):183–192 Huggel C, Kääb A, Haeberli W et al (2002b) Remote sensing based assessment of hazards from glacier lake outbursts: a case study in the Swiss Alps. Can Geotech J 39(2):316–330 Iverson RM (1997) The physics of debris flows. Rev Geophys 35 (3):245–296 Iverson RM (2009) Elements of an improved model of debris-flow motion. AIP conference proceedings. AIP 1145(1):9–16 Jin YL, Dai FC (2007) The mechanism of irrigation-induced landslides of loess. Chin J Geotech Eng 29(10):1493–1499 Jop P, Forterre Y, Pouliquen O (2005) Crucial role of sidewalls in granular surface flows: consequences for the rheology. J Fluid Mech 541:167–192

242 Legros F (2002) The mobility of long-runout landslides. Eng Geol 63 (3):301–331 Li M, Qin SQ, Ma P, Sun Q (2008) In-situ stress measurement with Kaiser effect of rock acoustic emission. J Eng Geol 16(6):833–838 O’Brien JS, Julien PY (1988) Laboratory analysis of mudflow properties. J Hydraul Eng 114(8):877–887 O’Brien JS, Julien PY, Fullerton WT (1993) Two-dimensional water flood and mudflow simulation. J Hydraul Eng 119(2):244–261 Ouyang CJ, Zhou K, Xu Q et al (2017) Dynamic analysis and numerical modeling of the 2015 catastrophic landslide of the construction waste landfill at Guangming, Shenzhen, China. Landslides 14(2):705–718 Pailha M, Pouliquen O (2009). A two-phase flow description of the initiation of underwater granular avalanches. J Fluid Mech 633:115–135 Pitman EB, Le L (2005) A two-fluid model for avalanche and debris flows. Philos Trans R Soc Lond A Math Phys Eng Sci 363 (1832):1573–1601 Pudasaini SP (2012) A general two-phase debris flow model. J Geophys Res Earth Surf 117 Savage SB (1983) Granular flows at high shear rates. In: Theory of dispersed multiphase flow, vol 339 Shang Y, Yang Z, Li L et al (2003) A super-large landslide in Tibet in 2000: background, occurrence, disaster, and origin. Geomorphology 54(3):225–243 Takahashi SA, Padilla C (2008) Rain-induced debris and mudflow triggering factors assessment in the santiago cordilleran foothills, central chile. Nat Hazards 47(2):201–215 Takahashi T, Das DK (2014) Debris flow: mechanics, prediction and countermeasures, 2nd edn. CRC Press, London Wang LS, Zhang ZY (1983) The basic geological mechanism model of slope rock body deformation and destruction. In: Collections of hydrological and engineering geology. Geological Publishing House Press

P. Cui Wang ZY, Lin BN, Zhang XY (1990) Instability of non-Newtonian open channel flow. J Mech 22(3):266–275 Wei FQ, Xue J, Jiang YJ et al (2007) The system of debris flow prediction with different time and space scales. J Mt Sci 25(5):616– 621 Xiong G (1996) Mechanics of viscous debris flow. PhD thesis, Tsinghua University, Beijing Yang XQ (2003) The application of optical fiber detector in reservoir dynamic monitoring. World Well Logging Technol 3:5–6 Ye HX (1988) Contact type railway mud-stone flow alarm sensor and study on its monitoring section’s position. J China Railw Soc 4:88– 97 Yue JP, Yue S (2017) Research progress of GBSAR monitoring technology. Modern surveying and mapping Zhang JH, Wei FQ, Cui P et al (2005) Multi-hierarchical precipitation-forecasting/monitoring system for prediction of debris flow. J Natl Hazard 14(5):74–78 Zhang SJ, Liu JP, Shi CY et al (2008) Study on precursory characteristics of rock failure based on acoustic emission experinent. Metal Mine 8:65–68 Zhang ZY, Liu HC (1990) Key engineering geology problem and research on Longyangxia hydropower station of Huanghe River. Chengdu University of Technology Press, Chengdu Zhang ZY, Wang ST, Wang LS (1994) Principle of engineering geology analysis. Geological Publishing House Press. Zhu L, Yuan X, Ge LJ et al (2004) A summarization of UWB wireless sensor networks. Meas Control Technol 12:1–4 Zhuang JQ, Cui P, Hu KH et al (2010) Characteristics of earthquake-triggered landslides and post-earthquake debris flows in Beichuan county. J Mt Sci 7(3):246–254 Zhong D, Xie H (2014) Debris flow disaster and control technology. Sichuan Science and Technology Press, Chengdu

Soil and Water Conservation Policies Change in the Yellow River Basin, China

17

Fei Wang, Duihu Ning, and Rui Li

17.1

Introduction

Soil erosion has important impacts, both on- site and off-site (Vignola et al. 2010; Wossink and Swinton 2007), including the reduction of soil depth, impairing the land’s productivity, and the transport of sediments, leading to deposition that degrades streams, lakes, and estuaries (Uri 2001). In China’s Loess Plateau, extensive soil erosion and water loss has historically induced soil degradation and soil water shortages, lowering crop yields, and exacerbating rural poverty, arable land and biodiversity loss on-site (Meng 1997). It has also induced sedimentation in the Yellow River (which has the greatest sediment load in the world), reducing reservoir capacity, causing the riverbed to rise, increasing the risk of flood disasters, increasing the maintenance costs of the river banks, and requiring more water to flush the sediment to the sea (Zhao 1996; Wu et al. 2005; Mu et al. 2004). Management of soil erosion in China’s Loess plateau has relied largely on the development and implementation of policies, which, over time have greatly decreased the sediment load of the Yellow River. Indeed, the mean annual suspended sediment load at Huayuankou declined from 1.36 billion tons in 1956–1970 to 0.23 billion tons in 1996–2010 (15 years) (Meng 1997; Tang 2004). This chapter examines how policy approaches have changed over time to achieve this improvement. Science and policy are both relevant to land management (Freyfogle and Newton 2002; Stringer and Dougill 2013). Although policy plays an increasingly important role in environment and resource management, and is considered fundamental to biodiversity conservation and watershed F. Wang (&)
R. Li Institute of Soil and Water Conservation, CAS/ MWR, NWUAF, Yangling, Shaanxi, China e-mail: [email protected]

management (Jansen et al. 2006; Miller et al. 2009), the success of policy initiatives is contingent on effective stakeholder engagement or public involvement (Cocklin et al. 2007; Stern and Mortimer 2009). Policies can include land rent change, voluntary or ‘soft’ policy based mainly on education, legal regulation, and national and local laws and actions (Bennett and Vitale 2001; Kelly 2006; Hanna et al. 2007; Gotmark et al. 2009; Stern and Mortimer 2009; Angelsen 2010). Policy in this chapter is defined as “a set of decisions which are oriented towards a long-term purpose or to a particular problem. Such decisions by governments are often embodied in legislation and usually apply to a country as a whole rather than to one part of it” (Sandford 1985). Research in the Yellow River Basin (YRB) to date has focused mostly on soil and water conservation (SWC) practices on the catchment slopes and how to dam the main stream to reduce sedimentation on the riverbed of the lower reach (YRCC ECR 1991; Meng 1997; Tang 2004). Research on the role of SWC policies is sorely lacking. While some analyses on SWC policy changes exist at a regional scale in China (Ding 1989; Guo 1995), they just describe the policy and pay very little attention to the impacts. In focusing on the co-evolution of SWC policy and human- environment linkages in the YRB in this chapter, we argue that it allows an opportunity for policy learning and to see what kinds of interventions have the desired environmental impacts. These lessons can then be applied in future policy development, helping to guide policy to better address some of the key drivers, pressures and impacts of soil erosion. The goal of this chapter is to analyze the SWC policy changes in the YRB since the foundation of the People’s Republic of China in 1949. This period fits well with document availability. The State law and policy on soil and water conservation, the relating actions and achievements of conservation are described.

D. Ning International Training and Research Centre On Erosion and Sedimentation, Beijing, China © Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_17

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The Yellow River Basin (YRB)

17.2.1 General Condition The Yellow River is the second largest river in China with a drainage area of 752,000 km2 and a length of 5464 km. It originates in the Qinghai-Tibet Plateau, flows through the Loess Plateau and the North China Plain (elevation below 100 m), and empties into the Bohai Sea. The basin covers 9 provinces or autonomous regions, was home to 110 million people in 2000, and accounted for around 9 percent of China’s total population (Giordano et al. 2004). The YRB covers a wide range of vegetation types and climatic zones because of this large area and elevation gradient. Mean annual precipitation in the basin is approximately 479 mm, but the regional and seasonal distribution is very uneven due to the great influence of the monsoon season. About 60% of precipitation falls in the rainy season from June to September (Zhao 1996).

17.2.2 Soil Erosion and Sediment Load The loess in the middle reaches of YRB is very prone to erosion, causing the sediment load and concentration of the Yellow River to be very large (Zhao 1996; Walling and Webb 1996). The mean annual sediment load was 1.6 billion tons and the average sediment concentration 37.8 kg/m3 based on measured data at Sanmenxia Hydrologic Station from 1919 to 1986 (Zhao 1996). Over time, sediment deposition in the downstream river channel has caused the riverbed to be up to 10 m higher than the surrounding land surface in some places, a condition known as a “suspended river” or “perched river” (Wu et al. 2005). Over thousands of years of Chinese history, frequent catastrophic floods in the YRB have resulted in tremendous losses of life and property.

17.3

Law and Policy on Soil and Water Conservation

Yellow River Water Resources Commission (YRCC) and research institutes including the Chinese Academy of Sciences (CAS). The types of document included directives, decisions, reports, regulations and laws. According to the importance of their functions in conducting SWC actions, 22 important formal documents were selected (Table 17.1). Most policies are at the basin scale, and some are at the national scale with powerful effects in YRB, such as P14, P19 and P21.

17.3.2 The Stages of Policy We divided our analysis of SWC policy into three stages according to two important events: the publication of the Act of Soil and Water Conservation at the small watershed scale (P10) and Law of The People’s Republic of China on Water and Soil Conservation (P14). This provides a novel approach, different from that taken in other researches (Ding 1989; CAS SSTlp 1991b; YRCC UMB 1993; Guo 1995; CCoG 1999). The stages thus distinguished are as follows: Stage 1 (1949–1979): Historical flood disasters and the desire for hydropower and irrigation made the government and basin manager plan to change the Yellow River from a harmful river into a beneficial river. Stage 2 (1980–1990): Integrated control, taking a small watershed as a wholistic unit was introduced (P10), reflecting a need to explore natural resources and build on a systematic management principle of watersheds based on previous experiences including soil erosion control practices on the slopes, and sediment retention and flash flood control with dams in the gullies. Stage 3 (1991 till now): Since the issue of SWC law in 1991 (P14), the aims and tasks of SWC policy became broader and more central. Prevention of new lands being destroyed began to become the priority, after which technology and other approaches were considered. The policy or movement of eco- civilization construction was put forward in 2015 and great progress has already appeared. The integrated management is still the core, but a new stage will be formed.

17.3.1 Law and Policy on Soil and Water Conservation

17.4 Documents relating to SWC policy in the Yellow River were sourced from national administrative departments including the Government Administration Council (GAC, from October 21, 1949 to September 27, 1954, the then highest administrative department equivalent to the State Council), National People’s Congress (NPC), the State Council (SC), Ministry of Water Resources (MWR), Ministry of Agriculture (MOA), managing department of basins including

The Policy Evolution in Each Stage Through a DPSIR Framework

17.4.1 DPSIR Framework DPSIR framework (OECD 1993; Gabrielsen and Bosch 2003; Gobin et al. 2004; Borja et al. 2006; Martins et al. 2012) provides the conceptual framework for better understanding the complex relationship between soil erosion and policy responses.

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Soil and Water Conservation Policies Change …

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Table 17.1 Selected policy documents on SWC from 1949 to 2011 in YRB

*

Code

Issued by

Issued date

Policy

P1

GAC

Dec 19, 1952

Directive to arouse the masses for drought control and drought resistance and popularization of soil and water conservation

P2

YRCC

Feb 15, 1953

The decision to harness the Yellow River in 1953

P3

MWR

Dec 31, 1953

Summary of the water conservancy in the last four years and the policy and task in future

P4

MWR, CAS, et al

May to Dec, 1953

Working report of soil and water conservation in northwest China of investigation mission (Draft)

P5

NPC Standing Committee

Jul 30, 1955

The decision to integrate planning for radical solution of disasters and exploration of water conservancy of the Yellow River

P6

SC

Jul 24, 1957

The provisional outline of soil and water conservation of the People’s Republic of China

P7

YRCC

Aug 2, 1958

The soil and water conservation planning in the middle reaches of the Yellow River from 1958 to 1962 (draft)

P8

SWCC of SC

Apr 13, 1962

Report on strengthening the soil and water conservation

P9

SC

Apr 18, 1963

Decision on the soil and water conservation in the middle reaches of the Yellow River

P10

MWR

Apr 29, 1980

Act of soil and water conservation at the small watershed scale

P11

SC

Jun 3, 1982

The regulations on the work of water and soil conservation

P12

NWLCG of SC

Sep, 1983

The provisional rule to strengthen the soil and water conservation in key areas of water and soil loss

P13

CPC CC and SC

Jan 1, 1985

The ten policies on further animating the rural economic

P14

NPC Standing Committee

Jun 29, 1991 (issued) and Dec 25, 2010 (revised)

Law of The People’s Republic of China on water and soil conservation

P15

SC

Aug 1, 1993

Implementation of the law of the People’s Republic of Soil and water conservation

P16

SC

Jan 7, 1999

National plan for eco-environmental improvement

P17

SC

Dec 21, 2000

National program for eco-environmental protection

P18

SC

Jan 20, 2003

Regulations on conversion of farmland to forest

P19

SC

Aug 9, 2007

Circular of policy on conversion of farmland to forest

P20

CPC CC and SC

Dec 31, 2011

Decision on accelerating water conservancy reform and development

P21

CPC CC and SC

Apr 25, 2015

Decision to accelerate the eco-civilization construction

P22

SC

Oct 18, 2015

Approval of national soil and water conservation planning (2015–2030)

*

Pn in this paper means the relative document in this table Abbreviation CPC CC: Central Committee of the Chinese Communist Party; NWLCG: National Water and Land Conservation Work Coordination Group of State Council, a branch of the State Council founded in 1982 and cancelled in 1988, and a National Water Resources and Soil Conservation Leading Group in 1988; SFA: State Forestry Administration

In the context of its application in the present study, it makes it possible for the authors to explore the effects of responses on drivers, pressures, states and impacts. Driving forces for SWC in the YRB include both natural and socio-economic factors that disrupt the environment’s ability to provide ecosystem services, including e.g. food, fuel and forage (Fig. 17.1). Shortages of these services drive environmental pressures such as cultivation on slopes, deforestation and over-grazing. This leads to soil erosion that has both on-and off-site effects. Society nevertheless responds with various policy measures such as regulation and information provision, and in some cases, negative strategies that could worsen the pressures.

Feedbacks between responses mean that the ways in which the problem of soil erosion is handled could affect driving forces (R1), pressures (R2) and/ or states (R3). Responses to states (R3) might thereby have limited effect as they merely addresses symptoms of land degradation, whereas positive responses to the driving forces (R1) could improve the regional economic and food condition over the long-run as a solution to soil erosion control. These kinds of relationships form the focus of our analysis. Even though climate change in YRB could drive changes in soil erosion (Cenacchi et al. 2011), human influence has been (and still is) the most important factor in driving soil erosion (Zhao 1996; Wang et al. 2007). The human

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Fig. 17.1 DPSIR Framework for soil and water conservation in YRB Main DPSIR framework with description of each factors; R1, R2 and R3 mean the 3 responses to Driving forces, Pressures, States. In this chapter, we mainly discussed the policy aspects of responses

population in YRB demands food and fuel for survival. Poverty and poor transportation determine whether local people can get the necessities for life from other regions. In this study, we select food shortages as the main driving force (Li 1996; Zhao 1996) and regional floods as the main impacts that we analyze (Luo and Le 1996; Zhao 1996). We firstly identified and analyzed historical documents on SWC policies, and used these to elucidate the state, impact and driving forces to describe the problems, demands and the suggested or encouraged solutions that could influence the problems by addressing driving forces, pressures and/or states. Subsequently, the implementation and effects of specific SWC measures were identified, considering especially the policy objectives, tasks and principles, and the institutional set-up (and responsibilities). The main practices (measures and actions) at each stage were compared to allow detailed analysis of the evolution of SWC policy.

like plains and check-dam land (lands built up behind check-dams and flat enough for agriculture, normally the gradient is gentler than 1°), and sloping croplands with gradient 25° respectively. To analyze the impacts of soil erosion and water loss, flood data was included based on available historical records from 1841 to 1990 (Luo and Le 1996). The rush of runoff and sedimentation in the lower reach induced by soil and water losses were the main causes of floods in this region. Flood levels were classed according to the frequency of flood disaster possibility, and great flood disaster, big flood disaster and normal flood disaster were rarer than 5%, 5– 10% and 10–20% probabilities respectively. Annual data on runoff and suspended sediment load in 1956–2010 at Huayuankou Hydrological Station were abstracted from the China River Sediment Bulletin (published by MWR) from 2000 (with datasets before 2000 as appendix) to 2010 to describe the river characteristics. The watershed of the station is 730,036 km2, accounting for 97.1% of the whole basin.

17.4.2 Data for Policy Change Analysis A 62-year annual dataset from 1949 to 2010 of total population, area of grain crops, grain yield, average yield and average grain per person of 4 main provinces of Shaanxi, Gansu, Shanxi Province and Ningxia Hui Autonomous Region (which cover most of the basin) (NBS NEGSD 2010) was analyzed to detect the driving forces of food production and supply. Data of cropland gradients of the 4 provinces in 1986 (CAS SSTlp 1990a) were used to show the state of land use and cover in relation to soil erosion. The gradient of croplands distinguished 6 categories of land: flat lands- including level terraces, alluvial lands along the rivers

17.4.3 The Change of Policy With DPSIR Framework Policies mainly embody the positive responses of humans to other elements in the DPSIR framework. In this section, the continuous changes of driving forces, pressures, states and impacts are described to sketch the complex interconnections between conditions and processes. Special attention is given to dynamics over the three policy stages distinguished because such factors changed continuously and the interactions between elements varied in intensity.

17

Soil and Water Conservation Policies Change …

1. Driving forces evolution In Stage 1, because of the great effect of long- term conflicts including World War II and the Chinese Civil Wars, living conditions in the YRB and whole of China were very poor before 1949. There were 36.86 million people in the 4 provinces in 1949, the average yield of grain was very low (0.8 t/ha in 1949) and the average food availability expressed as grain per person was 224.8 kg (Fig. 17.2). This meant local people had to cultivate more and more land for food because traditional agricultural productivity was very low. The area of grain crops increased from 10.94 million ha in 1949 to 12.97 million ha in 1966 (the largest in the whole research period), a change of up to 18.5%. However, the population increased even faster in this period, to 57.33 million people (a 55.5% increase) by 1966 and 75.12 million people by 1979 (Fig. 17.2). In Stage 2, the population continued to increase to 89.35 million people in 1990 (Fig. 17.2). Average yields increased from just 2.0 t/ha in 1980. to about 2.6 t/ha in 1990. However, the total area of grain crops in the YRB decreased to 11.02 million ha during this period, which combined with the increase in population, means that food production has seen no great improvement (fluctuating around 300 kg per person since 1979). Nevertheless, it has proven to be enough to increase food security in this region, infrastructure development and increases in incomes have enabled people to purchase food and meat produced in other regions, but the imported food was not enough for local people and animal husbandry (CAS SSTlp 1991b).

Fig. 17.2 Population, area of grain crops and grain yield of the 4 provinces in 1949–2010

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In Stage 3, the population increase continued and in 2010 was up to 105.02 million people (about 2.85 times the population in 1949) (Fig. 17.2). However, the rate of population change has started to slow down since 1990. The area under cultivation of grain crops continued to decrease after 1991, and although average yields continued to rise, total grain production started to stabilize. Another important driving force has been the economic development in China since 1988. In the four provinces, the gross regional product (GRP) of primary industry (including crops, forests, animal husbandry, sidelines and inner water fishery) increased fast, but nevertheless the share of direct output of agriculture reduced. Local people could earn more money from other industries and purchase food from other regions, leading to a decline of human pressure on the land. 2. Pressures evolution In Stage 1, pressures were mainly exerted by the expansion of cropland on slopes because of population increases and food shortage, deforestation due to new cultivation and rural fuel, and over-grazing as more livestock were added in the hope of producing more meat and higher incomes. Animal husbandry was a traditional livelihood activity in the Loess Plateau because there were plenty of areas supporting grasses that were not feasible for cultivation both because of steep slopes and poor soil properties (CAS SSTlp 1991a). The share of cropland in the Loess Plateau was more than 30.0% in 1986 (CAS SSTlp 1990a), but most cropland was on sloping land. In the 4 selected provinces in 1986 (Fig.17.3), the share of flat lands, sloping croplands with

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from 1999 to 2006 in YRB involving 8 million households and 30 million people, with investment from central government amounting to 5.1 billion US$ (38.8 billion Yuan RMB) (Gu and Gu 2007). 3. States and impacts evolution

Fig. 17.3 Gradient of cropland of the 4 provinces in YRB in 1996

gradient 25° were 18.06%, 36.17%, 9.22%, 16.47%, 14.80% and 5.28%, respectively. Croplands steeper than 7° accounted for 36.55% of cultivated lands and 11.68% of the whole area, respectively. This condition was the result of long-term implementation of SWC practices on the slopes before 1986 (P1, P2, P7 and P9), and evidence of the degree of human pressure on the land in preceding decades. Despite a gradual decline in the cultivated area after 1966, the availability of grasses has never been sufficient because of the over-grazing (very intensive free-ranging livestock, e.g. about 1.5 goats per ha of grassland in 1998 in Yan’an City (Shaanxi Bureau of Statistics 1999). Domestic animals could pull out the roots of grasses and some small shrubs, and even eat the bark of shrubs and trees. This causes destruction of the natural vegetation more widely, leaving the soil loose and exposed (Zhao 1996). In Stage 2 and Stage 3, the pressure on land reduced because of SWC practices driven by policies. For example, 225.6 thousand km2 of degraded land was controlled from 1949 to 2009, but more than 80% of these works were realized since 1970 (Sun et al., 2009). The SWC practices could last for several years to many decades and induced less soil erosion and sediment load in the river. There were 8.27 million ha of sloping cropland converted Table 17.2 Flood disasters in the Yellow River Basin from 1841 to 1990

Period

The continuing driving forces and pressures induced changes in land use and the land degradation state (Fig. 17.1). Cultivated land is the main source of sediment of the Yellow River, contributing more than 50% of the sediment load (Tang 2004; Lü et al. 2012). With cultivation of steeper slopes, the soil erosion rate increased dramatically; on newly cultivated lands steeper than 25° and 35°, the annual soil erosion rate was around 15 thousand t/km2 and 30 thousand t/km2 respectively (Tang 2004) because of the natural intensive storms and very little vegetation cover (CAS SSTlp 1990b). The state and impact relating to SWC are separate elements in the DPSIR framework, but they are closely interlinked. The state of land degradation refers to soil erosion, water loss, nutrient loss, land surface broken (Fig. 17.1), while the impacts of such state include 2 different types. The on-site impacts include soil loss, drought, nutrient depletion, lower productivity, ecosystem degradation, etc. Off-site impacts include sedimentation in dams and riverbeds, water level rising, increased flood risk, disasters, costs for banks construction, etc. The sediment load and floods of the Yellow River were selected as impacts to reflect the soil and water losses. (1) Flood disasters Flood disasters have throughout history constituted the main impact of the degraded state of land in the YRB. Floods occurred every year from 1841 to 1949 (before Stage 1) affecting on average 149 counties annually in China. There were 288 flood disasters during that period, and 42 of the events were in YRB (Luo and Le 1996). Flood disasters in YRB occurred very frequently (2.3–5.7 events per decade in 1871–1960). Most of them were big or great disasters (Table 17.2). Flood disasters affected all areas from the upper to the lower reaches, but most flood disasters were in

Leve

Total number

Frequency

Great

Big

Normal

Events per decade

1841–1870

5

2

3

10

3.3

1871–1900

8

9

0

17

5.7

1901–1930

4

2

1

7

2.3

1931–1960

6

1

4

11

3.7

1961–1990

2

1

1

4

1.3

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Soil and Water Conservation Policies Change …

the densely populated and intensively used lower reaches. Damages resulting from flood disasters have been terrible in the history of the YRB. For example, the great flood disasters in 1933 and 1935 affected 67 counties and 27 counties respectively and affected 3.64 million and 3.41 million people. More than 18 thousand died in 1933 and 3065 people died in 1935 (Luo and Le 1996). Even though the flood disasters were primarily induced by weather conditions, the raising of the riverbed due to sediment deposition in the lower reach has aggravated flood risk (Zhao 1996). Furthermore, the river banks in the lower reach have seen a great influx of people, dramatically worsening potential damages of flood disasters and reminding us all the time of the risk of catastrophes even if there were very few flood disasters in Stage 2 and 3. (2) Sediment load change in each stage In Stage 1, the mean sediment load between 1956–1979 was 1.29 billion tons at Huayuankou Station, although peaks of more than 2 billion tons occurred in 1958, 1959 and 1967 (Fig. 17.4). The total sediment load in this stage amounted to 2.99 billion tons. At the beginning of Stage 1 (1950–1959), the sediment load of the Yellow River was very high (1.78 billion tons on average) (YRCC UMB, 1993), and sediment deposition in the river bed of the lower reach amounted to 473 million tons annually (Xu 2004), raising the river bed and increasing flood risk. In Stages 2 and 3, the mean sediment load was reduced to 764 million tons and 366 million tons respectively, reflecting

Fig. 17.4 Annual runoff and sediment load change at Huayuankou hydrologic station (YR) in 1956–2010

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a 40.7% and 71.6% reduction compared to Stage 1. The sediment load was less than 100 million tons in 2006, 2007, 2008 and 2009, meaning that soil erosion and sediment load were controlled very effectively. These findings also imply that the human response should now change focus (Fig. 17.1).

17.4.4 Policy Responses in Different Stages 1. Policy responses in Stage 1 Before Wan mentioned SWC in 1936, people did not link flood disasters to soil erosion of the upper streams. They considered flooding a natural process, and the long-term strategy to prevent flood disasters focused on flushing the sediment into the sea and re- constructing the river banks (YRCC ECR 1991). Even until 1955, people believed “it was proved that the flooding and sediment was endless in the Yellow River and the sediment should be flushed away” (P5). But the new understanding of SWC promoted a more integrated policy, controlling food supply, flood prevention and environmental protection (Table 17.1). (1) Main aims and tasks After the establishment of PRC, SWC was listed as an independent action of agricultural development (Ding 1989). Since 1952, it was mainly implemented to combat drought (P1), as a complementary strategy to improve grain

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production with more irrigation (P5). It was also regarded as the key to “change the Yellow River from a harmful river to a beneficial river” because it allowed the rational use of water for irrigation and hydropower exploration (P3). Some responses were more compulsory and included legal elements. For example, as response to pressures (R2, Fig. 17.1), cultivation of new cropland on steep slopes was forbidden on land steeper than 25° (P1). It was soon realized that to obtain synergies between R3 and R2 responses required the integrated control and treatment of the entire watershed. The geographical focus changed from specific branches with very severe erosion problems (P1) to the regional scale, covering an area from Hekou Town (Inner Mongolia) to Longmen Town (Shaanxi Province) (about 100 thousand km2) (P4, P8). SWC also started paying attention to driving forces (R1) through local economic development and integrated river management in 1955 (P5, P6, P7), considering management or control both for reduction of flooding and improvement of hydropower. The SWC of the Loess Plateau was thus highlighted in national planning. The policy stated: “For the objectives of development of mountain region, improvement of living standards, radical solution of disasters and exploration of water conservancy of the Yellow River, we should try to conserve water and soil, improve food production, promote the development of each of the industries of agriculture, forestry and animal husbandry, and do our utmost to use the water and soil resources (P5)”. (2) Institutional aspects The economic condition was poor and the managing ability of local and central governments was weak at the beginning of P. R. China. The main stakeholders responsible for SWC were the local farmers in 1952 (P1). Since 1961, the CSWC SC pointed out that “to conserve soil and water based on production teams, the major power of it is local people and secondary is assistance from the state”. SWCC and YRCC of MWR stated the same main institutional set-up, i.e. local people with assistance from the government (P8, P9). (3) Strategic options In Stage 1, a policy on “overall survey, test and demonstration, progressive and careful extension” was put forward in 1953 (P4). It was a rational policy and implied SWC should have scientific and cautious strategies and that they needed more research and testing. Then, 1st SWC Meeting of YRCC of MWR and SWCC of SC launched a policy of “comprehensive planning, overall development, control the slopes and gullies together and concentrated control” in 1956 and 1957 respectively (P5, P6). It not only covered the

F. Wang et al.

fundamental principles of planning, measurement and development, but also targeted what was considered more important to control at the time: the slopes and gullies in areas with poor economic and social conditions and flooding risks. There were many integrated multidisciplinary investigations to identify the soil erosion types, intensity and distribution, rural economic condition, SWC practices and planning, regional development and so on, to support policy implementation. For example, the investigation organized by MWR and YRCC with 500 experts from CAS, MOA, MOF and their branch institutes (P4); the integrated investigation organized by CAS for SWC in the middle reaches of the Yellow River from 1955 to 1958 on a pilot area of 350 km2. Before the climax of SWC implemented by the local people, the 3rd National SWC Meeting developed the policy to “pay the same attention to prevention and control, conserve the results of control, develop the area and quality together for the final control and stable and high yield of crops” in 1958 according to the aims of agriculture development that time (P8). Construction of reservoirs and dams for siltation was put forward as fast and decisive practice as a response to states (R3, Fig. 17.1) in the beginning (P1, P2, P3, P5), but later SWC practices on the slopes became more important than practices further downstream (P1, P2, P7 and P9). Documents pointed specifically to “SWC on the sloping croplands first” (P9), to reduce soil erosion and the sediment load of the rivers. But soon after that, in 1961, the SWCC of SC changed it: “the main target area is the sloping cropland and the control of sloping cropland should be combined with the control of uncultivated slopes, wind erosion area and gullies through revegetation practices, such as grass-planting, reforestation and closure” (P8). The main SWC practices became vegetative practices. From 1970 to 1977, MWR paid more attention to land construction to improve agricultural conditions. (4) Evaluation of effects of policy responses In Stage 1, SWC played an important role for the recovery and development of the local economy after the long social upheaval of World War II and the Chinese Civil Wars before the foundation of P. R. China in 1949. Average yields were initially fluctuating around 1 t/ha (1949-1969) but almost doubled in the last 10 years of Stage 1 (Fig. 17.2). There were large disparities however: crop yield on the sloping cropland was about 0.9 t/ha, but amounted to 3.5 t/ha on the terraces and check-dam land (YRCC UMB, 1993). Even though the extent of SWC developed quickly, it could not keep up with the requirements of society. Some actions, such as tillage on steep slopes induced greater soil erosion, and showed negative impacts.

17

Soil and Water Conservation Policies Change …

Over-ambitious planning of SWC was put forward as policy against the social background of “the Great Leap Forward Movement” from 1958 to 1960. The government wanted to radically solve problems of flooding disasters and exploration of water for irrigation and hydropower resources of the Yellow River (P7). The mean suspended sediment load at Huayuankou was 1.36 billion tons in 1956-1970 (15 years), illustrating some success in reducing sedimentation, and flood disasters were reduced (Table 17.2). However, some policies were not implemented according to plan. The main reason was that the SWC policy was too bold to implement, e.g. a good policy based on “entire planning, integrated measures and continuing implementation” in 1958 (P7) set a grand task to change agricultural conditions and control the entire area affected by soil erosion (158.9 thousand km2 before 1958 and the remaining 355.3 thousand km2 before 1964). Such integrated control would require no soil erosion on the slopes and no runoff out of the gullies under the conditions of ① daily rainfall up to 100 mm in Inner Mongolia Autonomy Region, Ningxia Hui Autonomy Region, central area of Gansu Province and Qinghai Province, ② daily rainfall up to 150 mm in west region of Shanxi Province, north region of Shaanxi Province, west region and south region of Gansu Province, and ③ daily rainfall up to 200 mm in Henan Province. It was neither feasible nor necessary in terms of either physical process or economic capacity. It is a typical example of policy failure because planning was too ambitious and far beyond of the ability of society and citizens (Jansen et al. 2006). 2. Policy responses in Stage 2 (1) Main aims and tasks With the development of SWC, the main aims and tasks evolved to become more complex, starting with separate aims to reduce sediment load and flooding, improve production, and move towards integrated watershed control and more holistic resource and environmental management. In Stage 2, the main aim was to efficiently improve SWC based on multi- disciplinary appraisal which treated small watersheds as special complex natural and economic units in this region (P10, P11). MWR put forward a policy in which “integrated control should treat a small watershed as a unit with overall planning and different efficient on-site practices” (Guo 1995; Duan 1999; CCoG 1999; MWR SWCD 1995). “Hills, water, forest, cropland and roads” were harnessed together (P10) for holistic control (R1-R3) and long-term benefits (P11, P14, P16 and P18). A second characteristic response in Stage 2 was the identification of key areas for SWC. The area of high erodibility is so large

251

that it was necessary to select some areas to prioritize according to the soil erosion rate (R3) and impacts. Dedicated responses to pressures (R2) were also considered: cultivation of reclaimed land with slopes between 5° and 25° required permission from the local government (P13, P14); logging without permission or digging for the roots of herbs was forbidden to avoid new soil erosion (P6, P12, P14, P16, and P17). Those engaging in these activities were fined and even imprisoned if the consequences were bad enough (P14, P15). (2) Institutional aspects The increasingly integrated approach to SWC in this stage could not be implemented by local farmers themselves because the capacities of investment, technology and labor of local farmers were insufficient to carry out the envisaged engineering works like check-dams and roads. SC presented a structure of organizations involved in SWC and their duties to enable implementing this policy and stated the principle to encourage communities to participate in SWC, which was until then mainly carried out by citizens, assisted by the State (P11). (3) Strategic options In Stage 2, the strategy emphasized the direction, suitability, integration and sustainability of SWC (P10). Engineering and vegetation practices were especially important, using grass and shrubs first and then trees. The slopes and gullies were to be controlled with different efficient practices; starting with overall planning, the control process should start with severely eroded areas and only subsequently continue with less eroded areas. Cropland on slopes steeper than 25° should be gradually converted for forestry and animal husbandry, and the government should provide cheaper food to the local people if the food production there was not enough (P13). The focal area also shifted to consider smaller coarse sediment source areas (78.6 thousand km2) from where the sediment particles are big and difficult transfer to the sea (YRCC EC 2002). This helped the government to improve the efficiency of sediment load control of the Yellow River. SWC was mainly characterized as taking a small watershed as a whole unit to plan and control with integrated control measures. As the functions and suitability of SWC practices vary greatly depending on soil erosion intensity, soil moisture and vegetation in different sites, integrated control with different proper practices is necessary both for SWC and agricultural development (Fig. 17.5). Integrated control measures considering a small watershed as a whole have been put forward since 1950s (Tang 2004), but the

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F. Wang et al.

Fig. 17.5 Integrate control of Majiagou Watershed, Ansai County, China Photo from Wang Fei, 2010. Terraces mainly are on the moderate to gentle slopes, afforestation on the steep slopes and small gullies, and check-dam for small watershed. The check-dam land formatted after a long-term siltation and is flat and fertile enough for cultivation. The drainage system is set to prevent the flash floods induced by extreme storms

systematic generalization, extension and implementation as action (P10) began in 1980 (Guo 1995; MWR SWCD 1995; CCoG 1999; Duan 1999).

(3) Policy responses in Stage 3

(4) Evaluation of effects of policy responses

In Stage 3, the aim of the law was “the prevention and control of soil erosion, the protection and rational utilization of water and soil resources, the mitigation of flood disasters, drought and sandstorms, the improvement of the ecological environment and the development of production (P14, Article 1)”. The law expressed the policy as “the state shall, in relation to the work of water and soil conservation, implement the policy of prevention first, overall planning, comprehensive prevention and control, adoption of measures suited to local conditions, strengthening management and stress on beneficial results (Article 4, Chap. 1)” (P14) and changed the former policy of “paying the same attention to prevention and control” (P6) to prioritizing prevention. Under the P14, a series of laws and regulations were issued according to this policy. Furthermore, the National Program for Eco-environmental Protection and Regulations on Conversion of Farmland to Forest were published by the State Council in 2000 and 2003 respectively (P17, P18). These stated that SWC is not only an action for harnessing the Yellow River and controlling soil erosion (i.e. R3 response) for agricultural development, but that it is a fundamental action to restore ecosystems and safeguard the environment, economy and society (R1-3 response).

Since the implementation of the Act of Soil and Water Conservation at the small watershed scale (P10), there were 5 phases which overall involved surveying, planning and measurement of 164 small watersheds in YRB as experimental sites. During the process of implementation, many technical regulations, procedures for planning, investment, research, checking and qualification were brought forward that promoted the implementation of policy institutionally (Cao 2007). Besides, an investigation of the water conservancy management department and the integrated investigation team for SWC of the Loess Plateau was organized by CAS in 1983. A project on integrated control of the Loess Plateau was carried out by CAS from 1986 and began to identify an overall strategy of soil erosion control and rural development with real experimental and demonstration watersheds till 2000 (Li 1996; Li and Sun 1998; Wang et al. 2005). The sediment load of the Yellow River decreased from an average of 1.29 billion tons to 764 million tons during this stage (Fig. 17.3) and the cropland area and grain yield increased (Fig. 17.2).

(1) Main aims and tasks

17

Soil and Water Conservation Policies Change …

Policies were especially targeting reducing the driving force (R1 response) of intensification of food production and encouraging the development of various renewable energies to relieve fuel shortages (P14, and revised version in 2010). Pressures were also tackled specifically (R2 responses); initially, local people who converted their cropland into grasslands and forests could get subsidies of grain for food and cash for seedlings directly from the central government (P18). Later, they could get cash through a new policy on conversion of farmland to forest (P19). Most recently, a policy on ecological compensation for SWC was put forward formally in 2010 and could promote SWC in many regions that currently experience a lower benefits return (P20). The eco-civilization was put forward in China as a new vision of society evolution, and the respect for, conformity to and protection of the nature is the main principle in China and the clean rivers and green mountains are as valuable as mountains of gold and silver (P21). (2) Institutional aspects Since 1991, responsibility for SWC shifted to become the vital duty of government and the responsibility of multiple stakeholders. The law (P14) made it clear that “All organizations and individuals should have the obligation to protect water and soil resources, prevent and control soil erosion, and have the right to report against any unit or individual that damages water and soil resources and causes soil erosion” (Article 3, Chap. 1), “The State Council and the local people’s government at various levels should regard the work of water and soil conservation as an important duty, and adopt measures to ensure the prevention and control of soil erosion” (Article 5, Chapter 1), and put the missions of the planning of SWC into the development plan of public economy and society (Article 7, Chapter 1). Legally, SWC should be carried out by whoever was responsible for causing the loss of soil and water; the conservation measures should rely on scientific technologies and personnel training to achieve progress; while the administrations of water resources management and management organizations of SWC supervision should be responsible for examining and approving the SWC programs (P14). State policies to help rural businesses and farmers to conserve soil and water followed a principle that whoever took charge managed the conservation and benefited from it. For example, construction companies and individuals were responsible for the losses of soil and water they caused and for the SWC measures to counter the losses (Guo 1995; Duan 1999). The

253

national soil and water conservation plan was developed by a committee composed by 6 ministries including MWR, State Development and Reform Commission (SDRC), Ministry of Finance (MOF), Ministry of Environmental Protection (MEP), Ministry of Agriculture (MOA) and State Forestry Administration (SFA), and SWC has already been treated as a foundation of eco-civilization construction (P22). (3) Strategic options Prevention and containment of soil erosion has been given higher priority than controlling the on- going erosion problems in the Law of Soil and Water Conservation of China (P14). Ecological recovery and environmental construction have become the main purpose of implementing SWC (P17, P18). The “Grain for Green Project” (P18), in which the local farmers could get food and cash subsidies from the government after they converted sloping cropland into forests and grasslands, has been widely implemented in this region (Cao et al. 2009). SWC has been considered not only as an action of “soil protection and sediment control of the Yellow River”, but as the basic engineering approach towards the “Eco-environmental Construction of China” for enhanced ecological functions, natural resource management and the sustainable development of China (P16, P17, P18, P19). (4) Evaluation of effects of policy responses SWC progress and benefits in the YRB were great in the last 60 years (Sun et al. 2009): the area of grain crops decreased, but food production increased stably, satisfying the changing demands linked to population growth (Fig. 17.1). The sediment load of the Yellow River at Huayuankou Station decreased greatly with a very significant linear trend (Fig. 17.4), and about 30% of the decrease in sediment load (350-450 million tons annually) has been attributed to SWC on the slopes (Meng 1997; Tang 2004). The ecological, economic and social benefits of conversion of farmland to forest (well known as the “Grain for Green Project”) were very clear: e.g. vegetation cover in the Loess Plateau increased quickly, and the land area with a vegetation cover of more than 30% changed from 90

A1

A2

A2

A3

A4-1

F

Deep, 50–90

A1

A2

A3

A4

A4-1

F

Shallow, 20–50

A2

A3

A4

A4

A4-2

F

Very shallow, < 20

A4

A4

A4

A4/F1

F

F

Unrestricted

P

Note (1) Land suitable for agriculture and animal husbandry A1: Class 1 land, unrestricted agricultural use A2: Class 2 land, needs moderate soil and water conservation treatments. A3: Class 3 land, needs intense soil and water conservation treatments. A4: Class 4 land, suited for long-term crop and needs intense soil and water conservation treatment. (2) Land suitable for forest F: Class 5 land, suited for forestry, not agriculture. F1: suited for forest with either severe soil erosion problems or consolidated parent material. (3) Conservation and preservation land P: Class 6 lanmd, exposed parent material, severe soil erosion problems and landslides that needs intense soil and water conservation treatments to reduce disaster occurrence. (4) Land excluded from land classification but suited for forestry only Table 18.4 Soil and water conservation treatments for land suitable for agriculture and animal husbandry

Cultivation method

Class 1

Class 2

Class 3

Class 4 4–1

4–2

Intense, short-term

H, BT, BBT

BT, G, or S

BT,G or S

BT, G, or S

BT

Intense, long-term

H, BT, BBT

H, G, or S

A,G or S

BT, H, G or S

BT

Perennial fruit crop

H, BT, BBT

H, G, or S

A, G or S

H, G or S

BT, H, S

Pasture

H, BT, BBT

H, BBT

H, G

H, G

G

Note H: hillside ditch; BT: bench terrace; BBT: broad based terrace; G: grass strip; S: stone wall

operations and traditional farming methods are (Hu and Lee 1995):

slopes of less than 40%. Grasses may be established on the bottom and sides of hillside ditches to stabilize them and reduce maintenance costs.

1. Bench terraces (Fig. 18.5) 3. Stone walls (Fig. 18.7) Three types of terrace (reverse-slope, outward- slope, and level) are most popular in Taiwan. Because of its high construction cost and inconvenience for machine operation, terrace has not been used in large areas since 1970 except for places growing clean cultivated crops, cash crops and high valued crops. In terraced orchards, farm paths and link roads are subsequently constructed between terraces for convenient farm management . Wi th t he se improvements, terraced orchards have been reported to achieve more than 62% cost reduction from transportation and labor saving. 2. Hillside ditches (Fig. 18.6) These triangular or V-shaped ditches run across the face of the hill in the direction of the contour. They shorten the length of hillside slope and divert runoff water, prevent the formation of gullies, reduce sheet and rill erosion, retain moisture in areas where rainfall is low, and provide pathways for small farm machines. They are generally used in

In stony areas, the rocks can be put to good use by constructing walls along the contour of the slope. The walls can trap soil and debris washed down the slope and eventually forms bench terraces after several years. 4. Broad based terraces (Fig. 18.8) These are constructed on gentle slopes of less than 12%, provide good water conservation measures, have the same interval design as the hillside ditch with gradients of 0–0.6% and with a maximum allowed length of 300 m. 5. Agronomic cover crops and mulching (Fig. 18.9) In Taiwan, grass cover and mulch are usually applied in two ways: ① covering the entire area, and ② establishing strips at intervals between fruit tree rows. Grasses serve as ground cover and as mulch which can effectively suppress

18

Degradation Hazards and Conservation Approaches …

263

Fig. 18.5 Schematic diagram of bench terrace (FFTC 1995)

Fig. 18.6 Schematic diagram of hillside ditch (FFTC 1995)

Fig. 18.7 Schematic diagram of stone wall (FFTC 1995)

weeds. Herbicides are seldom required. There is no soil contamination and often makes zero tillage possible. Bahia grass is one of the recommended cover crops because among

other features, it is easy to plant, fast growing, and high survival rate. When combined with hillside ditches, yields significant effect in reducing soil loss and runoff.

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K.-F. A. Lo

Fig. 18.8 Schematic diagram of broad based terrace (FFTC 1995)

6. Grassed waterways (Fig. 18.10) Grassed waterways have been used successfully on steep slopes in Taiwan although they were originally developed for moderate slopes in the United States. They provide the safest drainage for areas where the soil parent material is soft shale or mudstone.

These include loose- rock dams, single-fence dams, double-fence dams, sausage gabion dams, and dams built of concrete, masonry and earth fill. 8. Conservation practices for major crops The conservation practices suggested for major crops grown on slopelands are summarized in Table 18.5.

7. Gully control (Fig. 18.11) 9. Crop-livestock farming Gullies easily form when the soil parent material is soft shale or mudstone. In Taiwan, small gullies are prevented from expanding by cutting hillside ditches to divert runoff, as well as filling and shaping the gully to turn it into a grassed waterway. Gully formation can also be controlled by check dams which may be permanent or semi-permanent.

Fig. 18.9 Schematic diagram of cover crop and mulching (FFTC 1995)

Soils of Taiwan’s hilly lands are generally shallow and of low fertility. Hence, a combined crop-livestock farming system from which animal manure can be used for soil improvement may be adopted. Dairies, pig farms and beef cattle are common on slopelands. Grazing is allowed on

18

Degradation Hazards and Conservation Approaches …

265

Fig. 18.10 Schematic diagram of grassed waterway (FFTC 1995)

Fig. 18.11 Gully control using permanent check dams Courtesy of Forestry Management Dept., Nantou County, Taiwan

Table 18.5 Recommended soil conservation practices for major crops in Taiwan Crops

Hillside ditch with Cover crop and mulching

Citrus





Tea




Mango





Lichi





Bench terrace Contour close planting

Grass barriers

Banana




Apple





Mulberry





Upland crops Note X denotes good; XX denotes very good

Reserve-slope

Level

Outward-slope



















Pineapple

Stubble mulching



































266

K.-F. A. Lo

natural pastures under forest trees or on riverbanks. Agricultural by-products such bamboo shoot shells, tomato pulp, brewer’s grain and discarded vegetables are used as fattening supplements. Goat and deer are not encouraged by the government but some farmers find them profitable.

10. Agroforestry Combining agricultural and forest crops on the same space, at the same time or under a sequential schedule are commonly practiced on slopelands (Hu and Lee 1995). The practice is encouraged in Taiwan to balance the needs of society and protection of the environment. Under a tree planting program jointly undertaken by the government and tree farmers, tree planters were allowed to intercrop cash crops two years before and three years after tree planting. Thus, squatters on slopelands became legal tree planters who could enjoy a share of the harvested agricultural and forestry products. The trees in the reforestation program include fast-growing trees, bamboos and fruit trees. Betel nut (Arecha catechu) is also popular; however it has a shallow root system, demands full even light, depletes water and nutrients rapidly and provides little protection against soil erosion or landslides. Although its cultivation is profitable, it is not encouraged by the government. In northern Taiwan, tea which is a perennial plant is intercropped with Taiwan acacia or pine trees. The shade improves the quality of Jasmine tea. In area where tea is intercropped with betel nut palm, higher returns are obtained from the two crops.

18.3

Integrated Watershed Conservation and Restoration

Taiwan is located on the earthquake belt of the Pacific Rim and so has fragile geological formations and suffers frequent earthquakes. The island is also hit by typhoons, heavy rain, or torrential downpours brought by southwestern air currents associated with typhoons. In recent years, climate change has brought more frequent heavy rains with more frequent landslide disasters. A comprehensive approach, referred to as “integrated river basin management” has become an evident necessity. “Key Infrastructure and Sustainable Development” Projects are, therefore, promoted by the Soil and Water Conservation Bureau as a “Water and Green Construction Plan” which incorporates comprehensive disaster prevention measures for slopeland areas (SWCB 2015). This contrasts with former categorization of single flooding or sediment disaster event, reflecting the predominance of combined events. Some successful comprehensive programs

include management of flood-prone areas, reservoir watershed conservation, and promoting carbon reduction. Successful case studies Four successful cases, each from the eastern, northern, north-central, and central part of Taiwan are presented to illustrate the effectiveness of integrated watershed Conservation and Restoration Program in conserving soil and water resources in Taiwan slopelands (Fig. 18.12). 1. Second phase of the debris flow disaster prevention project at Baibao River This project was located in Hualien County, in the eastern part of Taiwan. The project was designed with local conditions in mind and natural materials were used as much as possible (SWCB 2009). In compliance with the idea of energy conservation and carbon reduction, the construction blended in with the surrounding environment to reduce their impact on the ecology and to create a diverse habitat for local species. The practices utilized in this project are Permeable Dam (Fig. 18.13), Wooden Check Dam (Fig. 18.14), and Arched Stone Ground Sill and Stone Spur Dike (Fig. 18.15). 2. Dredging project upstream of Niulan River along Ren’an Village This project won the 2010–2011 Excellent Agricultural Construction Project Award for Slopeland Management and Disaster Prevention. It was carried out in Guanxi Township, Hsinchu County (north- central part of Taiwan) (SWCB 2010) and adopted the compound section design for the construction of stone revetments (Fig. 18.16). It used locally retrieved boulders to reduce the use of concrete and successfully reduced the amount of sediment transport downstream, achieving the goals of energy conservation and carbon reduction while fulfilling its ecological and flood prevention goals. 3. Slopeland conservation project upstream of the Dajiao River This project won the 9th Public Works Gold Medal Award for Excellent Construction for Water Conservancy in 2008. It was designed to mitigate the damage from several recurring typhoons and torrential rains over several years, thus controlling landslides upstream of the Dajiao River, Taipei City (SWCB 2008a). It used boulders to create a variety of revetments and built a series of ground sills to ensure constant flows on the surface of the river and achieve the goal of balancing both ecological and flood prevention needs (Fig. 18.17). In addition, the Bureau created

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Degradation Hazards and Conservation Approaches …

267

Fig. 18.12 Location of cities and counties of Taiwan

environments such as deep pools, shallow pools, sand bars, jet streams, slow streams, and deep streams. 4. Second phase of the Zhonghe Bridge downstream dredging project at the Choutengkeng River project, so that it could create an environment suitable for aquatic species. This project won the 9th Public Works Gold Medal Award for Excellent Construction for Sustainability, Energy Conservation and Carbon Reduction in 2008. The Choutengkeng Watershed is located in Zhonghe Village, Xinshe Township, Taichung County (central part of Taiwan and

supplies water to the Choutengkeng River via tributaries along the entire length of the river and covers an area of 1320 ha. A combination of loosened soil structure caused by the 921 Earthquake in 1999 and torrential rains brought by Typhoon Toraji in July 2001 resulted in multiple landslides in the Choutengkeng Watershed (SWCB 2008b). The Soil and Water Conservation Bureau (the Bureau) estimated that the landslides covered an area of 68.85 ha. The sediment moved downstream and silted up across the river and its tributaries. In July 2004, as a result of Typhoon Mindulle and the flood that followed on July 2nd, sediment silted up Choutengkeng River to the necking zone, causing Zhonghe Village (the project section) to endure about 1–2 m of flood.

268

K.-F. A. Lo

Fig. 18.13 Permeable dam at Baibao Stream

The Bureau reduced the use of cement and used natural materials as much as possible when carrying out the ground-sill.

18.4

Rural Villages Rejuvenation

Rejuvenation Program was proposed as one of the 12 major projects. This program aims to create prosperous new rural villages all over the country. In its early stages, the Bureau seeks to introduce new mechanisms to revitalize local communities and to encourage villagers, depending on their needs, to participate in sustainable development, based on the concept of comprehensive planning.

18.4.1 Motivating Local People In 1987, the Soil and Water Conservation Bureau created the Slopeland Village Comprehensive Development Plan, followed by the Agricultural and Fishing Village Community Development Plan in 1993. These plans were combined under the Comprehensive Village Development Plan in 1998 which accomplished many positive results. After the 921 Earthquake in 1999, many rural villages were devastated. While gathering information from different sources and range of services, the Bureau implemented the New Rural Village Program between 2001 and 2008. This program aims at establishing a bottom- up approach to stimulate grassroots stakeholders to join forces to promote comprehensive development. In 2009, the Rural Villages

18.4.2 Successful Case Studies Based on the 2010 Rural Rejuvenation Act, the SWCB has promoted and helped farmers all over Taiwan to rebuild villages with hope, vitality, health and happiness. Through 2011, 1920 communities have participated in training, for a total of 87,431 attendees, and have guided the drafting of 115 community plans for rural rejuvenation. A total of 51 community infrastructure projects (both software and hardware), and also urgent and essentialen vironmental improvement projects in 431 rural communities have been implemented. Four successful cases, each from the eastern, northern, central, and southern part of Taiwan illustrate the

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Degradation Hazards and Conservation Approaches …

Fig. 18.14 Wooden check dam at Baibao Stream

Fig. 18.15 Stone ground sill and dike at Baibao Stream

269

270

K.-F. A. Lo

Fig. 18.16 Construction of stone revetments at Niulan Stream

effectiveness of the Rural Villages Rejuvenation Program in conserving soil and water resources in Taiwan’s sloplands (Fig. 18.12). These case studies are detailed for Yilan County, New Taipei City, Changhua County, and Pingtung County by ZCDA (2011), GoCDA (2011), PCDA (2011), GaCDA (2011); respectively.

18.5

Future Vision

Soil and water conservation is essential for sustainable slopeland agriculture in Taiwan. Over the years, several soil and water conservation programs have been implemented to assist farmers in constructing drainage channels, agricultural road and paths. Along with other programs such as Integrated Soil Conservation and Land Use, Slopeland Agricultural Management, Slopeland Conservation and Utilization Loan, and Integrated Development of Slopeland Farming Communities are aimed at enhancing income and welfare of farmers and rural communities as well as improving agricultural production and living conditions in

the rural areas. In addition, some slopeland areas with proper conservation and infrastructure facilities may be developed into sightseeing and recreational spots for both visitors and tourists from the urban sectors. With the passage of the “ Soil and Water Conservation Act”, efforts have been focused on solving the problems of illegal cultivation of betel palm, tea, vegetables and improper non-agricultural developments on steep hillslopes. Appropriate planning and effective control and regulation of land uses on land capability classification has been initiated. Policy, legislation and regulations must be formulated to refocus soil and water conservation program in the future. Proper policies and legislations need to be amended to reclaim cultivated slopelands on highly erodible soils. Programs should be developed to provide appropriate compensation for farmers or land owners. Mandatory compliance legislation should also be put in place for farmers and land owners to carry out timely conservation plan and to conduct necessary maintenance on highly erodible slopelands in order to be eligible for continued government support.

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Degradation Hazards and Conservation Approaches …

271

Fig. 18.17 Revetments and ground sills construction upstream of Dajiao Stream

New research and development in soil and water conservation is necessary for effective land stewardship. Better know-how must be developed for decisions on rational non-agricultural development and cultivation of highly profitable cash crops such as tea, vegetables, betel palm on environmentally sensitive and fragile slopelands. Innovative methods must be developed for assessing soil and water conservation projects’ benefit cost ratio, and better integration of land and water management activities on individual farms, small watersheds, and large drainage basins. Over the past decade, global warming has resulted in changes in climate around the world. Innovative thinking and method are necessary to combat such challenges. Taiwan has accumulated more than fifty years of knowledge and practical experience in solving soil and water conservation problems on steep slopelands. This knowledge and experience are extremely valuable to similar regions in problem identification and solution development for both agricultural and non-agricultural uses of steep slopelands. The task of soil and water conservation is urgent, comprehensive, and essential to promote integrated watershed conservation and restoration. In addition, it is also necessary to combine expert knowledge and resources from many different fields in order to improve the capability and the autonomous

action from local organizations. Sustainable rural village development along with environmental protection security may be achieved only with integrated considerations on ecology, landscape, livelihood, culture and development. The role of soil and water conservation should be further emphasized through properly designed public relations, information, education, participation, awareness and support. After all, conservation is everybody’s business. Only with an all-out effort from every citizen can the goal of conserving our soil and water resources be successfully attained.

References Chan CC (1999) Slopeland capability classification in Taiwan. In: Proceedings of the international workshop on slopeland use capability, PCARRD, Los Banos, Philippines, p 25 Chen ZS, Asio VB, Yi DF (1999) Characteristics and genesis of volcanic soils along a topo-sequence under a subtropical climate in Taiwan. Soil Sci 164:510–525 Food and Fertilizer Technology Center for the Asian and Pacific Region (FFTC) (1995) Soil conservation handbook, FFTC Book Series, vol 11, p 412 Gaoshi Community Development Association (GaCDA) (2011) Report on rural village rejuvenation project at gaoshi community. Pingtung County, p 91

272 Gongrong Community Development Association (GoCDA) (2011) Report on rural village rejuvenation project at gongrong community. New Taipei City, p 98 Hse LC (1972) The description and classification of Taiwan soils. FFTC Tech Bull 8:1–15 Hsu S, Shin CZ, Wu WL et al (1979) Experiment on soil conservation practices for upland crop on slopeland (2nd report). J Soil Water Conserv 10(2):97–109 Hu SC, Lee SW (1995) Erosion control practices for steep upland fields in Taiwan. FFTC Ext Bull 401:1–12 Lo KFA (1999) Suitability assessment of slopeland for sustainable use. In: Proceedings of the international workshop on slopeland use capability, PCARRD. Los Banos, Philippines, p 22 Mou n t a i n Agr i c u l t u re R e se a rc h De ve l o p m e nt B ur e a u (MARDB) (1983) Taiwan Slopeland Resources Investigation Report, p 154 Pinghe Community Development Association (PCDA) (2011) Report on rural village rejuvenation project at Pinghe community. Changhua County, p 141 Soil and Water Conservation Bureau (SWCB) (2008a) Project Report of the Upstream Dajiao River Slopeland Conservation, p 144

K.-F. A. Lo Soil and Water Conservation Bureau (SWCB) (2008b) Project report of the second phase of the zhonghe bridge downstream dredging at the Choutengkeng river, p 154 Soil and Water Conservation Bureau (SWCB) (2009) Project report of the second phase of debris flow disaster prevention at Baibao, p 64 Soil and Water Conservation Bureau (SWCB) (2010) Project report of the upstream Niulan river dredging along Ren’an village, p 88 Soil and Water Conservation Bureau (SWCB) (2015) Annual Report. Council of Agriculture, p 116 Wang ST (1972) Soils of Taiwan and their utilization. FFTC Ext Bull 14:1–15 Wang ST (1986) Soils of slopeland and their management in Taiwan. Proc Korea-China Bilateral Sym on Reclamation and Soil Conserv of Sloped Farm Land Rural Dev Admin Korea, pp 132–149 Wu CC (1995) Effectiveness of vegetative residue on soil and water conservation for steep sloping orchards. Proceedings of the international seminar on soil conservation and management for sustainable slopeland farming, Pingtung, Taiwan: II-3–2-II-3–18 Zhongshan Community Development Association (ZCDA) (2011) Report on rural village rejuvenation project at Zhongshan Community, Yilan County, p 57. http://www.gov.tw/OrgInfo/ORPF-ORG02.aspx?OID=2.16.886.101.20003. http://en.swsb.gov.tw/content/ index.aspx?Parser-1,3,18

Soil Conservation Practices and Efforts Made to Combat Desertification in the United Arab Emirates

19

Shabbir Ahmad Shahid and Tareefa S. Alsumaiti

The United Arab Emirates is in the hyper-arid desert environment where evapotranspiration exceeds precipitation and Aridic (L. aridus, dry) and Torric (L. torridus, hot) moisture regimes have been identified. The soils are dominantly sandy “Entisols” and highly vulnerable to wind erosion leading to loss of fertile soil and organic matter and exposure of hard pans. These sandy landscapes need attention for their conservation to obtain ecosystem services. Wind erosion is considered the main land degradation factor. Other land degradation indicators identified are, soil salinization (coastal land and agricultural farms), plant roots exposure, surface armor layer, loss of fertile soil and organic matter etc. To evaluate the mechanisms of particles movement in UAE desert, through particle size analyses, it is determined that saltation is the dominant mechanism of mass soil movement, followed by surface creep and the suspension movement, suggesting the dust storms phenomenon is an external environmental influence. The first FAO-ITPS world’s soil status report released in 2015 clearly indicated “the majority of the world’s soil resources are in only fair, poor or very poor conditions, and that conditions are getting worse in far more cases than they are improving”, this is great concern globally and especially the region where loose sandy soils are dominant, water scarcity and prolong drought exists, such as the UAE. The UN General Assembly in 1994 approved the Convention to Combat Desertification (CCD), however, the UNCCD entered into force on 26 December, 1996. The UAE has joined the UNCCD on 21 October 1998 and became a member on 19 January 1999. The UAE has made significant efforts to protect fragile environment through soil conservation practices, such as afforestation of over 330,000 ha “Greening The Deserts”, though irrigated. Recent study on irrigation optimization in afforestation trees S. A. Shahid (&) United Arab Emirates, Ajman, UAE T. S. Alsumaiti Geography and Urban Planning Department, College of Humanities and Social Sciences, United Arab Emirates University, PO Box 15551, Alain, UAE

supports law No. 5 passed in Abu Dhabi to restrict groundwater takes for irrigation to protect the subterranean reserves of water. The coastal soils are protected by mangrove plantation.

19.1

Introduction

The United Arab Emirates (UAE) is a federation of seven emirates (Abu Dhabi, Dubai, Sharjah, Ajman, Umm al-Quwain, Ras al-Khaimah and Fujairah). The capital of the UAE is Abu Dhabi. Abu Dhabi is the largest emirate occupying 84% area of the UAE. The UAE is located between 22°50′ and 26° north latitude and 51° and 56°25′ east longitude at the southeastern tip of the Arabian Peninsula on the Arabian Gulf, bordering Sultanate of Oman to the east and Kingdom of Saudi Arabia (KSA) to the south, as well as sharing sea borders with Qatar and Iran. It shares a 530 kilometer border with KSA on the west, south, and southeast, and a 450 kilometer border with Oman on the southeast and northeast. The total area of the country is about 83,600 km2. The climate of the UAE is subtropical-arid with hot summers and warm winters. The hottest months are July and August, when average maximum temperatures reach above 40 °C. In the Al Hajar Mountains, temperatures are considerably lower, a result of increased elevation. Average minimum temperatures in January and February are 10–14 ° C. During the late summer months, a humid southeastern wind known as Sharqi (“Easterner”) makes the coastal region unpleasant. The average annual rainfall is less than 120 mm, but in some mountainous areas annual rainfall often reaches 350 mm. The UAE is prone to occasional, violent dust storms, which can severely reduce visibility. The Jebel Al-Jais mountain cluster in Ras al-Khaimah has experienced snow only twice since records began. The flora include Prosopis cineraria growing in desert suburbs, the oases grow date palms and acacia trees. In the desert the flora is very sparse and consists of grasses and

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_19

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Fig. 19.1 Coastal landscape enriched with salts through sea water intrusion

S. A. Shahid and T. S. Alsumaiti

possible close to sustainable that ultimately leads to combat desertification in the emirate. The land resources are threatened due to harsh climatic conditions and land degradation. The UAE has taken significant actions to combat desertification to conserve land resources for ecosystem services. The UAE has a different approach relative to other countries on strategies and plans for dealing with desertification based on its environmental conditions (FEA-UAE 2002). The UAE established a National Environmental Strategy (NES) to combat desertification and have set priority areas in its strategic plans in different fields (FEA 2006). Recently the Federal Environment Agency (FEA) has been merged to Ministry of Climate Change and Environment (MOCCE). In this chapter, UAE efforts in soil conservation and compliance of UNCCD to combat desertification are presented.

19.2

Moisture and Temperature Regimes of the Emirate Soils

Biological processes in soil are largely controlled by soil moisture and temperature. Each plant species has its own temperature and moisture requirements. In the UAE soils, Aridic (L. aridus, dry) and Torric (L. torridus, hot) moisture regimes have been identified (Shahid et al. 2014; Soil Survey Staff 2014). Both are same but used in different soil categories of soil taxonomy.

Fig. 19.2 Sandy landscape covering over 75% area of UAE

thorn bushes. The landscape of the UAE ranges from coastal plains and sabkha (Fig. 19.1) to an undulating desert sand plain and sand dunes of various heights (Fig. 19.2), mountainous rock outcrop along the Hajar Mountains, which reach a height of 1925 m at Jebel Al-Jais. During the United Nations Conference on Environment and Development (UNCED 1992) held in Rio de Janeiro 1992, the international community expressed serious concern about the problems of desertification and land degradation. The UNCED adopted, amongst others, Agenda 21, which is a program of action for sustainable development. Agenda 21 is a comprehensive blue print for action to be implemented globally by governments, UN organizations, developing agencies, nongovernmental organizations (NGOs) and independent sector groups. The UAE has joined the UNCCD on 21 October 1998 and became a member on 19 January 1999. The UAE land resources are of high environmental value in which all plants and animals live, clearly there is a lot riding on our capacity to understand, conserve and manage the land resources of the emirate efficiently and as much as

19.2.1 Aridic and Torric (L. Aridus, Dry, and L. Torridus, Hot and Dry) Soil Moisture Regimes These terms are used for the same moisture regime but in different categories of the taxonomy. In the aridic (torric) soil moisture regime, the moisture control section is, in normal years: (1) Dry in all parts for more than half of the cumulative days per year when the soil temperature at a depth of 50 cm below the soil surface is above 5 °C; (2) Moist in some or all parts for less than 90 consecutive days when the soil temperature at a depth of 50 cm below the soil surface is above 8 °C. Soils that have an aridic (torric) soil moisture regime normally occur in areas of arid climates. A few are in areas of semiarid climates and either have physical properties that keep them dry, such as a crusty surface that virtually precludes the infiltration of water, or are on steep slopes where runoff is high. There is little or no leaching in this soil moisture regime, and soluble salts accumulate in the soils if there is a source.

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19.2.2 Hyperthermic is the Soil Temperature Regime Hyperthermic soil temperature regime is identified in the UAE where soils in general present soil temperature as 22 °C or higher, and the difference between mean summer and mean winter soil temperature is more than 6 °C either at a depth of 50 cm from the soil surface or at a densic, lithic or paralithic contact, whichever is shallower (Shahid et al. 2014; Soil Survey Staff 2014).

19.3

275

19.4

Soils of the United Arab Emirates

In recognition to the value of soils in desert environment where temperature is very high and water scarcity is the major issue, the UAE has taken the initiative to assess their soils for soil classification and suitability for various uses (Dubai Municipality 2005; EAD 2009; EAD-MOEW 2012). Based on these soil assessments a unified soil map has been published. This soil map presents ten soil map units based on Great group levels of US Soil Taxonomy (Soil Survey Staff 2014).

Importance of Soils 19.4.1 Aquisalids

Land and soil are the important components of the Emirates desert ecosystem and of the wider environment in which all plants and animals live. Over many years human used environment to gain economic rewards, however, many of the methods used to gain those benefits are now being unsustainable, because in many cases they lead to degrade land “desertification”. All terrestrial life ultimately depends on soil, energy and water. Soils have always been central to human civilization and life and are an integral part of physical and cultural environment that we may take them for granted and even tend to treat them contemptuously. The Emirates landscape is covered mainly by low-lying sandy deserts, extensive coastal salts-flats, alluvial plains and gravelly plains in both the far west and east of the Emirates. The study by Shahid et al. (2004) revealed that, a rather uniform looking coastal landscape in fact, presents a diversity of sub-surface features that help to categorize the soils into different soil classes. The different landscape features suggest the occurrence of soil diversity in terms of classification, chemistry, physics, mineralogy, fertility, suitability for different uses and vulnerability to land degradation etc. Below are facts about soils (Shahid 2007)

These are strongly saline or very strongly saline, poorly drained soils in coastal and inland sabkha. All these soils have salts concentrated in the profile, and some also have a concentration of gypsum. Despite the presence of ground water (within 1 meter from surface), the high salinity makes these soils physiologically dry, limiting the vegetation to salt-tolerant species, or at extreme salinity level these areas are devoid of vegetation. Textures are mostly loamy or sandy. It covers 218,186 ha, or 3% of the UAE. They are considered permanently unsuitable for irrigated agriculture due to near surface saline groundwater and high salt content.

19.4.2 Calcigypsids Calcigypsids have an accumulation of both calcium carbonate (CaCO3) and equivalents (calcic horizon) and gypsum-CaSO4
2H2O (gypsic horizon) within 1 meter from soil surface. Most of these soils are sandy throughout. It covers 14,181 ha, or about 0.2% of the UAE. It has little suitability for irrigated agriculture due to high soil gypsum contents.

Soils are: (1) The essence of life; (2) A product of the environment; (3) Developed, and not merely an accumulation of debris from rocks and organic matter; (4) Different from the material from which they are derived; (5) Continuously changing due to natural and human influences; (6) Different in inherent capability; (7) The sites for chemical reactions and organisms; (8) Medium to support plants; (9) Medium to filter water and recycles wastes; (10) Very fragile; (11) Very slowly renewable.

19.4.3 Haplocalcids Haplocalcids have an accumulation of calcium carbonate (CaCO3) and equivalents within 1 meter from soil surface (calcic horizon). Textures are sandy or loamy. It covers 118,861 ha, or about 1.7% of the UAE. It has moderate potential for irrigated agriculture.

19.4.4 Haplocambids Haplocambids have a loamy subsoil horizon with structure and/or color the form of a cambic horizon. They do not have enough accumulation of calcium carbonate and equivalents

276

(CaCO3) or gypsum (CaSO
2H2O) to have either a calcic or gypsic horizon. Haplocambids are highly suitable for irrigated agriculture.

19.4.5 Haplogypsids Haplogypsids have an accumulation of gypsum within the subsoil. Haplogypsids have sandy textures, but a few are loamy. It covers 71,764 ha, or about 1.0% of the UAE. It has limited suitability for irrigated agriculture due to high gypsum contents and soil depth.

S. A. Shahid and T. S. Alsumaiti

19.4.9 Torriorthents Torriorthents have more than 35%, by volume, gravel throughout. They are on alluvial fans and plains adjacent to the mountains and in wadis within mountain valleys. Other Torriorthents are further from the mountains on alluvial plains or in wadis. They have little or no gravel within the profile. They are mostly sandy but contain one or more layers with loamy textures within 100 cm. It covers 62,123 ha, or about 0.9% of the UAE. It has limited suitability for irrigated agriculture due to gravel content of the soils.

19.4.10 Torripsamments 19.4.6 Haplosalids Haplosalids soils are strongly to very strongly saline soils on flats on deflation or sabkha plains. Haplosalids present salic horizon, and some also have a concentration of gypsum. High salinity makes these soils physiologically dry and limits the vegetation to salt-tolerant species. Textures are mostly loamy or sandy. It covers 381,692 ha, or about 5.4% of the UAE. They are considered permanently unsuitable for irrigated agriculture due to high salt contents.

19.4.7 Petrocalcids Petrocalcids have a subsoil horizon which is cemented (petrocalcic) by the calcium carbonate, forming a hardpan. Petrocalcids are mostly on level to gently sloping landscapes that have been stable for a very long time. Most of these soils are sandy. This map unit covers 2196 ha, or less than 0.1%. It has limited suitability for irrigated agriculture due to depth of hardpan.

19.4.8 Petrogypsids Petrogypsids have a subsoil horizon which is cemented by gypsum (petrogypsids), forming a hardpan. Most of the Petrogypsids are sandy, but a few are loamy. It covers 263,388 ha, or about 3.8% of the UAE. It has little potential for irrigated agriculture due to limited depth of soil to hardpan and soil gypsum content.

Torripsamments are dominated by eolian sands on dunes and sand sheets. These are the most extensive soils in the UAE. They have sandy texture throughout. In order to present their distribution, they are separated into three phases reflecting the landscape relief (height of the dunes). Collectively, the Torripsamments make up 5,261,812 ha, or 75.0% of the UAE. Low relief torripsamments (10 m) make up 2,824,806 ha, or 40.3% of the UAE. They have range of suitability for irrigated agriculture depending on the nature of landform. Low dunes, sand plain and sand sheet are considered moderately suitable and suitability typically declines as the height and frequency increase.

19.5

Indicators of Land Degradation and Desertification

Since the author has started career in UAE back in 2001, he has been working in deserts of the UAE for national soil mapping project and land use planning based on science-based decisions. During the field work he come across many land degradation features to a small and greater extent. The main land degradation component in UAE are, prolonged drought and loose sandy soils “Entisols” consisting of sand sheets and sand dunes of various heights (Fig. 19.2), which are continuously moving across the landscapes based on wind direction and intensity. Awareness about land degradation through field days is a way to witness

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Fig. 19.3 Land degradation and management training session in the UAE deserts

the threats to the deserts (Fig. 19.3). Today’s students are tomorrow’s managers, and the managers the decision makers and land use planners, and therefore awareness will lead them to think ahead to combat multi-faceted land degradation and soil protection for sustainable ecosystem services (Fig. 19.4).

19.6

Evaluation of Soil Movement Mechanisms Through Particle Size Analyses

Among land degradation processes in the UAE wind erosion owing to dominance of sandy soils “Entisols” is seen as the dominant process. Dust storms are commonly seen in the UAE, however, many questions about the evolution of dust storms in the UAE. To answer these questions many soil samples from the deserts of the UAE have been analyzed using Pipette method supplemented by wet sieving to quantify various sub-fractions of sand (very coarse 2–1 mm, coarse 1–0.5 mm, medium 0.5–0.25 mm, fine 0.25–0.1 mm and very fine 0.1– 0.05 mm), and silt (0.05–0.002 mm) and clay (500 µm Saltation 500–63 µm Suspension 500 µm are set in motion by the impact of saltating particles (63–500 µm). The creep sized particles are large and generally cannot be lifted by the wind, and tend to roll and creep on the surface, subsequently lose their sharp edges and become rounded. In Saltation movement the particles (63–500 µm diameter) are rolled on the surface, a vacuum is created at the rear of the moving particles whereas in the front the air is co-pressed below the particles and the particle are lifted in the air (Shahid and Abdelfattah 2008; Fig. 19.6). The lifted particles follow distinct trajectories under the influence of air resistance and gravity. On reaching the soil surface, they may rebound or become embedded when impacting the surface or induce creep and suspension (the raising of fine particles). The saltation particles on reaching the surface can dislodge the soil particles (creep>suspension). The least distribution of particles Table 19.1 Percent distribution of particles in different movement modes

Very coarse sand Coarse sand

19.7

The Major Causes of Soil Erosion and Soil Conservation Practices

Most of the UAE desert environment consists of sandy, sand dune soils which absorb the rainwater due to very high drainage capacity and therefore, no water erosion occurs in these sandy areas. Water erosion is active only during the intensive rainy season, it causes severe runoff flows in the sloppy landscapes and form rills and gullies of various sizes. The high tides erode coastal soils, which are now conserved by mangroves. Wind erosion (loose sandy deserts) is common in the UAE. The UAE has made significant efforts to conserve the soils through multifaceted approaches, such as sand dunes stabilization through afforestation and coastal protection through mangrove establishments. In the inland across the roads and agricultural farms wind breakers have been established by growing date palm trees, conocarpous and zizyphous trees etc. The UAE record of caring for the environment, particularly wildlife has been excellent. In the past many years, to clean and enhance the environmental quality, the wisdom of Late HH Sheikh Zayed Bin Sultan Al Nahyan undertook activities for soil fixation, and to date over 330,000 hectares have been planted (forestry plantation) to stop the creeping of sand, catch suspended particles and clean the environment. In addition, many green belts in the urban and along road sides have been established

0.6%

Creep

3.8%

Saltation

94.3%

Suspension

1.9%

3.2%

Medium sand

13.8%

Fine sand

49.2%

Very fine sand

31.3%

Coarse silt

0.6%

Fine silt

0.2%

Clay

1.1%

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281

Fig. 19.7 Road side plantation to protect roads and reduce sand encroachment

(Fig. 19.7). The implementation of afforestation was considered as preventive measures for some of the desert lands that are not yet degraded, or which are only slightly degraded or prone to be degraded in the emirate. Greening The Desert concept is presenting multiple benefits e.g. halting degradation, promoting sand stabilization and hydrological balance, controling the creeping sand, enhancement of environmental quality, habitat restoration and increase in the aesthetic value of the area.

19.7.1 Coastal Protection Efforts Through Mangrove Establishment The coast being an important ecosystem requires implementation of an integrated coastal area management (ICAM) approach. The ICAM is the accepted framework for long-term planning, use, conservation, and rehabilitation of coastal ecosystems. In this context, mangroves are considered key player in coastline protection, as well as buffer between land and the sea. An increase in storm extreme may cause severe erosion of the mudflats, around which mangroves thrive and subsequent irreversible coastal erosion (Alsumaiti et al. 2017; Alsumaiti and Shahid 2018, 2019). Clearance of coastal mangroves for urban expansion is enhancing the vulnerability of coastal infrastructures to climate change impact like sea level rise, tidal affects and storm surges. Mangroves are considered as carbon sinks because they store and sequester carbon much faster than tropical forests or any other ecosystem on the earth, thus lowers greenhouse

gases (Fig. 19.8). Mangroves like other plants capture CO2 during photosynthesis, thereby removing CO2 from the atmosphere. Mangroves are among the most carbon-rich forests in the tropics (Donato et al. 2011) containing average 1023 Mega-grams carbon per hectare. Mangroves per hectare have the capacity to store carbon four times more than most other tropical forests around the world. Abu Dhabi Emirate is consistently making efforts to increase mangrove plantation. Recently the Environment Agency Abu Dhabi (EAD) partnered with the Tourism Development and Investment Company (TDIC) to plant 750,000 saplings of mangroves on 25% of the Saadiyat Island, which is currently being developed as a cultural hub of Abu Dhabi. The move is aimed at mitigating the environmental damages caused by the massive development on the island (Alsumaiti and Shahid 2018). Mangroves forestation constitutes an important ecosystem. Mangroves and Mangal have two different meanings— mangrove (plant) and mangal (plant community and habitats where mangroves thrive). Abu Dhabi Emirate hosts approximately 110 km2 of both natural and planted mangroves spread along 547 kilometers of shoreline, which provide a rich natural habitat and safe breeding ground for several fish species. Most of the mangroves forests are inaccessible owing to their location; exception is for those in the coast (Rabanal and Beuschel 1978). In addition to the Eastern Lagoon Mangrove National Park of Abu Dhabi that was opened to the public on October 1, 2014, there are vast areas of mangrove forests in Delma, Sir Bani Yas Island, Bu Tinah Island, Saadiyat Island, Abu Al Abyadh Island, Al Aryam Island and the Al Dhabeia islands of Abu Dhabi.

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Fig. 19.8 Coastal soil conservation through mangrove plantation

Only one species of mangrove, Avicennia marina (Forssk.) Vierh. occurs in the Gulf region; other species, Rhizophora mucronate Lam. disappeared in historical times (Alsumaiti et al. 2017).

19.7.2 Land Degradation and United Nations Convention to Combat Desertification (UNCCD) Land degradation is the result of several interrelated factors ending in land that is chemically or physically too degraded for productive use or environmental services, and often also results in degraded visual amenity. The degradation driving forces produce pressures that result in the current state of land resources with a negative impact on society and the environment. The principal desertification processes are degradation of the vegetative cover, accelerated water and wind erosion, and salinization and waterlogging, these processes affect the three major land uses in arid region: irrigated agriculture, rainfed cropping (dry farming), and pastoralism on rangelands (Dregne and Chou 1992). The importance of land degradation among global issues is enhanced because of its impact on world food security and quality of the environment. Soil degradation is a process that lowers the current and/or the potential capability of soil to produce goods or services, or reduction of soil functions or soil uses (Blum 1997). Land degradation encompasses soil degradation and the deterioration of natural landscapes and vegetation. Desertification is a world-wide phenomenon and is a much discussed environmental and social problem, affecting

about one-fifth of the world population, 70% of all drylands and one-quarter of the total land area of the world. The World Map of Desertification (UNEP 1977) shows the UAE in a serious situation where the risk of desertification is high to very high almost all over the country, therefore, land degradation will remain high on the UAE agenda in the 21st century. The principal desertification processes are degradation of the vegetation cover, accelerated water and wind erosion, and salinization and waterlogging, these three processes affect the three major land uses in arid region: irrigation agriculture, rainfed cropping (dry farming), and pastoralism on rangelands. The desertification has been defined by the United Nations Environment Programme (UNEP) as land degradation in arid, semi-arid, and dry sub-humid areas resulting mainly from adverse human impact. This 1991 definition is a revision of the definition formulated at the 1977 United Nations Conference on Desertification. The 1977 definition described desertification as the diminution or destruction of the biological potential of the land, which could lead ultimately to the formation of desert like conditions (UNCOD 1977). The UN General Assembly in 1994 (UN 1994) approved the Convention to Combat Desertification (UNCCD 1994); however, the UNCCD entered into force on 26 December 1996. As of today, the UNCCD has been ratified by 196 states plus the European Union. Currently, all member states of the UN plus the Cook Islands, Niue, and the State of Palestine have ratified the convention. The UAE has joined the UNCCD on 21 October 1998 and became a member on 19 January 1999. The UNCCD defines desertification as land degradation in arid, semi-arid and dry sub-humid areas

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Soil Conservation Practices and Efforts …

resulting from various factors, including climatic variations and human activities (UN 1994); however, it is intensified in the hyper-arid climate as is the case of the UAE. In this definition land includes soil, vegetation and groundwater resources. This definition is in fact modified from an earlier UN version (UN 1992) that stated only the human actions as the causal mechanisms. Gray (1999) stated land degradation as an attribute of human causes, and many relate it to a reduction in productivity. The first world’s soil status report (FAO-ITPS 2015) released in 2015 clearly indicated “the majority of the world’s soil resources are in only fair, poor or very poor conditions, and that conditions are getting worse in far more cases than they are improving”, this is great concern globally and especially the region where loose sandy soils are dominant, water scarcity and prolong drought exists, such as the UAE.

19.7.3 United Arab Emirates Efforts to Comply UNCCD The UAE is located within the arid west continent desert belt, its environment like the other semi-arid and arid environments of the world is very fragile, sensitive and very slowly renewable. The UAE deserts have unique features e.g. vast loose sandy deserts, oasis, long coastline, islands and few mountains etc. Combating desertification is the most spoken and frequently used term in many countries of the world, the UAE looks it from different angles and perspectives based on its environmental conditions and the vision of Late His Highness Sheikh Zayed Bin Sultan Al Nahyan in improving UAE desert conditions; therefore, the term “combating desertification” as a compromise is used as

Fig. 19.9 Greening the deserts —a panoramic view of UAE desert showing agricultural farms and soil conservation practices using wind breakers

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“Greening The Desert” (FEA-UAE 2002). Greening The Desert concerned with converting the natural desert environment into productive agricultural land, conserving its biodiversity and increasing the economic outcome of it. On the other hand, Combating Desertification is the sum of activities leading to integrated development of land (not soil) in arid, semi-arid and sub-humid areas for sustainable development aiming at: prevention and/or reduction of land degradation; rehabilitation of partly degraded land; and reclamation of desertified land. The UAE efforts in Greening The Deserts are very effective; to date over 40,000 agricultural farms are established (Fig. 19.9), 330,000 ha area has been planted through afforestation project in Abu Dhabi Emirate to reduce sand movement and to enhance the environmental quality (Fig. 19.10). The arid forests of Abu Dhabi provide a variety of valuable provisioning, regulating and cultural ecosystem services. Major plantations are of trees, such as, Ghaf (Prosopis cineraria) and Al Sidr (Ziziphus spina-christi) suitable for arid conditions, however, these are irrigated. Saline groundwater is the predominant source for the irrigation water, and current practice is to irrigate Al Ghaf and Al Sidr trees with design quantity of 60 L of groundwater every day of the year. About 95% of the total groundwater consumption is used by agriculture and forestry (EAD 2016), where groundwater is the main natural water-resource in Abu Dhabi. It is mostly a non-renewable resource (Murad et al. 2007; Al Mulla 2011). Groundwater recharge is about 350 Mm3, while the annual abstraction is about 2668 Mm3 (Dawoud 2008). It is estimated that the present groundwater potentiality in both shallow and deep aquifers is about 757.6 km3 of groundwater resources, but less than 7.5% is fresh and, based on current abstraction rates, both fresh and

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Fig. 19.10 Soil conservation through afforestation “Greening The Deserts concept”

brackish reserves will be depleted within 50 years (Abdelfattah et al. 2009). The arid forests of Abu Dhabi consume some 11% of the Emirate’s groundwater. Arid-forest tree species are also used in landscape amenity-plantings and these use some 14% of Abu Dhabi’s groundwater (Al Yamani et al. 2018). Environment Agency Abu Dhabi is the government entity mandated to protect and enhance groundwater resources in the Emirate. Their target by 2020 is to reduce the total volume of groundwater extracted annually from 2.198–1.82 Mm3 (EAD 2016). Over-extraction threatens groundwater resources; therefore, it is essential to conduct research on the optimization of irrigation requirement of afforestation trees in the UAE. Government has allocated funds to monitor the shortage and imbalance of the underground water that will help in future planning of agricultural activities. The current situation, therefore, calls for future establishment of forestry plantation with plants that are deep rooted to extract water from deep soil (without irrigation) and this will lead to sustainability of forestry plantations. To reduce groundwater use by forest trees, recently, Al Yamani et al. (2018) have published a study on the water use of Al Ghaf (Prosopis cineraria) and Al Sidr (Ziziphus spina-christi) forests irrigated with saline groundwater in the hyper-arid deserts of Abu Dhabi. The actual evapotranspiration (ETc) was measured using heat-pulse equipment in the trees. Al Yamani et al. (2018) concluded that with a 25% factor-of-safety, and a 25% salt-leaching requirement, irrigation requirements for Al Ghaf ranged from 24.4 L/d in January to 52.8 L/d in July. For Al Sidr the range was from 33.8 L/d in April to 53.5 L/d in September. These are a 40% saving on current practice. This study supports law No. 5 passed in Abu Dhabi to restrict groundwater taken for irrigation to protect the subterranean reserves of water.

Al Yamani et al. (2019a) further monitored the actual tree water-use (ETc, L/h) via heat-pulse devices in both the GW (EC 8–10 dS/m) and TSE (EC < 1 dS/m) irrigated trees. They quantified the differences in the ETc patterns for both the GW and TSE irrigated trees of both species over 3 years. Both species showed positive growth-responses to TSE, relative to the GW, and they consider this to be due to the lower electrical conductivity of the TSE water. Because of this growth response the ETc of the TSE by the Ghaf trees was, on annual average 17% higher than GW, and for the Sidr it was 39%. These results were corroborated by leaf conductance and leaf-area inferences. But for TSE there is no need for a salt-leaching fraction. Furthermore, to achieve the same tree-health outcome as with the GW, even less TSE needs to be applied. Irrigation requirements for TSE were at least 25% less than for GW. As a follow up a similar study was conducted (Al Yamani et al. 2019b) on Al Samr (Acacia tortillis) forest irrigated with saline and treated sewage effluent (TSE) in the hyper-arid deserts of Abu Dhabi. In this study tree water use was measured using sap flow monitoring of GW-irrigated trees, and trees irrigated with TSE. Maximum rates of tree water-use, ETc, were found to be around 10 L/d, and there are two distinct deciduous periods where ETc briefly dropped below 2 L/d. The total annual water use of the TSE-irrigated trees was 2.2 kL/a, which is about 25% higher than the 1.8 kL/a for the GW-irrigated trees. For Law 5, it was recommend that the irrigation allocation for Al Samr trees be simply based on a constant ETc of 10 L/d. So for GW irrigation, allowing for a 25% factor-of-safety, and a 25% salt-leaching fraction, the recommended allocation would be 15 L/d. This represents a saving of 75% from the current practice of irrigation 60 L/d. For TSE, without the need for salt leaching, the irrigation allocation would only need to be 12.5 L/d.

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285

The achievements and success stories of Greening The (13) Afforestation of 330,000 ha area in Abu Dhabi Emirate. Desert concept would not have been possible without wise policies and urgency that Late His Highness Sheikh Zayed (14) Increase in Agricultural areas etc. Bin Sultan Al Nahyan had placed on dealing with the environmental issues. His Highness highlighted this interest in his message to the Earth Summit in 1992. Following are the major achievements and activities towards Greening The 19.8 Conclusions and Recommendations Desert of UAE (FEA-UAE 2002; Shahid 2007). The United Arab Emirates is in drylands, where drought is (1) Authorization of Federal Environmental Agency common; soils are mainly sandy; all these factors cause (FEA) as functional national coordination body in the severe land degradation. To achieve maximum benefits from UAE for the UNCCD. Currently FEA is absorbed by the fragile ecosystem, it is essential to take actions to halt UAE Ministry of Climate Change and Environment degradation and conserve natural resources. Considering the importance of UAE natural resources significant efforts have (MOCCE). (2) National Environmental Strategy and the National been made, such as but not necessarily limited to, increase of Action Plan—The FEA prepared the strategy and agricultural farms, afforestation of over 330,000 ha to comaction plan and they were adopted in 2002 in the ply UNCCD in the form of “Greening The Desert” concept to context of the national policies for conservation and control sand encroachment, fix sandy soils and to protect the sustainable use of natural resources, combating deser- environment. The law 5 passed in Abu Dhabi restricts tification and fulfilling the commitments of Agenda 21. groundwater takes for irrigation to protect the subterranean (3) Completion of detailed Strategies and National Action reserves of water. Though, the plantations are irrigating, efforts have been made to optimize irrigation requirement of Plan to Combat Desertification in the UAE. (4) Scientific and technological activities resulting in forest trees to reduce 30–40% irrigation water. It is recommended to expand afforestation in areas where greening deserts i.e. afforestation, planning nutritious productions for human being and animal feed, as well water table is high and the trees take water from high water table and do not require irrigation and hence afforestation as opening of scientific centers. (5) Completion of the state-of-the-art soil surveys of Dubai becomes sustainable. Combat desertification efforts in UAE emirate (DM 2005), Abu Dhabi emirate (EAD 2009) are taking significant resources, and the benefits from these and northern emirates (EAD-MOEW 2012) for science efforts are yet to be quantified to keep the balance between investment and returns. Sand dunes need to be stabilized based informed decisions. (6) Opening of Emirates Soil Museum in 2016 at the Dubai through improving natural vegetation, controlled grazing based International Center for Biosaline Agriculture and deserts rehabilitation. Awareness on land degradation (ICBA) for soil education to potential stakeholders for and combating desertification to be raised to multi stakeholders to respect the environment for prolonged ecosystem national development and environmental protection. (7) Preparation of a national project for the assessment of services. affected agricultural lands for sustainable use (Shahid 2004). The project was approved by the National Acknowledgements We would like to thank John A. Kelley, USDA Soil Scientist and Regional Correlator in the eastern USA (retired) and Committee on the Environmental Strategies—UAE. who had served as Quality Assurance Specialist for the Soil Survey of (8) Establishment of Abu Dhabi Global Environment Data Abu Dhabi Emirate, for sharing the images used in Figs. 19.1, 19.7, Initiative (AGEDI) by Environmental Agency-Abu 19.9, 19.10. Dhabi. (9) Formation of National Committee for the Follow up of UNCCD. References (10) The legal and legislative frame-work for protection of the environment-Law number 24. Federal Law Abdelfattah MA, Dawoud MAH, Shahid SA (2009) Soil and water No. 24 of 1999 on the environment protection and management for combating desertification-towards implementation of the United Nations Convention to Combat Desertification from development. the UAE. In: Proceedings international conference soil degradation, (11) Establishment of International Center for Biosaline Riga, pp 35–45 Agriculture (ICBA) Dubai in 1999 with partial support Al Mulla M (2011) UAE state of water report. Ministry of Environment from the Government of the UAE and Islamic Develand Water, Abu Dhabi, United Arab Emirates Al Yamani W, Green S, Pangilinan R et al (2018) Water use of Al Ghaf opment Bank Jeddah Saudi Arabia. (Prosopis cineraria) and Al Sidr (Ziziphus spina-christi) forests (12) Implementation of “Desert Greening Projects”.

286 irrigated with saline groundwater in the hyper-arid deserts of Abu Dhabi. Agric Water Manag 203:105–114 Al Yamani W, Green S, Pangilinan R et al (2019) Water use of Al Samr (Acacia tortilis) forests irrigated with saline groundwater and treated sewage effluent in the hyper-arid deserts of Abu Dhabi. Agric Water Manag 216:361–364 Al Yamani W, Green S, Pangilinan R et al (2019) The impact of replacing groundwater by treated sewage effluent on the irrigation requirements of Al Ghaf (Prosopis cineraria) and Al Sidr (Ziziphus spina-christi) forests in the hyper-arid deserts of Abu Dhabi. Agric Water Manag 214:28–37 Alsumaiti TS, Shahid SA (2018) A comprehensive analysis of mangrove soil in eastern lagoon national park of Abu Dhabi Emirate. Int J Bus Appl Soc Sci 4(5):39–56 Alsumaiti TS, Shahid SA (2019) Mangroves among most carbon-rich ecosystem living in hostile saline rich environment and mitigating climate change—a case of Abu Dhabi. J Agric Crop Res 7(1):1–8 Alsumaiti TS, Khalid H, Alsumaiti AS (2017) Mangrove of Abu Dhabi Emirate, UAE, in a Global Context: A review. Int J Environ Sci 6 (4):110–121 Bagnold RA (1973) The physics of blown sand and desert dunes, 5th edn. Chapman and Hall, London Blum WEH (1997) Basic concepts: degradation, resilience and rehabilitation. In: Lal R, Blum WEH, Valentin C, Stewart BA (eds) Methods for assessment of soil degradation. Advances in soil science series. CRC Press, New York, pp 1–16 Dawoud M (2008) Abu Dhabi water sector paper. Environment Agency-Abu Dhabi (EAD), Abu Dhabi, UAE Donato DC, Kauffman JB, Murdiyarso D et al (2011) Mangroves among the most carbon-rich forests in the tropics. Nat Geosci 4:293–297. https://doi.org/10.1038/ngeo1123 Dregne HE, Chou NT (1992) Global desertification dimensions and costs. In: Degradation and restoration of arid lands. Texas Tech University, Lubbock Dubai Municipality (DM) (2005) Satellite imagery and thematic mapping project. Dubai Municipality, Al Rigga, p 221 EAD (2009) Soil survey of Abu Dhabi emirate, vol 5. Environment Agency Abu Dhabi, United Arab Emirates EAD (2016) Strategic plan 2016–2020. Environment Agency Abu Dhabi, United Arab Emirates EAD-MOEW (2012) Soil survey of Northern Emirates, vol 3. Environment Agency Abu Dhabi, United Arab Emirates FAO-ITPS (2015) Status of the world’s soil resources. Main report. Food and Agriculture Organization of the United Nations and Intergovernmental Panel on Soils, Rome, Italy FEA (2006) United Arab Emirates’ 3rd National Report on Implementation of the United Nations Convention to Combat Desertification. Federal Environment Agency, United Arab Emirates FEA-UAE (2002) Summary of the United Arab Emirates’ 2nd National Report on Implementation of the United Nations Convention to Combat Desertification. Federal Environment Agency, United Arab Emirates\ Gray LC (1999) Is land being degraded? A multi-scale investigation of landscape change in southwestern Burkina Faso. Land Degrad Dev 10:329–343

S. A. Shahid and T. S. Alsumaiti Murad AA, Al Nuaimi H, Al Hammadi M (2007) Comprehensive assessment of water resources. Water Resour Manag 21:1449–1463 Rabanal HR, Beuschel GK (1978) The mangroves and related coastal fishery resources in the United Arab Emirates. FAO, Rome Shahid SA, Omar SAS, Al-Ghawas S (1999) Indicators of desertification in Kuwait and their possible management. Desertification Control Bull 34:61–66 Shahid SA, Abdelfattah MA, Wilson MA et al (2014) United Arab Emirates keys to soil taxonomy. Springer, Dordrecht Shahid SA, Abdelfattah MA (2008) Soils of Abu Dhabi Emirate. In: Perry RJ (ed) Terrestrial Environment of Abu Dhabi. Environment Agency-Abu Dhabi, Abu Dhabi, UAE, pp 71–91 Shahid SA, Omar SAS (2001) Causes and impacts of land degradation in the arid environment of Kuwait. In: Bridges EM, et al (eds) Response to land degradation. pp 76–77 Shahid SA, Omar SAS, Al-Ghawas S (2001) Evaluation of aeolian soil movement mechanisms as a function of particle size analysis. KISR Annual Report No 5851, pp 37–40 Shahid SA, Omar SAS, Misak R, et al (2003) Land resources stresses and degradation in the arid environment of Kuwait. In: Alsharhan AS, Wood WW, Goudie AS, Fowler A, Abdellatif EM (eds) Desertification in the third millenium. Swets and Zeitlinger Publishers, Lisse, pp 351–360 Shahid SA, Abdelfattah MA, Arshad KR, et al (2004) Soil survey for the coastline of Abu Dhabi Emirate. 2 Volumes (Volume 1: Reconnaissance Survey and Volume 2: Soil Maps). Unpublished Report of the Environmental Research and Wildlife Development Agency, Abu Dhabi, UAE Shahid SA (2004) National project for the assessment of affected agricultural lands for sustainable use. In: Proposal submitted by Ministry of Agriculture and Fisheries of the UAE to the National Committee on Environmental Strategies, UAE Shahid SA (2007) Soils. In: Physical geography sector paper. Abu Dhabi Global Environment Data Initiative AGEDI, Environment Agency Abu Dhabi, pp 5–41 Soil Survey Staff (2014) Keys to soil taxonomy, 12th edn. USDA-NRCS, Washington DC UN (1992) Report on UNCED, Malaysia draft resolution. UN General Assembly 47th session, second committee agenda item 79, 20 November UN (1994) Convention of desertification. Information programme on sustainable development. UN, New York UNCCD (1994) United Nations Convention to Combat Desertification, Adopted 17 June 1994 in Paris, France, United Nations, New York, NY, USA. http://www.fao.org/desertification/article_html/en/1.htm. 2008-12-11 UNCED (1992) Agenda 21: programme of action for sustainable development, Ch 12. In: United Nations conference for environment and development. UN Publication, New York, N. Y., Section 2, pp 98–108 UNCOD (1977) Round-up, plan of action and resolutions. In: United Nations conference on desertification, Nairobi, Kenya, p 43 UNEP (1977) World map of desertification. A/CONF. 74/2. UN, New York

Land Degradation in Iran

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Seyed Hamidreza Sadeghi and Zeinab Hazbavi

20.1

An Introduction to General Situation of Iran

The Islamic Republic of Iran is in the southwest of Asia and Middle East with an area of 1,873,959 km2 (Nami 2013; Sadeghi and Hazbavi 2015; Fig. 20.1) and total population of 80,277,428 (databank.worldbank.org/). Iran includes 31 provinces with annual temperature ranging from −20 to +40°C (Amiraslani and Dragovich 2011). It lies between 25° and 40° N latitude and 44°–63° E longitude. Iran locates in arid and semi-arid part of the world, which made it as one of the most vulnerable regions in the world to climate change (Azari et al. 2013; Sadeghi and Hazbavi 2015). The elevation varies from −40 to 5670 m, which has pronounced influence in the diversity of the climate (Ramezani et al. 2013). The lowest point of Iran internal flats is located in the Kalut area, being only 185 meters above the mean sea level (Yazdi et al. 2014) where has been recorded as the hottest place on the earth (approximately 70.7°C) (Solouti and Babaniavardi 2011; Yazdi et al. 2014). According to land use and cover map of Iran; deserts, rangelands, agricultural lands, forests, and residential areas cover almost 20%, 55%, 11%, 8%, and 6% respectively (Iran Forest, Range and Watershed Management Organization, Hosseini 2003; FRWO 2005). Another view of land use distribution in Iran, which reported by Millennium Ecosystems Assessment (MEA 2017) has also been depicted in Fig. 20.2. Iran is bounded by two mountain ranges, i.e. Alborz (Elburz) in the north and Zagros in the west and extended to S. H. Sadeghi (&) Department of Watershed Management Engineering, Iran and President of Watershed Management Society of Iran, Tarbiat Modares University, Tehran, Iran e-mail: [email protected] Z. Hazbavi Member of Water Management Research Institute, Department of Natural Resources, Lran and Chair of Student Committee of Watershed Management Society of Iran, University of Mohaghegh Ardabili, Ardabil, Tehran, Iran

the south (Fig. 20.1). These mountains ranges avoid Mediterranean moisture-bearing systems via crossing through the region to the east. The central Alborz runs from west to east along the entire southern coast of the Caspian Sea, whereas the eastern Alborz runs in a northeasterly direction towards the northern parts of the Khorasan region southeast of the Caspian Sea. Damavand Mountain, is the highest mountain in Iran and situated in the central Alborz Mountain Range. The Zagros Mountain Range is in authority for the major portion of the rain-producing air masses, which enter the region from the west and northwest, with relatively high rainfall quantities for those areas (Sadeghi et al. 2002; Bari Abarghouei et al. 2011; Sadeghi and Hazbavi 2015). These mountain ranges have the most important role in spatio-temporal distribution of precipitation, so that the northern and western Iran have sub-humid and Mediterranean climates and are richer in terms of water availability and precipitation. While, semi-arid to hyper arid climates are dominant in central Iran. The mentioned areas have a continental climate with cold winters and hot summers, where the annual mean temperatures vary between 22 °C and 26 °C. While, in some areas of the country, the temperature goes beyond 50°C in the summer (i.e. July and August). Additionally, hydrogeological conditions are heterogeneous across the country (FRWO 2005). In the eastern and southern Iran, water scarcity is critical due to inadequate precipitation, high temperature, and improper management of water resources (Dinpashoh et al. 2004; Asadi Zarch et al. 2011). The precipitation has an important role in characterizing the climatic spatio-temporal variations in the country (Dinpashoh et al. 2004; Asadi Zarch et al. 2011). In the south, summers are very hot and the winters are mild. The rainy period, in the most parts begins in November and ends in May, and the dry status prevails in the other months. In the northwest, winters stand cold with heavy snowfall and sub- freezing temperatures throughout December and January. Autumn and spring are relatively mild, while summers are hot and dry (Sadeghi et al.

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_20

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Fig. 20.1 General view of Iran and its location in the world and Asia. Source Yazdi et al. (2014) (b)

evapotranspiration reach up to 284
109 m3, representing the 71% of the total annual mean precipitation of the country (Asadi Zarch et al. 2011).

20.2

Nature of Main Soil and Water Resources Issues in Iran

Increasing land degradation in Iran has become a serious problem threatening soil and water resources (Sadeghi et al. 2004; Behzadfar et al. 2015). During the last four decades, the natural resources of Iran have faced some serious degradation problems such as soil erosion, sedimentation, wind erosion, water scarcity and pollution, groundwater overexploitation, land use changes, overgrazing in the rangelands, soil salinity, forest fire, flooding and wetlands loss. More explanation and information for each land degradation type in Iran has been given in the following.

Fig. 20.2 Land use pattern in Iran (MEA 2017)

20.2.1 Erosion and Sediment-Related Issues

2002). The annual mean precipitation in Iran has been recorded at around 240 mm. However, this amount reaches about 1800 mm somewhere at the Caspian coasts and the Alborz Mountain Range with 480 mm in the Zagros Mountain Range. The above explained precipitation quantities decline below 100 mm in the central and interior plains of Iran (Dinpashoh et al. 2004). The mountainous watersheds and plains are 53 and 47% of the total territory, respectively. Based on the statistics of Ministry of Energy, the annual mean precipitation is estimated to be some 400
109 m3, of which 310
109 m3 happens on the mountainous regions and 90
109 m3 on the plains. In the mountainous areas, the annual mean rates of

Land degradation caused by soil erosion is very serious in Iran (Sadeghi et al. 2004; Sarmadian et al. 2010; Behzadfar et al. 2015; Hosseini and Ashraf 2015) and stands in the first priority. In some parts, it is importantly influenced by land use and management (Sadeghi et al. 2004). Additionally, this might be due to changes in potential erosive driving forces or erodible conditions (Sadeghi and Hazbavi 2015). In addition, in agricultural systems soil erosion is a very important problem to manage. Totally, soil eroded away by two important agents of water and wind. Water erosion generally occurs on slope areas, and its severity increases with the severity of the slope. The most evident form of water erosion is reported as gully erosion. It is a major

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source of sediment in arid and semi-arid watersheds in Iran and is the most visible and the most widespread factor of soil degradation in Iran (Vaezi et al. 2016). Gully erosion constitutes a major problem in natural resources management and soil conservation, which causes severe land degradation in arid and semi-arid areas (Tahmasebipour et al. 2016). Of course, some regional projects and even a nation-wide project have been presently accomplished by authorities i.e., Soil Conservation and Watershed Management Research Institute (SCWMRI) of Iran. Loose soils from flat or hilly terrain can be blow away by high winds. According to Eskandarie (2012), much of the wind erosion in the mid-west and northern Iran happens in winter. Because in the winter the ground is frozen and upper most layers of the soil are dry and loose. Besides that, water erosion is more serious in spring due to the snow thawing and melting cycles in the soil. Some examples of different types of soil erosion in Iran have been shown in Fig. 20.3. Million ha of Iran areas are recently influenced by wind erosion processes, due to special environmental conditions,

Fig. 20.3 Some views of soil erosion types in Iran

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such as rainfalls being less than 150 mm, lack of vegetation, and strong and long lasted winds. These factors have caused the influx of quicksand into infrastructures, settlements, communication ways and industrial and agricultural installations. This problem is considered as one of the most important environmental issues in some parts of Iran. Wind erosion and running sand influx pose in the event of a serious indicator of desertification and serious threat for arid areas. The running sand influx makes much damage to towns and villages, streets, roads, and also the loss of soil fertility (Refahi 2015; Yamani and Arabameri 2015). Sand hills, Barchans, Yardangs, Nebkas, Rebdous, Kaluts, Camel-Foot Plains (Dasht-e-Pashotori), Salt Lands, Shoor Rivers and Gandom Beryan hill are some examples of desert and semi-desert current landscapes created due to wind erosion in Iran (Yazdi et al. 2014; Yamani and Arabameri 2015). Some views of wind erosion features created problems and structures are presented in Fig. 20.4. Soil loss and sediment load in Iran may have great implications for water productivity and food security as well

290

Fig. 20.4 General view of wind erosion created issue in Iran (Emadodin et al. 2012)

as water resources development (Azari et al. 2013). Iran, as one of the progressing countries, currently faces many sediment-related problems. High potential sensitivity of resources, improper and unnecessary infrastructures development, land use changes and unlawful exploitation of resources all are supposed as main reasons behind irregularities in ever-increasing sediment yield. However, inattention to soil value, limited numbers of hydrometry stations, short-term data collection period, unreliable and opponent data and information, misunderstanding of the sediment yield processes and people’s and experts’ apathies mask the severity and intensity of the problem (Sadeghi 2009).

20.2.2 Water Issues Iran as a country with severe water stress is located in the critical region of Middle East, faced the worrying prospect, that if do not set the correct management and favorable domestic and international policies for the future, environmental crises, political, social, economic and even military-security inside and outside the political boundaries will be expected. Aspects and consequences of the crisis could challenge the country independence and territorial integrity. Therefore, it is essential to recognize the consequences and how to manage them (Madani 2014; Rezayan and Rezayan 2016). Totally, two mechanisms of inadequate natural water supply resources and development of water infrastructures are the main reasons of water scarcity in Iran. A wide range of long-standing concerns and emerging pressures due to the changing of socio- economy, population growth and climatic situation, the current state of water security on country-wide scales will also be continued. Due to a number of recent environmental catastrophes across the country like critical conditions of lakes and aquatic ecosystems, the severe

S. H. Sadeghi and Z. Hazbavi

decline in groundwater storage and the translation of middle-intensity rainfall events to deadly floods, the creeping effects of water insecurity in Iran have started to be noticed, not only by experts but also by the general public (Nazemi 2016). Indeed, over all, Iran has been a water-scarce country with substantial spatio-temporal differences in hydroclimatology, population and socio-economy. So, strict policies for optimal water resource management are required (Nazemi 2016). The effects of dam construction in Iran seem to be very undesirable. It caused significant shrinkage in water ecosystems, reductions in access to downstream waters, deterioration of upstream and downstream water quality, land salinization and desertification like many other parts of the world (Lehane 2014). Dam reservoirs supply water resources for drinking, agriculture, and industry almost in all parts of Iran. The lack of proper utilization rules and unbalanced demands versus available water has led to many problems regarding to ineffective use of the water resources (Kaki et al. 2016). An example of the mentioned problem, which threatened Zayandehrood Watershed has also been shown in Fig. 20.5.

20.2.3 Land Use Change Almost 510,000 km2 (29%) land of Iran is allotted to the agriculture as one of the most important economic sectors. Since very large population is economically reliant on agriculture, it has been extensively extended (Hosseini and Ashraf 2015). Deforestation in Iran has become more rapid in the past half century than at any time in Iran history. Intensive cultivation and mismanagement have caused environmental problems and soil degradation (Bahrami et al. 2010; Hosseini and Ashraf 2015). Soils, which developed under natural forests in northern Iran have also been disrupted by land use changes (Bahrami et al. 2010).

20.2.4 Overgrazing It is widely recognized that Iranian rangelands are overgrazed as shown in Fig. 20.6. Overgrazing is characterized by the removal or destruction of too much biomass causing a decrease in soil organic matter content and soil biological activity (Stroosnijder 1996; Engels 2002; Sadeghi et al. 2008). The area of relinquished cultivable land in Iran has doubled in recent years and the amount of livestock on rangeland is estimated to be two to three times of the carrying capacity (NRCE 1992). These scientific challenges are exacerbated by Iran’s population growth, inefficient water and land management and penchant for “quick-and-easy” development. Since the

20

Land Degradation in Iran

291

Fig. 20.5 A general view of the Zayandehrood Dam (Upper left) and consequent desertification (Jafari and Hasheminasab 2017)

20.2.5 Soil Salinity

Fig. 20.6 Overgrazing exacerbates desertification (www.permaculturenews.org)

late 1970s, the population of Iran has increased more than twofold. These complexities are considerably more noticeable in Iran in results of semi-arid climate, large heterogeneity of natural and human water systems, inadequate data availability and special conditions within the socio- economic and cultural narratives leading to very complex responses in natural and anthropogenic water bodies (Nazemi 2016).

In majority of dry land areas of Iran, since all irrigation water contains salt, irrigation is known to be a major driver for salinization. When cropland is irrigated and water evaporates, salt is left behind. If there is no drainage, salinity increases until the land becomes unproductive and ultimately forced to be abandoned. Salt affected soils are widespread in the country. In central Iran, particularly where salinity is one of the main factors threatening sustained food production is a very concerned issue. Soils with high salinity (EC = 16–32 dS/m) has been estimated with an area of 8.5 million ha and slightly to moderately (EC = 4–16 dS/m) salt-affected soils cover 25.5 million ha of Iranian territory (FAO 2000; Qureshi et al. 2007). A scene of salt affected land in the Urmia Lake has been demonstrated in Fig. 20.7.

20.2.6 Forest Fire Annually, several pasture fires happen in Iran that strongly affect the sparse vegetative resources. The losses caused by forest fires are estimated to be equal to the total area of reforestation. Most fires are initiated by arson activities. Land use change, inattention of hunters and pickers, and oil smuggling are considered other causes of forest fire in Iran

292

S. H. Sadeghi and Z. Hazbavi

Fig. 20.7 The Urmia Lake in the north west of Iran turning to salt land (www.watchers.news)

Fig. 20.8 Wildfire in the Zagros Forest (www.theiranproject.com)

(Alexandrian and Esnault 1998). At first pasture land and then sparse forests are main subjected areas to fire. Fires that start in or around forests are usually surface fires and only seldom crown fires; among them, fires in coniferous forests are most significant (World Bank 2005). In Fig. 20.8, a view of fire, which happened in the Zagros Forest in 2016 has been shown. Fig. 20.9 A view of heavy flood events in Feb 2017 in southern Iran (www.tehrantimes.com)

20.2.7 Flooding Most of streams in Iran are seasonal. They are dry in summer and cause flooding during spring. These lead to noteworthy variability in freshwater accessibility for those reliant on surface water resources. Flooding has increased in the last decades. Bad land use management and deforestation contributed to the floods frequency and intensity in Iran. An unusually rainy period can trigger more flooding due to changes in land use. Iran forests have been severely degraded over the last decades. Vegetative cover also is another

major factor influencing the degree of floods (World Bank 2005). Over the last 57 years, forest clearing for apiculture, firewood and charcoal production reduced forest area from 19.5 to 12.4 million ha. Due to the high level of vulnerability of southern coastal strip of the Caspian Sea, river flooding is known as common natural disaster and is of great concern there (Sadeghi-Pouya et al. 2017). In Fig. 20.9, views of floods occurred in 2017 in Bushehr and Fars Provinces, southern Iran are presented.

20

Land Degradation in Iran

20.2.8 Wetland Loss Wet lands are one of the most important ecosystems on the Earth. Nevertheless, various challenges threaten these ecosystems and disrupt their ecological character (Daryadel and Farhad 2014). There are considerable number of wetlands in the Islamic Republic of Iran. However, many of wetlands in Iran are suffering from adverse effects of different activities, which adversely affect nature, economy, health, food and tourism (National Wetland Conservation Strategy and Action Plan 2011). Among Iranian w etlands, 84 have been recognized as of international importance and 24 are listed in the Ramsar Convention signed in Ramsar, Iran in 1971. There are more than 1800 Ramsar sites around the world and Iran is ranked as the 19th country among 150 members of the Convention for the number of designated wetlands. Unfortunately, as a result of drought, mismanagement, and reduction of water inflows considerable number of Iranian wetlands have been degraded in recent years. This situation has led to degraded biodiversity and a reduction of ecological functions, which in turn has caused socio- economic damage (National Wetland Conservation Strategy and Action Plan 2011). A picture of one of the most important wetlands in Iran known as Hamoun Wetland in southeastern Iran has been shown in Fig. 20.10. Due to drying up this wetland, many households became poor and migrated from Sistan and Baluchestan Province to other regions of Iran.

293

20.3

Magnitude of Main Soil and Water Resources Issues in Iran

20.3.1 Magnitude of Erosion and Sediment-Related Issues Even if Iran faces a severe water erosion phenomenon, the lack of hydrometric and sedimentation stations creates difficulties for estimating its rate at watershed level (Fathizad et al. 2014). Of which 2%, 15% and 26% of the country area are influenced by strong erosion, moderate and light erosion (World Bank 2005). Because of climate and topographic conditions of Iran, some 75 million ha are threatened by water erosion (Asadi et al. 2012). The average national rate of water erosion has been reported 15-45 t/(haa) [Ministry of Jihad and Agriculture (MoJA) 2004; Amiraslani and Dragovich 2011; Felegari et al. 2014; Moghadam et al. 2015; Zare Garizi and Talebi 2016) and is mainly due to inadequate agricultural land use (Amiri 2010). About 94% of arable lands and permanent rangelands are in the process of degradation by soil erosion [FAO/United Nations Environment Program (UNEP) 1994; Masoudi et al. 2006]. Land use changes mostly from rangeland to dry farming, has led to an 800% increase in soil erosion between 1951 and 2002 (Ahmadi 2011; Nosrati et al. 2011). Since more than two-thirds of the land surface of Iran can be classified to be arid to semi-arid, water erosion is a serious problem in many watersheds with specific sediment

Fig. 20.10 The Hamoun Wetland degradation (www.financialtribune.com)

294

yield rates ranging from 8 t/(haa) to 16 t/(haa) (Mahdian 2005). In terms of water erosion, Iranian soils are under a serious risk due to hilly topography, low organic matter, poor plant coverage, and inappropriate agricultural practices like excessive soil tillage and cultivation of steep lands (Arekhi et al. 2012). In Iran, it is estimated that the average annual erosion rate of watershed is more than 20 times of acceptable average level in the world (Jalalian et al. 1997). However, soil loss in Iran has increased tremendously from 0.5 to 2.2 billion t/a for the period of 1950–1990. It shows an increase of more than four folds during four decades. Overgrazing, dry farming, deforestation, land use change, and improper cultivation practices are the major causes of watershed degradation in Iran (Jalalian et al. 1997; Heshmati 2010; Vaezi et al. 2016). Based on available documents, it can be calculated that the amount of sediment in last 40 years has increased from 500 million t/a of soil (Nakhjavani 1976) to 2 billion t/a (Arabkhedri 2005) and according to some statistics, about 3.5 billion t/a has been carried away (Felegari et al. 2014). Iran has more than 10 million ha of cultivated land under irrigation and more than eight million ha of agriculture land under dry farming (Iran daily 2000; Safamanesh et al. 2006). Drylands cover more than 85% of Iran and are very prone to desertification (Jafari and Hasheminasab 2017). It is estimated that 35.4 million ha are under the influence of wind erosion (Lal 1999). Sand dunes as an indicator of desert land cover an area about 32 million ha, among which 12 million ha has not been stabilized yet. Advancing moving sand dunes has resulted in much damage to agricultural products and urban areas (Moradi et al. 2008). According to the Bureau of Desert Affairs of Iran, 17 provinces have desert areas, which are home to approximately 70% of the total population of the country, and about 20% of these regions have been influenced by desertification processes (Jafari and Hasheminasab 2017). Studies have shown that a wide range of Iran continent experiences wind erosion (Ahmadi and Shighanpoor 2010). A severe dust storm in Tehran, capital of Iran, strongly reduced air quality and attracted public attention to wind erosion problems in Iran. A study shows that 48,219 ha in Sistan Region in eastern Iran is covered by wind erosion, with another 19,577 ha susceptible when poor management and unfavorable weather conditions are combined. In Iran, the average monthly wind speed is the highest in October– December. The average wind speed reaches the maximum in December, and the number of days on which the maximum wind speed is over 10 m/s and also the highest in this month. Therefore, October-December is the most important months in viewpoint of wind erosion (Mirmousavi 2016). The spatial distribution of the number of days in October to December with a maximum wind speed higher 10 m/s in the

S. H. Sadeghi and Z. Hazbavi

period of 1970–2012 varies by regions in northwest and southwestern Iran. The number of days ranges from 15 to 27 days. The highest wind erosion risk was identified in Khuzestan Province and some parts of western provinces due to the sandy soils in these areas. Similarly, a high sensitivity was detected in southwestern of study area where the soil is mainly loess and loam and also more frequent and stronger winds contributed to the high sensitivity. Two critical factors affecting soil erosion include the intensive agriculture in southwestern Iran (mainly with wheat and sugarcane production) and the non-vegetated soils during the autumn months, when the wind erosion risk is the highest (Mirmousavi 2016).

20.3.2 Magnitude of Water Issues In Iran, the main source of water is precipitation, which normally amounts to 251 mm or 413 billion m3, annually. Annual rainfall ranges from less than 50 mm in the deserts to more than 1600 mm on some parts of the Caspian Plain. Overall, about two-thirds of the country receives less than 250 mm of rainfall per year. More than 50% of the rainfalls in winter and a few amount of precipitation occurs in summer. While, 1% of the world population lives in Iran, the share of renewable freshwater is only 0.36% (Malekinezhad 2009; Kousari et al. 2014). Approximately, 37 million Iranian inhabitants are susceptible to food and water scarcity (Raziei et al. 2009). The Iranian Emergency Agency reported that 278 cities and 1050 villages had been influenced by severe drought in Iran. While, four and 2.7 million ha of the crops of rainfed and irrigated regions have been entirely damaged by the drought of 1998–2001. The total agricultural and livestock loss was assessed to be US$2.6 billion by the year 2001 (Shahabfar and Eitzinger 2008; Asadi Zarch et al. 2011). Iran has 151 dams in operation with a capacity of 25 billion m3. More than 90% of this water i.e., 23 billion m3 was estimated under irrigation use (World Bank 2005). Water from storage and diversion dams is used to irrigate 22% of total irrigated areas (i.e. 1.6 million of 7.4 million ha). The watershed areas of dams under operation are estimated some 10.6 million ha (Ministry of Energy Databank 2003). In view of dam building Iran is now placed third, globally. There are more than 500 dams presently operating, with approximately 100 more under construction and 400 in the design stages. Iran FRWO reported in mid-2013 that more than two-thirds of Iran land is rapidly turning into desert. As ground water tables drop, salt- water intrusion is influencing irrigation water and leading to greater soil salinity. This is a double-edged sword; irrigated systems result in greater crop yields and this has encouraged planners and policy makers to focus on the expansion of irrigation

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295

through dams and associated infrastructure. According to the Soil and Water Research Institute of Iran (SWRI), however, the increased salinity has led to patchy crop stand, retarded growth and even leaf burn in areas where poor quality water has been sprayed (Lehane 2014).

20.3.3 Magnitude of Land Use Change During the early years after the Islamic revolution of Iran (1979) and occurrence of the imposed war against Iran (1989-1981), extensive migrations started all over the country. Many farmers came to cities progressively because of economic stagnation in villages resulted from land reform and waning of seasonal economy. Besides farmers’ migrations, there were widespread migrations from towns to large cities, mainly to the capitals of provinces. According to these conditions and upon evaluating the trends, it is predicted by demographers that the population in cities will be doubled during the next 20 years (Yaghoubkhani 2012). Land use changes in Iran have been more rapid in the past half century than at any time in Iran history and are expected to accelerate in the next years (Emadodin 2008). With a rapidly increasing population and a strong rise of the living standards, the necessity to intensify agricultural production increased; this situation puts pressure on other resources. The natural forests in Iran consequently reduced from 19 million ha in the 1950s to 12.4 million ha in the 1990s. During the past 50 years, the area of cultivated land in Iran has grown by more than five times, increasing from 2.6 million ha to 24.5 million ha (Bahrami et al. 2010).

20.3.4 Magnitude of Overgrazing Vegetation covers of rangelands and forests have been negatively impressed by overgrazing during the last decades across Iran (Asadi et al. 2017). A key feature in rangeland degradation is plant cover loss due to overgrazing, allowing increased erosion and salinization processes to occur (Raiesi 2017). Since the Zagros Mountain Range prevents rainy clouds entering the country from the west, hence a rainy zone and

many farms, orchards and forests have been concentrated there. Crop production is common along with livestock-the summer grazing rangelands are in the high mountainous areas of the Zagros and the lowland rangelands are usually exploited in winter. Overgrazing is more intense on gentle sloping land and in almost dry farming land. Overgrazing has caused considerable emerging unpalatable or spiny species. For instance, Astragalus, Acantholimon, Acanthophyllum are remarkable for their hemispherical or cushion-like thorny aspect (“tragacanth” vegetation), often making up a portion of the vegetation of the high semi-arid mountains (Badripour 2006).

20.3.5 Magnitude of Soil Salinity Water and soil resources salinity is a serious risk in many parts of the country. The average land of Iran, which gets affected by salinity was reported by different researches as presented in Table 20.1. Qureshi et al. (2007) reported that 8.5 and 25.5 million ha of Iran are highly and moderately salt based on the Iranian digital soil map. In addition, soil salinity in the central arid region of Iran is mainly due to some reasons viz. dry climate, salt-rich parent materials, insufficient or lack of drainage and use of saline groundwater for irrigation. The soils with severe to extreme salinity mostly located in the Central Plateau and the Khuzestan Province and southern coastal plains of Iran have soils under sever to extreme salinity.

20.3.6 Magnitude of Forest Fire The frequency of fires affecting both pastures and forests in Iran increased from 15 to 772 during 1982–1995 (Alexandrian and Esnault 1998). In addition, the Bureau of Conservation and Protection Database (FRWO) reported that about 405 forest fires annually affected about 4300 ha/a in average during 2000–2003. More than 99% of coniferous forests are influenced by surface fires. However, fires have increased over the past years, especially due to drought, consequently they can become a serious threat in the future (World Bank 2005).

Table 20.1 Some reports on salt affected soils area in Iran References

Dewan and Famouri (1964)

Soil and Water Research Institute (1987)

Dent et al. (1992)

FAO/UNEP (1994)

Siadat et al. (1997)

FAO (2000)

Sayyari and Mahmoodi (2002)

Estimated salt affected area/%

9.4

10.9

12.8

19.8

9.7–13.9

20.6

15.2

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S. H. Sadeghi and Z. Hazbavi

20.3.7 Magnitude of Flooding

resulting from the loss of around 23,000 ha of wetland reaches some US$350 million, annually (World Bank 2005).

Occurrences of high floods with significant environmental damages have a growing trend in Iran. As shown in Table 20.2, the number of floods recorded in the 1980s and 1990s is more than five times the number recorded in the 1950s and 1960s (DOE 2004). Recently, on April 15, 2017, northwestern Iran influenced by heavy rains resulted in flash flood and caused many serious problems such as ca. 40 people death. The most subjected provinces were East Azerbaijan, West Azerbaijan, Zanjan and Kordestan (www. wikipedia.org). The coastal regions of the Caspian Sea facing ever-increasing river flood incidents. For instance, in Mazandaran Province, 70% of the credit related to damage compensation belongs to floods (Sadeghi-Pouya et al. 2017).

20.3.8 Magnitude of Wetland Loss The importance of wetlands in Iran is universally well documented. Iran possesses over 1000 wetlands of various types, whose significance for global biodiversity is unparalleled in the region (Blake 2016). However, some wetlands are increasingly under pressure because of human activity (World Bank 2005). Wetlands have numerous benefits and services. The value of these benefits and services was estimated by World Bank (2005) at an average of US$960 per hectare per year. The net present value of the damage cost

20.4

Hot Spots of Land Degradation in Iran

In this section, the hotspots of different types of land degradation in Iran as cited and analyzed and have been reported in Tables 20.3, 20.4, 20.5, 20.6, 20.7, 20.8, 20.9, 20.10 and 20.11. This analysis was conducted for nine main geographical division of Iran viz. north, south, east, west, central, northeast, northwest, southeast and southwest of Iran. The spatial patterns of wells, which became out of the work resulting from pollution during the period 2000–2004 are presented has been shown in Table 20.12. Khorasan (northeastern Iran) and Fars Provinces (south and southwestern Iran) have the most polluted wells. The spatial pattern of soil salinity in Iran has also been depicted in Fig. 20.11 (Banie et al. 2001). Major crop production systems in Iran are based on irrigated agriculture, where about 50% of the area falls under different types of salt-affected soils (Cheraghi 2004). Khuzestan and Central provinces have the most saline and sodic affected soils, 17% and 16.5% of total Saline and sodic soils of Iran, respectively (Koocheki and Moghaddam 2004). It is estimated that in areas where salinity is present, average yield losses may be as high as 50% (Siadat et al. 1997; Qureshi et al. 2007). One

Table 20.2 Number of recorded floods in Iran during 1950–1990 decades (DOE 2004)

Decade

1950

1960

1970

1980

1990

Number of flood

192

251

432

1046

1341

Table 20.3 Hotspots of land degradation in northern Iran

No

Hotspot

Land degradation type

References

1

Piedmonts of the Alborz Mountains and Caspian Coastal Plain

Salinity

Moameni et al. (1999)

2

Caspian Sea regions

Flooding

DOE (2004)

3

Northern Coast of Iran

Solid waste leaching, groundwater pollution

World Bank (2005); Pak and Farajzadeh (2007)

4

Guilan Province

Soil erosion and land use change, deforestation

Sadeghi et al. (2008); Bahrami et al. (2010)

5

Alborz Mountains

Land use change, surface erosion and sediment yield

Ahmadi (2011)

6

Korganrud Watershed, Guilan Province

Landscape metrics and land use change

Sheikh Goodarzi et al. (2012)

7

Neka Watershed, Mazandran Province

Land cover and use change

Talebi Amiri et al. (2014)

8

Golestan Province

Desertification

Akbari et al. (2016)

9

Southwestern coasts of Caspian Sea

Oil pollution

Shirneshan et al. 2016

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Land Degradation in Iran

Table 20.4 Hotspots of land degradation in southern Iran

Table 20.5 Hotspots of land degradation in eastern Iran

Table 20.6 Hotspots of land degradation in western Iran

297 No

Hotspot

Land degradation type

References

1

Southern Coastal Plains

Salinity

Moameni et al. (1999)

2

Mangrove forests, southern coast of Iran

Coastal pollution, habitat fragmentation

World Bank (2005)

3

Qareh Aghaj, Fars Province

Water erosion

Masoudi et al. (2006)

4

Zargeh Watershed, sub-basins of Maroon River Watershed

Soil erosion and sedimentation

Safamanesh et al. (2006)

5

Persian Gulf and Oman Sea coastlines

Solid waste leaching, oil and gas pollution

Pak and Farajzadeh (2007)

6

Dasht-e-Jeihoon, Hormozgan Province

Water and wind erosion

Akbarian et al. (2013)

7

Southern coastline of Iran

Sea level rise

Goarnejad et al. (2013)

8

Marmeh Watershed, Fars Province

Soil erosion and sediment yield

Amini et al. (2014)

9

Bakhtegan Lake

Drought and dam construction

Lehane (2014)

10

Bandar Abbas City, Hormozgan Province

Urbanization

Dadras et al. (2015)

No

Hotspot

Land degradation type

References

1

Eastern Iran

Drought

Asadi Zarch et al. (2011)

2

Eastern Iran

Groundwater recharge decreasing

Abbaspour et al. (2009)

3

Sistan Region, Eastern Iran

Wind erosion

Mirmousavi (2016)

4

Mountains of Southern Khorasan Province

Wind erosion

Hamidian Pour et al. (2017)

5

Southern Khorasan Province

Hydrological drought

Shahidi et al. (2017)

No

Hotspot

Land degradation type

References

1

Kordestan

Forest fires

Allard (2001)

2

Chamgardalan Watershed, Ilam Province

Water erosion

Yousefi et al. (2014)

3

Zarivar Lake

Soil erosion, sedimentation, water pollution

Ebrahimi Mohammadi et al. (2014); Sadeghi et al. (2015a, b, 2017)

4

Kashkan-Poldokhtar Watershed

Gully erosion

Rahmati et al. (2017)

of the most serious threats of Iranian territory is wind erosion. General view of spatial patterns of the most dust storm sources in Iran are identified by Mohammadian (2015) and presented in Fig. 20.12.

Finally, spatial patterns of drought in mid-2000 based on the Multivariate Standardized Drought Index (MSDI) are demonstrated in Fig. 20.13. Most of Iran was in an extreme and an exceptional drought. In the Fig. 20.13, D0, D1, D2,

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Table 20.7 Hotspots of land degradation in central Iran No

Hotspot

Land degradation type

References

1

Central Plateau

Salinity

Siadat et al. (1997); Moameni et al. (1999); Qureshi et al. (2007)

2

Central Iran

Drought

Asadi Zarch et al. (2011)

3

Zagros Mountains

Soil erosion, forest conversion to agriculture, overgrazing in forests

Najmoddini (2003)

4

Central Zagros

Overgrazing

Nael et al. (2004)

5

Ghareh Aghach Watershed, Isfahan Province

Erosion, sedimentation

Amiri (2010)

6

Yazd Province

Drought

Dastorani and Afkhami ( 2011)

7

Namak Lake Basin (Maharlu Lake)

Dam construction, drought

Abtahi and Safe (2012); Lehane (2014)

8

Dasht-e Lut

Desert

Yazdi et al. (2014)

9

Kashan ERG

Wind erosion

Rahdari et al. (2014)

10

Chah Jam Erg, Semnan Province

Wind erosion

Yamani and Arabameri (2015)

11

Tehran

Aquifers depletion, land subsidence, urban development, earthquakes

Madanipour (2016)

12

Shazand Watershed, Markazi Province

Rapid industrialization and industrialization, land use change

Davudirad et al. (2016); Hazbavi et al. (2017); Sadeghi and Hazbavi (2017); Hazbavi et al. (2018a, b)

13

Zayandehrood, Isfahan Province

Downstream desertification due to dam construction, rapid urbanization

Jafari and Hasheminasab (2017)

Table 20.8 Hotspots of land degradation in northeastern Iran

Table 20.9 Hotspots of land degradation in northwestern Iran

No

Hotspot

Land degradation type

References

1

Golestan

Forest fire

Allard (2001)

2

Shirindareh river basin, Khorasan Razavi Province

Soil erosion

Behzadfar et al. (2015)

3

Gharesou Watershed

Land use change, soil erosion

Zare Garizi and Talebi (2016)

4

Northeast forests

Forest fire

Abdi et al. (2018)

5

Khorasan Razavi Province

Desertification

Shiravi and Sepehr (2017)

No

Hotspot

Land degradation type

References

1

Anzali Wetland, Guilan Province

Eutrophication

Akbarzadeh et al. (2008)

2

Zanjanrood Basin

Land use change

Ghaffari et al. (2010)

3

Taham-Chai Watershed, Zanjan Province

Sediment yield

Vaezi et al. (2016)

4

Urmia Lake

Anthropogenic interventions in a natural water system, surface water reduction, drought and dam construction, salinity

Lehane (2014), Nazemi (2016)

5

Shar-chi Watershed, West Azarbyjan Province

Transformation of rangelands into rainfed crops in hilly areas with lack of management practices

Hosseini and Ashraf (2015)

20

Land Degradation in Iran

299

Table 20.10 Hotspots of land degradation in southeastern Iran No

Hotspot

Land degradation type

References

1

Hamoon Lake, Sistan and Baluchestan Province

Droughts and water scarcity

Ebrahimzadeh (2009)

2

Jazmourian Wetland

Drought

National Wetland Conservation Strategy and Action Plan (2011)

3

Chahhashm plain, Sistan and Baluchestan Province

Desertification

Aslinezhad et al. (2014)

4

Shahr-e-Babak plain,Kerman Province

Groundwater quality problem

Azareh et al. (2014)

Table 20.11 Hotspots of land degradation in southwestern Iran No

Hotspot

Land degradation type

References

1

Khuzestan

Salinity

Moameni et al. (1999)

2

Khuzestan

Forest fires

Allard (2001)

3

Kakan catchment area, Fars Province

Landslide

Tangestani (2004)

4

Nojian Watershed, Lorestan Province

Water erosion

Haghizadeh et al. (2009)

5

Karkhe River Basin

Land use change, sediment yield

Mahmoudi et al. (2010)

6

Mazayejan plain, Fars Province

Gully erosion

Zakerinejad and Märker (2014)

7

Izeh County, Khuzestan Province

Erodible area, erosion

Haghjou et al. (2014)

8

Karun River Basin

Water pollution

Hosseini-Zare et al. (2014)

9

Ahwaz, Khuzistan Province

Wind erosion

Ashrafi et al. (2014)

10

Parishan Lake

Drought and dam construction

Lehane (2014)

11

Seimare region, Lorestan Province

Gully erosion

Tahmasebipour et al. (2016)

Table 20.12 Spatial pattern of polluted wells in Iran during 2000–2004 (World Bank 2005) No

Province

No. of out of use wells due to pollution

No

Province

No. of out of use wells due to pollution

1

Khorasan

40

8

Kordestan

7

2

Fars

26

9

Qazvin

7

3

East Azerbaijan

17

10

Tehran

7

4

Chaharmahal and Bakhtiari

13

11

Ilam

6

5

Markazi

10

12

West Azerbaijan

6

6

Yazd

10

13

Shiraz

5

7

Khuzestan

9

14

Kordestan

5

15

Ardebil

4

21

Lorestan

3

16

Golestan

4

22

Bushehr

2

17

Qom

4

23

Semnan

2

18

Kerman

4

24

Kohgiluye and Boyerahmad

0

19

Sistan and Baluchestan

4

25

Mazandaran

0

20

Hormozgan

3

—

—

—

300

S. H. Sadeghi and Z. Hazbavi

Fig. 20.11 Spatial pattern of salinity in Iran (Banie et al. 2001)

D3 and D4 indicated the abnormally, moderate, severe, extreme and exceptional droughts as reported by Madani et al. (2016).

20.5

Environmental Impacts of Land Degradation in Iran

The cost of natural resource degradation is predominantly from land and forest degradation. Cropland salinity as well as rangeland, wetland and forest degradation and increased occurrences of floods due to soil erosion all have significant economic impacts.

20.5.1 Environmental Impacts of Erosion and Sediment-Related Issues Soil erosion, as one of the main processes in land degradation, is the single most immediate threat to the world food security (Stocking et al. 1988). Soil erosion in Iran causes irreparable damages to watershed ecosystems and the economy every year. In the past century and especially in recent decades, Iran watersheds have undergone changes in management and coverage. Outcome of destructive forces of past and present problems caused increase of erosion and production sediment of surface watersheds, dramatically.

20

Land Degradation in Iran

301

Fig. 20.12 Dust storm sources in Iran (Mohammadian 2015)

Fig. 20.13 Spatial pattern of drought in Iran (Madani et al. 2016)

In Iran, every year, huge amounts of sediment are carried to the estuaries (Shahzeidi et al. 2012). Soil particle loss from farms and orchards decreases gradually the fertility of soils. Moreover, sedimentation in water channels clogs the water ways; it may also transfer pollutants into farm lands and dams mainly used for irrigation and drinking purposes (Sarmadian et al. 2010; Hosseini and Ashraf 2015). Since soil erosion in Iran is much faster than its formation, considering the present and future potential for soil degradation is very important (Emadodin et al. 2012). Different types of soil erosion affect approximately 1.2 million km2 of the land in Iran. So that water erosion removes some 500 million t soil from about 15 million ha of agricultural land each year (Nazari Samani et al. 2009; Amini et al. 2014). Water erosion also affects agricultural productivity in a number of ways, either directly or indirectly. Overall, the off-site impacts of runoff, sedimentation, loss of reservoir capacity is increasing in the region (Behzadfar et al. 2015). Of course, water and wind are the agents of erosion, but the main causes are improper land use and inappropriate cultural practices. Lack of information for preparing erosion maps for quantitative and qualitative evaluation of sedimentation rates is a major need in the watershed management in Iran (Amiri 2010). The geographical position and agro-ecological conditions of Iran have made it vulnerable to soil erosion and it is one of the Asian countries with a large volume of soil erosion

302

(Mahboubi 2004; Haghjou et al. 2014). Annual erosion rate of some 33 t/ha reveals severity of land degradation and impose huge economic loss to the country (Haghjou et al. 2014). According to the Ministry of Jihad and Agriculture and some statistics, the useful capacity of dams reservoirs annually reduced by one percent (180-236 million m3) due to sedimentation. The damage cost resulting from dam sedimentation was reported in terms of potential loss in irrigated crops by the World Bank (2005). The net present value of this loss in 2002 was assessed to US$370 million. In addition, dam sedimentation also results in the need for dredging activities in irrigation networks. This additional operating cost was estimated at US$1.6 million (World Bank 2005). Furthermore, soil erosion results decrease in crop production and gradual decline in fertility of 10 million ha of rainfed lands of the country (Mahboubi 2004). Lack of soil moisture and vegetation in most areas can facilitate wind erosion directly affect large areas of rich soils (Mirmousavi 2016). The main cause of desertification in Iran are water resource depletion, population pressure, excessive grazing, wrong management practices, and climatic factors (Ghaffari et al. 2010). Dam building is another major human activity, which has accelerated desertification in Iran (Zafarnejad 2009). Although, supply of water for irrigation, domestic needs, power generation, flood control, navigation, and recreational opportunities are the main positive effects of dam building, its environmental and social consequences (Jafari and Hasheminasab 2017) have not been considered yet.

20.5.2 Environmental Impacts of Water Issues Water erosion is more considerable in arid and semi-arid regions such as Iran where there are many restrictions in regard to having sufficient water resources. These regions and their fragile ecosystems are more vulnerable to droughts. Not only water scarcity, but also land degradation in Iran has become a major issue during the past decades, resulted from soil fertility decrease due to land use change, soil degradation and erosion, overgrazing of rangelands, and groundwater exploitation (Ahani et al. 2013). The researchers in Iran have surveyed climatic parameters in different time series especially temperature, precipitation, relative humidity and near surface wind speed (Kousari et al. 2014). Some literature show an increasing trend in average air temperature of Iran especially in central and eastern parts in the same vein with other parts of the world (Raziei et al. 2005; Dastorani and Afkhami 2011). Such climate changes have a major impact on hydrological cycles and consequently on available water resources, flooding, drought frequencies and natural ecosystems. The construction of dams, artificial lakes

S. H. Sadeghi and Z. Hazbavi

and major impounding reservoirs on rivers to supply much of a society water demands is a process, which may cause significant changes to the environment and the ecosystems. Dez, Shahid Abbaspour, Doroodzan, Djiroft, Minab and Pishin are among the main dams of the country affected by problems of sedimentation, water quality, economic, social and cultural issues, operation, salinity, relocation of inhabitants, negative agricultural development and finally improper management (Manouchehri and Mahmoodian 2002).

20.5.3 Environmental Impacts of Land Use Change Human activities induced changes in land cover/ use have extensive impacts on the landscape. In recent years, these changes had an increasingly growth due to irrational use of the natural resources in Iran. Hence, considering the negative effects of the inappropriate use of land and land use change, understanding of the landscape changes over time is necessary for planning and implementation of sustainable management (Sheikh Goodarzi et al. 2012). Regional forest cover in Iran has been declined by the expansion of arable land and population growth, economic development, technological advancement and changes of social and political situation (Emadodin 2008). Although, improvement in the agricultural sector increased productivity greatly during the last 50 years, intensive farming and mismanagement of the deforested areas brought environmental problems and soil impacts such as soil erosion, salinization, acidification, soil compaction and pollution (Bahrami et al. 2008). According to first performed census in Iran in 1956, the number of Iran cities was 201 and the ratio of urban population to whole population was 29%. In 2012 the number of cities became 1331 and the ratio of urban population became 70% of whole population (Dadras et al. 2015). Since 1976, the rural population has only had a 1.33% rate of annual growth, against 4.3% annual growth in the number of urban places (Fanni 2006). Besides that, according to the World Bank report the annual urban population growth in 2014, 2015 and 2016 has been 2%, 1.9% and 1.8%, respectively (databank.worldbank.org). Such unplanned rural to urban migrations led to many socio-economic and environmental changes and faster growth in urban population (United Nations Country Team 2003). The characteristics of the urban system of Iran could be enumerated as high concentration of economic and commercial investment in cities (especially in large cities) and the lack of control over it led to ecological segregation and environmental degradation. This process was intensified because there was no accord on the necessary principles of urban sustainability within development and physical and spatial expansion of large cities and their irregular growth. This was influenced by two

20

Land Degradation in Iran

factors viz. the climatic and natural situation, and the national policy and planning (Fanni 2006). Furthermore, the Iranian revolution of the late 1970s was followed by the Iran–Iraq war (1980–1988), further led to a significant political, economic, cultural, demographic, and social restructuring of the nation (Modarres 2006). Then under the Islamic Republic regime, the development policies were sought to achieve the multiple objectives of modernization, and politically correct Islamic institutional conditions. These objectives were not readily reconciled with each other (Dehesh 1994). On the whole, these urbanization, industrialization and demographic shifts together with economic, social and developmental changes created a situation in which more pressure was being exerted on natural resources (soil, water and vegetation) (Amirarsalan and Dragovich 2011; Davudirad et al. 2016). The analysis of landscape metrics revealed that the extensive replacement of agricultural lands and forests with rangelands increased patch number and decreased mean patch area as two important fragmentation indicators. Therefore, the results necessitated paying attention to the quality of land use and cover for decreasing the natural resources degradation (Talebi Amiri et al. 2014).

20.5.4 Environmental Impacts of Overgrazing Various types of the human-induced soil degradation are visible in many parts of Iran. Evidence shows that long-term human activities and inappropriate exploitation of soil, water and vegetation have had environmental degradation impacts. Overgrazing not only causes soil chemical impoverishment or nutrient mining (Stroosnijder 1996; Engels 2002), but also physical degradation on the majority of the Iranian rangelands. Consequently, their infiltration capacity reduces, causing a larger fraction of annual rainfall to be lost as runoff and this may trigger a dangerous downward spiral, that is under continuing grazing, the situation deteriorates from time to time, leading to complete soil degradation with hardly any primary production (Sadeghi et al. 2008). The ultimate influence of grazing is reducing the vegetative cover, litter availability, infiltration rate and water content and consequently increasing runoff potential and soil loss. It is because of clogging the soil porosities due to excessive trampling, less aeration and water accessibility to microorganism, which ultimately leads to less vegetation cover (Sadeghi et al. 2007).

20.5.5 Environmental Impacts of Soil Salinity Almost 77% of the agricultural land under irrigation in Iran suffers from salinity. The main effect of salinization is the

303

loss of productivity in agricultural lands (Emadodin et al. 2012). Commonly, the worst situations of salinity impacts in Iran occur where the farming communities are relatively poor and face economic difficulties (Khosravi et al. 2013). This situation has forced the local population mainly farmers to migrate to other areas to earn their living. The review of literature demonstrated that salinity problem is also spread over other land uses such as rainfed dryland farming and rangelands areas (Qureshi et al. 2007). In areas with high levels of salinity, plants and living organisms are killed or their productivity severely reduced (World Bank 2005). For Example, the salinity of the Urmia Lake has increased year by year attaining complete saturation, put the life of its fauna and flora at high risk level especially endemic Artemia Salina urmian as a unique species (Agh et al. 2007; Khosravi et al. 2013).

20.5.6 Environmental Impacts of Forest Fire Forest fire phenomenon is of concern in Iran especially in north and southwest parts of Iran, since the likelihood of similar fires in the future is high. For example, in 2010, intermittent forest fires burnt more than 16,000 ha in the northeast areas in just less than one month (Abdi et al. 2012). Air pollution, global warming, devastating loss and irreparable damage to the environment and atmosphere, extinction of rare floral and faunal species, and threaten the lives of people who live near forests are some aspects of environmental forest fire in Iran (Alkhatib 2014; Abdi et al. 2018). Change in the composition and diversity of herbaceous species is considered as another effect of fires (Daryayi et al. 2013).

20.5.7 Environmental Impacts of Flooding The winter and early floods in Iran are the main cause of salinity and water logging in arid and semi- arid regions. Since, in this situation, huge amounts of salts are deposited in the soils as pure water is evaporated during the hot summers (Cheraghi 2004). Flooding in the northern and western Iran is historically a common issue. Torrential rains in August 2001 generated devastating floods that damaged agricultural lands (Thousands ha of farmland) of Khorasan and Golestan Provinces. It also damages the hundreds of lives, and washes away roads and houses, causing millions of dollars in damage. Similar floods were reported again in the western side of the Zagros Mountains during January 2004. A further increase in precipitation could increase the frequency and intensity of floods in the wet regions of the country. The changes in precipitation and blue water resources, as well as the increases in the number of large

304

S. H. Sadeghi and Z. Hazbavi

rainfall events could affect northern and western Iran under larger and more intense flooding events (Abbaspour et al. 2009).

Marshes (Fars); Shadegan Marshes and mudflats of Khor-al Amaya and Khor Musa (Khuzestan) as well as Sheedvar Island (Hormozgan); Shurgol, Yadegarlu and Dorgeh Sangi Lakes (West Azarbayjan).

20.5.8 Environmental Impacts of Wetland Loss

20.6 Iranian wetlands degradation in recent years, has led to degraded biodiversity (e.g., biota, birds, fish, vegetation) and consequently a reduction of ecological functions (National Wetland Conservation Strategy 2011). All wetlands types provide services of water purification and regulation of water flows, fishery, plants, animals and micro-organisms habitats, recreation and tourism. Their intrinsic hydrological processes buffer against extremes as droughts and flooding (Jafari 2009). So, due to wetlands loss, the mentioned important and vital services have been declined as happened for many international wetlands of Iran viz. Alagol, Ulmagol and Ajigol Lakes (Golestan and Mazandaran); Amirkelayeh Lake (Guilan); Anzali Mordab (Talab) Complex (Guilan); Bandar Kiashahr Lagoon and mouth of Sefid Rud (Guilan); Deltas of Rood-e-Gaz and Rood-e-Hara (Hormozgan); Deltas of Rood-e-Shur, Rood-e-Shirin and Rood-e-Minab (Hormozgan); Fereydoon Kenar, Ezbaran and Sorkh Roods Ab-Bandans (Mazandaran); Gavkhouni Lake and marshes of the lower Zaindeh Rood (Isfahan), Gomishan Lagoon (Golestan); Govater Bay and Hur- e-Bahu (Sistan and Baluchestan); Hamun-e-Puzak, (Sistan and Baluchestan); Hamun-e-Saberi and Hamun- e-Helmand (Sistan and Baluchestan); Khuran Straits (Hormozgan); Gori Lake (East Azarbayjan) Kobi Lake (East Azarbayjan); Urmia Lake (West Azarbayjan); Parishan Lake and Dasht-e-Arjan (Fars); Miankaleh Peninsula; Gorgan Bay and Lapoo-Zaghmarz Ab- bandan (Mazandaran); Neiriz Lakes and Kamjan

Conservation Efforts to Control Land Degradation in Iran

During the last two decades, several programs, policies and executive efforts have been taken by the government of Iran with collaboration of many domestic and international bodies at different levels to manage and protect the natural resources against miscellaneous types of land degradation. Accordingly, the Islamic Republic of Iran has had extensive endeavors for sustainable management of natural resources and the environment in consistent with some national laws and a large number of decrees such as the Natural Resources Conservation and Conservation Act, the National Strategic Plan for Environment and Sustainable Development, Combat Desertification and Mitigate the Effects of Drought, and recently, the forestry and rangeland amendments. Iran is also a member of some concerned international conventions and is a member of specialized agencies related to the United Nations viz. Convention on Biological Diversity, Convention on Climate Change, Convention to Combat Desertification, Forum on Forests and Food and Agriculture Organization. To this end, many national and international projects have been launched some of which are still running and some others have been completed as summarized in Table 20.13. The rehabilitation of the desert to stabilize the running sand began in Iran, in 1959. Research on stabilizing running sand methods was initiated in 1969 in Ahvaz City located in

Table 20.13 List of some activities, projects and programs in Iran towards mitigation of land degradation No

Name of project/Program

Place

Collaborator

Financial credit

Duration

Remarks

1

Restoration of forest and demolished lands with special emphasis on lands affected by wind erosion and saline soils

Bam-Kerman and Sarayan-Khorasan South

Global Environment Facility Fund (GEF) and FAO

USD 12.2 million

2011–2015

http://www.rfldl.ir

2

Enhancement and Integration of Organizations for Integrated Resources Management (Minarid)

Yazd, Kermanshah, Sistan and Baluchestan

GEF and United Nations Development Program (UNDP)

USD 20.0 million

2011–2015

http://www.menarid. ir/fa

3

Sustainable management of Hablehrood water and soil resources (Phase 2)

Firoozkooh and Garmsar

UNDP

USD 7.11 million

2011–2015

http://www. hablehroud.ir/fa

4

Carbon sequestration project (Phase II)

South Khorasan

GEF and the United Nations Office of the United Nations

USD 2.1 million

2010–2014

http://www.ircsp.net/ fa (continued)

20

Land Degradation in Iran

305

Table 20.13 (continued) No

Name of project/Program

Place

Collaborator

Financial credit

Duration

Remarks

5

Participatory Forest and Rangeland Management in Chahar Mahal va Bakhtiari Province

Chaharmahal va Bakhtiari

Japan International Cooperation Agency (JICA)

IR 2179 million

2011–2015

https:// openjicareport.jica. go.jp/%20pdf/ 12283545_01.pdf

6

Multicultural management project of Hyrcanian forests (Caspian)

Mazandaran, Golestan and Guilan

GEF and UNDP

USD 7 million

2012–2016

www.chfp.ir

7

Carbon Sequestration in the Desertified Rangelands of Hossein Abad (Phase 1)

South Khorasan

GEF and UNDP

USD 1.7 million

2004–2009

http://www. tehrantimes.com/ news/414,367/IranUNDP-extend-coop-on-CarbonSequestration-Project

8

Flood and debris flow in the Caspian coastal area focusing on the flood-hit region

Golestan Province

JICA

IR 500 million

2005–2006

https:// openjicareport.jica. go.jp/pdf/% 2011839347_01.pdf

9

Ecosystem Conservation of the Anzali Wetland

Guilan-Anzali Wetland

Department of Environment and JICA

IR 500 million

2003–2005

https://en.trend.az/ iran/2221905.html

10

Watershed Management in Karoun Watershed

Khuzestan, Esfahan, Chaharmahal & Bakhtiyari and Kohkilouyeh & Boyerahmad Provinces

JICA

IR 500 million

1999–2000

www.frw.org.ir

11

Sustainable Management of Water and Soil Resources-Sustainable Management of Land &Water Resources (SMLWR) (Hableh Rood- Phase 1)

Firoozkooh and Garmsar

FAO

USD 377,500 + IR 7646.5 million

1997–2000

www.frw.org.ir

12

Caspian Tree Seed Production and Improvement Center

Mahmoodabad, Mazandaran Province

FAO

USD 43,610

1991–1993

www.frw.org.ir

13

Caspian Model Forest Management Plan

Lirehsar, Tonekabon, Mazandaran Province

FAO

USD 1,380,000

1991–1996

www.frw.org.ir

14

Integrated Range Improvement Program

Zarand Saveh, Markazi Province

FAO

USD 510,880

1990–1995

www.frw.org.ir

15

In-service training in watershed management

Tehran and Zanjan Provinces

UNDP

USD 1,450,000 + IR 200 million

1989–1992

www.frw.org.ir

16

South Khorasan Rangeland Rehabilitation and Refugee Income Generating Project

Qaen–South Khorasan Province

International Fund for Agricultural Development (IFAD) and United Nations High Commissioner for Refugee Agency (UNHC)

USD 22,000,000

1989–1996

http://www.fao.org/ 3/a-i3165e.pdf

306

S. H. Sadeghi and Z. Hazbavi

Khuzestan Province, southwestern of Iran (Ahmadi 2008). During the last years, intensive dust storms frequencies Nevertheless, these actions have been required in basic were significantly increased in Iran, while affecting human programming in order to wind erosion control. Over the past health in the southern parts of Iran like the southwestern half century, different approaches have been used to stabilize Khuzestan Province and the northern part of southeastern running sand. One of the ways to expand Nebkazar is in Sistan and Baluchistan Province (Amiraslani and Dragovich prone areas to stabilize the running and stop the spread of 2010). Oil mulching has been used to stabilize sand dunes in desertification (Yamani and Arabameri 2015). Khuzestan Province at least for the past half century because Iran, as a member of United Nations Convention to of the abundance of oil and gas resources in the region Combat Desertification (UNCCD), has executed many pro- (Khalili Moghadam et al. 2015). Over the approximately 30 jects to combat desertification (Amiraslani and Dragovich years from the mid-1960s to mid-1990s, nearly 190,000 ha 2011), it seems these activities in comparison with the rate of of sand dunes were stabilized using oil mulch, and this degradation in the country are not adequate. For example, a measure to combat desertification is continuing as presented study by Jafari and Bakhshandehmehr (2016) in central Iran in Table 20.14. showed that 9.49% (1.01 million ha), 56.4% (6.04 million Windbreaks were also designed and erected at different ha), % (3.4 million ha) and 2.33% (0.25 million ha) of the densities (spacing), heights and lengths based on wind region has been influenced by low, moderate, severe and direction, velocity and intensity. In Iran, various types of very severe desertification, respectively (Jafari and windbreaks are being used but in very limited areas comHasheminasab 2017). pared to oil mulch usage; the most prevalent method is to use Government measures to combat desertification had been dead branches of trees or shrubs and annual grasses. In some initiated in the late 1950s. Indeed, the early cases, rows of trees are planted, mainly around cultivated anti-desertification efforts were administered by the central areas. The native plant species i.e., Haloxylon persicum, office of “Soil and Water Conservation Committee” estab- Calligonum comosum, Smirnovia iranica, Astragalus lished in 1958 at Tehran. Currently, the Bureau of Desert squarrosus and Panicum antidotale are used for controlling Affairs as a part of the Iranian FRWO is in-charge body and soil erosion. The planted vegetation cover has improved concentrates its efforts on 17 provinces (i.e., Bushehr, Fars, infiltration and reduced runoff and erosion, leading to Hormozgan, Ilam, Isfahan, Kerman, South Khorasan, Kho- retention of surface water resources and recharging of rasan Razavi, North Khorasan, Khuzestan, Markazi, Qazvin, groundwater. A list of plants used for biological manageQom, Semnan, Sistan and Baloochestan, Tehran, Yazd) ment of soil and water in different provinces of Iran has been where identified as desertified regions (Amiraslani and summarized in Table 20.15 (Amiraslani and Dragovich Dragovich 2011). As reported by Nateghi (2006), and 2011). Amiraslani and Dragovich (2011), three main groups of Major change in approaches to combating desertification dune stabilization, the legislative framework for managing in Iran took place following the government’s commitment desertification, and desertification research have been doing to the UNCCD. Countries that are party to UNCCD and as anti-desertification interventions in the mentioned pro- affected by desertification agree to prepare a National Action vinces. The dune stabilization measures included runoff Program to Combat Desertification (NAP), which will outcontrol, oil mulch spraying, windbreak establishment, and line future short-, medium-and long-term programs, and the biological measures including planting of seedlings and country’s plans for preventing desertification and mitigating sowing of seeds (Nateghi 2006). the effects of droughts. As an example runoff control efforts, in the 1980s an on-going pilot project was established in sandy plain of Gareh Bygone with mean annual rainfall of 150 mm and 20.14 Sand dune area stabilized by oil mulch in Iran. (Peyke 2000 rural inhabitants (ca. 6000 ha in Fars Province) Table Sabz 2006; Amiraslani and Dragovich 2011 (Kowsar 2007; Pakparvar 1998). By constructing floodYear water spreading systems, aquifers have been recharged (in a Area/ha 67,300 1665–1978 dry year, 27% of the floodwater percolates to the aquifer) 3 92,717 1979–1988 and floodwaters were controlled (on average 10 million m of floodwater is diverted annually); 2-year average pro- 29,672 1989–1993 duction of barley was 700 kg/ha outside the floodwater 3258 1994 spreading system and 2150 kg/ha on terraces within it; 11,365 1995–1999 grazing capacity increased ten-fold; honey production has 19,624 2000–2004 commenced; fresh water supplies were guaranteed; and 2960 2005 local jobs and cooperatives have been created (Pakparvar 4452 2006 1998; Kowsar 2007; Raes et al. 2008).

20

Land Degradation in Iran

307

Table 20.15 Distribution of major plant species used in Iran’s desertified provinces (Haghani and Hojati 2006; Amiraslani and Dragovich 2011) Plant species

1

Atriplex canescens

2

3

4

*

5

6

*

Atriplex lentiformis

9

*

* *

10

*

*

*

*

*

Haloxylon ammodendron

*

*

*

*

*

*

Haloxylon persicum

*

*

*

*

*

*

*

Calotropis procera

*

*

*

8

*

*

Calligonum comosum

*

7

*

11

12

13

14

*

*

*

*

*

15

16

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

Hammada salicornicum *

Panicum antidotale

*

Prosopis juliflor

*

Prosopis spicigera

*

*

*

*

*

*

*

*

*

*

* *

*

*

* *

*

* *

Tamarix stricta

*

*

* *

*

*

Seidlitzia rosmarinus

Ziziphus spina-christi

* *

Nitraria schoberi

Tamarix aphylla

17

*

* *

*

*

*

* * *

*

*

* * *

*

*

1. Bushehr; 2. Fars; 3. Hormozgan; 4. Ilam; 5. Isfahan; 6. Kerman; 7. South Khorasan; 8. Khorasan Razavi; 9. North Khorasan; 10. Khuzestan; 11. Markazi; 12. Qazvin; 13. Qom; 14. Semnan; 15. Sistan and Baloochestan; 16. Tehran; 17. Yazd

According to the report of the FRWO (www.frw.org.ir), Rehabilitation of Forest Landscapes and Degraded Land (RFLDL) project has been started since 1990 in the South Khorasan Province and is now underway in Kerman Province. The fields of projects are in Isfahan, Yazd, Kerman and South Khorasan. RFLDL is a collaborative effort of FRWO, Global Environmental Facility (GEF) and Food and Agriculture Organization of the United Nations (FAO), which supports the efforts of the Government of Islamic Republic of Iran to mainstream environmentally sustainable development approaches through preparation and running community based and integrated land and forest management (SLFM) initiatives. This project, ongoing since mid Aug 2011 in two pilot sites of Rigan and Sarayan, has been designed towards restoration and enhancement of goods and services delivered by the ecosystems as improvement of capacity of degraded lands and forest landscapes in an arid and semi-arid area to be resulted in generation of sustainable livelihoods, further food security and biodiversity as well as desertification control. The unique specification of the project is that it has simultaneously addressed national priorities and local needs. Thus, the project demonstrated a mechanism by which ground realities are reflected in the national policies and the national policies be successfully observed at local level. In other words, local communities get deeply involved in measures and goods and services delivered from the ecosystem are used as a key tool to improve the livelihood of local communities (www.frw.org.ir). Towards introducing applicable and feasible measure and new technologies, many other approaches and techniques for

instance using various soil amendments, conditioners and stabilizers have been innovated or applied most of which have been initially tried at lab experimental scale. Figure 20.14 and respectively show some conducted efforts at laboratorial and field scales for soil erosion control. The results would be up-scaled to be practically applied at field scale. In 1971, the Environmental Protection Organization (EPO) was founded in Iran. According to Blake (2016), the main priorities of EPO for studying the factors of environmental degradation were considered as following: (1) Employment of environmentally-friendly technologies; (2) Establishment of environmentally-sound land use policies; (3) Identification of wildlife habitats of high ecological value; (4) Adaptation of environmental standards for the correct utilization and management of environmental resources; (5) Enhancement of public environmental awareness and; (6) Enforcement of environmental legislation monitoring to prevent further environmental degradation. These priorities are little changed today. Due to ecosystems and climatic variations, the conservation of biological diversity in Iran has become a monumental task (Blake 2016). Additionally, Iran played an important role in the early development of international conservation law. The International Convention on Wetlands of International Importance was concluded at Ramsar located in northern Iran in 1971.

308

S. H. Sadeghi and Z. Hazbavi

Fig. 20.14 Examples of some efforts for soil and water conservation using soil amendments application in plot scale (Akbarzadeh et al. 2009; Gholami et al. 2013; Sadeghi et al. 2015a, b, 2016)

Fig. 20.15 Examples of Anti-desertification activities through the plantation of Haloxylon sp. (Emadodin et al. 2012)

Many watershed and range management projects in Iran have been conducted. However, after more than 40 years, due to increasing amount of the degradation and erosion processes, it looks that these projects could not meet their goals, completely. A lot of these efforts have proven as unsuccessful and unsustainable top down approach (Golrang et al. 2013). In recent years, Iran government developed new strategies to solve these problems. Along this, in 1997, a people centered program for sustainable management of land and water resources, as a joint program of United Nations Development Program (UNDP) and the government of Iran, was initiated. Kushk-Abad Watershed Management Operation was one of these efforts to sustainable management of land and water resources. Kushk-Abad Watershed is located in Khorasan Razavi Province, northeastern Iran and

20

Land Degradation in Iran

characterized by high population density, natural resources degradation and declines in agricultural productivity. Therefore, significant challenges were done to encourage the rural people to participate in maintaining the productivity of land and water resources (Golrang et al. 2013). Recently, because of Iranian wetlands deterioration, the three authorities of Department of the Environment in Iran, UNDP and GEF developed a project with aim to conserve the biodiversity and healthy ecological wetland systems, which are wisely manageable and useable by people (National Wetland Conservation Strategy and Action Plan 2011). Towards this attempt, Conservation of Iranian Wetland Project (CIWP), was initiated in 2005, as a seven-year joint initiative between GEF, UNDP and the Iranian DOE. The systematically remove or substantially mitigate the dangers to sustain Iranian wetland ecosystems was considered as the major objective of CIWP. The CIWP has started the implantation of the activities in three important wetlands of the country viz. The Parishan Lake (Lake Parishan), the Urmia Lake (Lake Urmia) and the Shadegan Wetland as demonstration sites. An overview of the study areas has been shown in Fig. 20.16. This project developed and ratified integrated management plans in the selected study areas to make an effort to disseminate the achieved experiences to the

309

other country wetlands by presenting a managerial system and providing legal tools for implementation of the system (Mohammadian 2015). Another effort was done to conserve and manage one of the most important wetlands in Iran i.e., Anzali Wetland, northern Iran. In this regard, the Japan International Cooperation Agency (JICA) has supported Iran and the project was implemented during 2003–2012. In this project, techniques and information on wetland monitoring and management planning was shared between Iran and Japan. In result of this effort, the Anzali Wetland Management Committee in 2011 was established. Implementation of the second phase of this project to the Memorandum of Understanding (MoU) with Iranian DOE was signed in 2014 with five years of duration. In this pursuit, different organizations including MoU, the Ministry of Jihad-e- Agriculture, Ministry of Energy, Governor of Guilan Province, the Fisheries and Natural Resources section as well as local communities and other stakeholders have participated (Mohammadian 2015). The Middle East and North Africa Regional Program for Integrated Sustainable Development (MENARID) international project, a full size GEF project in Iran, is performed in four type of agro ecosystems viz. rangelands, rainfed

Fig. 20.16 Subjected area to Conservation of Iranian Wetland Project (CIWP) (Mohammadian 2015)

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agriculture, irrigated agriculture and forest or woodlands. It is planned for where cross-sectoral coordination is essential located in five provinces of Sistan and Baluchestan, Kermanshah, Yazd, Semnan and Tehran supposing as pilot sites of the Hablehroud Water and Land Recourses Sustainable Management project. The MENARID project is aligned with GEF policies and priorities in four focal areas of land degradation, international waters, biodiversity conservation and climate change mitigation (Mohammadian 2015). In addition, projects (responsible authorities) of Carbon Sequestration (MoJA, FRWO), Ahwaz and Shiraz Water Supply and Sanitation (DOE), Sustainable Management of Land and Water Resources in Hablehrud Basin (SMLWR)1st Phase (MoJA, FRWO), Conservation of Iranian Wetlands (DOE), Alborz Integrated Land and Water Management (MoJA, Ministry of Energy), Conservation of Biodiversity in the Central Zagros Landscape Conservation Zone (DOE), Northern Cities Water Supply and Sanitation (Provincial government; Water and Sewerage Company (WWC) of Guilan and Mazandaran), Rehabilitation of Forest Landscapes and Degraded Lands with Particular Attention to Saline Soils and Areas Prone to Wind Erosion (MoJA, FRWO) has been progressed in link with MENARID project in Iran. Furthermore, in case of saline water resources management, some large-scale projects have been conducted in Iran. During the last three decades, to ameliorate salt-affected soils and improve their fertility and productivity various following methods have been applied: (1) Removing the excess salts from the root zone; (2) Application of chemical amendments; (3) Mitigating the salinity effects using higher rates of fertilizers; (4) Planting salt-tolerant plant species; (5) Improving the genotypes of commonly grown field crops. Despite all these efforts, mainly due to lack of knowledge of farmers on important aspects of proper management of saline soils and irrigation waters (Qureshi et al. 2007), problems of soil degradation yet keep at irrigated areas. It is seemed that to meet the Iranian population needs, more food and fiber yield is required. This leads to an increase in the use of salt- prone water and land resources for crop production (Qureshi et al. 2007). Since 2012, an IWM National Mega-Project for Iran was also launched. It was approved along with some other very important national-wide projects by the High Council of Sciences, Research, and Technology, Ministry of Education, Research and Technology of Iran in participation with Forest, Rangeland and Watershed Management Organization,

S. H. Sadeghi and Z. Hazbavi

Ministry of Jihad-e-Agriculture, Soil Conservation and Watershed Management Research Institute and some universities of the country. Through a comprehensive research program that integrates multiple disciplines, the national mega project on the integrated watershed management will establish a holistic understanding of Iranian watershed ecosystems and will provide the necessary watershed management models and tools that support evidence-based decision making. The conceptual framework of the project is going to be implemented in several pilot watersheds across the country. Although the process is perceived to be far from straightforward, it is hoped that this integrated participatory watershed management scheme will contribute to a better natural resources management and towards desirable socioeconomic outcomes for the country in line with the sustainable development goals (Sadoddin et al. 2016).

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314 Sadeghi SHR, Ghaderi Vangah B, Safaeeian NA (2007) Comparison between effects of open grazing and manual harvesting of cultivated summer rangelands of northern Iran on infiltration, runoff and sediment yield. Land Degrad Dev 18:608–620 Sadeghi SHR, Azari M, Ghaderi VB (2008) Field evaluation of the hillslope erosion model (HEM) in Iran. Biosys Eng 99:304–311 Sadeghi SHR, Ebrahimi Mohammadi Sh, Chapi K (2015a) Analysis of intra-storm suspended sediment delivery processes from different tributaries to the Lake Zarivar using hysteresis patterns Iranian. J Nat Resour 68(2):323–340 Sadeghi SHR, Gholami L, Sharifi Moghadam E et al (2015b) Scale effect on runoff and soil loss control using rice straw mulch under laboratory conditions. Solid Earth 6:1–8 Sadeghi SHR, Hazbavi Z, Kiani HM (2016) Controlling of runoff and soil loss from small plots treated by vinasse-produced biochar. Sci Total Environ 15:483–490 Sadeghi SHR, Ebrahimi Mohammadi Sh, Singh VP et al (2017) Non-Point source contribution and dynamics of soluble and particulate phosphorus from main tributaries of the Zarivar Lake Watershed Iran. Environ Monitor Assess 189(238):1–13 Sadeghi-Pouya AR, Nouri J, Mansouri N et al (2017) An indexing approach to assess flood vulnerability in the western coastal cities of Mazandaran, Iran. Int J Disaster Risk Reduct 22:304–316 Sadoddin A, Ownegh M, Najafi Nejad A et al (2016) Development of a national mega research project on the integrated watershed management for Iran. Environ Resour Res 4(2):231–238 Safamanesh R, Azmin Sulaiman WN, Ramli MF (2006) Erosion risk assessment using an empirical model of pacific south west inter agency committee method for zargeh watershed Iran. J Spatial Hydrol 6(2):105–120 Sarmadian F, Rahimy P, Keshavarzi A (2010) Modeling of sediment yield and bicarbonate concentration in Kordan Watershed. J Agric Sci Technol 12:121–131 Sayyari MH, Mahmoodi S (2002) An investigation on reason of soil salinity and alkalinity in some part of Khorasan Province (Dizbad-e-Pain Region). In: Paper presented at the 17th World Congress of Soil Science (Symposium No. 33; Paper No. 1981), 14–21 August 2002, Bangkok Shahabfar A, Eitzinger J (2008) Spatial and temporal analysis of drought in Iran by using drought indices. In: European Meteorological Society (EMS), 7th European Conference on Applied Climatology (ECAC) (EMS2008), Amsterdam, The Netherlands, Sep 29th–Oct 3rd 2008 Shahidi A, Khashei A, Nejati M (2017) Assess the impact of climate change on the hydrological drought in Southern Khorasan Province, Iran. In: Proceeding, IEEA ‘17 Proceedings of the 6th International conference on informatics, environment, energy and applications, Jeju, Republic of Korea, March 29–31, pp 38–42 Shahzeidi SS, Entezari MM, Gholami M et al (2012) Assessment rate of soil erosion by GIS (Case study: Varmishgan, Iran). J Basic Appl Sci Res 2(12):13115–13121 Sheikh Goodarzi M, Alizadeh Shabani A, Salman Mahini A, et al. 2012. Landscape ecological metrics-based investigation of land cover/use changes in Korganrud Watershed. J Nat Environ Iran J Nat Resour 64(4):431–441 Shiravi M, Sepehr A (2017) Fuzzy based detection of desertification-prone areas: a case study in Khorasan-Razavi Province. Nat Resour Conserv 5(1):1–12 Shirneshan G, Riyahi Bakhtiari A, Memariani M (2016) Distribution and origins of N-Alkanes, Hopanes, and Steranes in rivers and marine sediments from southwest Caspian Coast, Iran: implications for identifying petroleum hydrocarbon inputs. Environ Sci Pollut Res Int 23(17):17484–17495

S. H. Sadeghi and Z. Hazbavi Siadat H, Bybordi M, Malakouti MJ (1997) Salt-affected soils of Iran: a country report. In: International symposium on sustainable management of salt affected soils in the arid ecosystem. Cairo. Egypt Soil and Water Research Institute (1987) National soil policy and its technical and administrative organization in Iran. Soil and Water Research Institute Publication No. 725, Soil and Water Research Institute, Tehran (In Persian). Solouti S, Babaniavardi M (2011) Desert tour in Lran. Iran Shenasi Publication, Tehran, pp 17–29 Stocking MA, Chakela Q, Elwell HA (1988) An improved method for erosion hazard mapping part I: the technique. Geografiska Annaler 70(A.3):169–180 Stroosnijder L (1996) Modelling the effect of grazing on infiltration, runoff and primary production in the Sahel. Ecol Model 92:79–88 Tahmasebipour N, Rahmati O, Ghorbani NS (2016) Prediction of gully erosion susceptibility Seimare region using certainty factor model and importance analysis of conditioning factors. Iran J Ecohydrol 3 (1):83–93 Talebi Amiri S, Azari Dehkord F, Sadeghi SHR et al (2014) Study on landscape degradation in Neka Watershed using landscape metrics. Environ Sci 6(3):133–144 Tangestani MH (2004) Landslide susceptibility mapping using the fuzzy gamma approach in a GIS, Kakan Catchment area, southwest Iran. Aust J Earth Sci 51:439–450 United Nations Country Team (2003) Common Country Assessment (CCA) for the Islamic Republic of Iran. United Nations, Common Country Assessment, 82 p. http://www.undp.org/content/dam/rbap/ docs/programme-documents/cca/IR-CCA-2003.pdf. Accessed 7 Apr 2020 Vaezi AR, Abbasi M, Bussi G et al (2016) Modeling sediment yield in semi-arid pasture micro-catchments, Northwest Iran. Land Degrad Develop 28(4):1274–1286 World Bank (2005) Iran, Islamic Republic of-Cost assessment of environmental degradation. Was hington, D C: World Bank. http:// documents.worldbank.org/curated/en/401941468284096627/IranIslamic-Republic-of-CostAssessment-of-EnvironmentalDegradation. 90. http:// documents.worldbank.org/curated/en/401 941468284096627/pdf/320430IR.pdf. Accessed 7Apr 2020 WRM, Iran Water Resources Management Company (2015) Statistics on dam projects. http://daminfo.wrm.ir/fa/dam/stats. Accessed 31 May 2015 Yaghoubkhani M (2012) The study of land use changes in the Tehran metropolitan area by using MOLAND model. In: 48th ISOCARP congress, Perm, Russia, 10–13 Sept 2012, 9p Yamani M, Arabameri A (2015) Comparison and evaluation of three methods of multi attribute decision making methods in choosing the best plant species for environmental management (Case study: Chah Jam Erg). Nat Environ Change 1(1):49–62 Yazdi A, Emami M, Shafiee S (2014) Dasht-e Lut in Iran, the most complete collection of beautiful geomorphological phenomena of desert. Open J Geol 4:249–261 Yousefi S, Moradi Kivarz N, Ramezani B et al (2014) An estimation of sediment by using erosion potential method and geographic information systems in Chamgardalan watershed: a case study of Ilam Province Iran. Geodyn Res 2(2):9 Zafarnejad F (2009) The contribution of dams to Iran’s desertification. Int J Environ Stud 66(3):327–341 Zakerinejad R, Märker M (2014) Prediction of gully erosion susceptibilities using detailed terrain analysis and maximum entropy modeling: a case study in the Mazayejan Plain, southwest Iran. Geogr Fis Din Quat 37:67–76 Zare Garizi A, Talebi A (2016) Identification of critical sediment source areas across the Gharesou Watershed, northeastern Iran, using hydrological modeling. Environ Resour Res 4(1):1–25

Part V European Region

Introduction of the First Authors Panos Panagos is Scientific/Research Officer carrying out scientific and research developments related to soil erosion modelling and implementing environmental information systems in the domain of soil protection in the European Commission, Joint Research Centre, Institute for Environment and Sustainability. Email [email protected]. eu. He has made many research achievements such as the Development of the new soil erosion assessment in Europe (2015), Modeller of soil erosion at European scale with a model developed in JRC (RUSLE2015), the domains of soil erosion and soil organic carbon. He is the Project Manager on behalf of JRC in the 7th Framework programme for Research projects and is responsible for the implementation of the Collaboration Agreement No. 31576 between THE EUROPEAN UNION and SWISS FEDERAL COUNCIL. He haspublished more that 70 papers in Peer review journals. Ana Frelih-Larsen, Senior Fellow, Ecologic Institute, Berlin, Germany. Address: Pfalzburger Str. 43 – 44, 10717 Berlin, Germany. Email address: ana.frelih-larsen@ecologic. eu. Telephone number: +49 30 86880 106. Dr. Frelih-Larsen coordinates the Ecologic Institute's activities on agriculture and soil, focusing on the evaluation of EU and national policies for soil and water protection and their role in climate change mitigation and adaptation. She has coordinated consultancy projects for the European Commission and has contributed to various EU research projects in the field of soil protection. Recently, she led a study on the EU-wide inventory of soil protection policies and coordinated an integrated impact assessment of soil protection policies in EU-funded RECARE project. Geographically, she has a strong interest in mountain environments and Central Eastern Europe. A native of Slovenia, she also works in English and German.

Jane Rickson is a professor of Soil Erosion and Conservation in the School of Water, Energy and Environment, Cranfield University, UK. E-mail address: j.rickson@cranfield.ac.uk; +44 1234 750111). Trained as a physical geographer (BSc in Geography, Kings College, University of London), she specialised in land resource management at MSc (Agricultural Engineering) and Ph.D level. She has over 30 years experience of research, consultancy and teaching in soil and water conservation in the UK and overseas. Her focus is on soil degradation processes (with special interest in soil erosion), and their mitigation through sustainable land management practices. She uses multi-disciplinary approaches to integrate the environmental, economic, social, and technological aspects of land resources management in a range of spatial and temporal scales. Her work is directed at UK Research Councils, industry and policy makers at the local, national and international levels. She has published widely in international, peer reviewed journals, conference proceedings, and trade articles. She is a Fellow and President Elect of the Institution of Agricultural Engineers, a Chartered Environmentalist, Fellow of the Higher Education Academy and member of the Institute of Professional Soil Scientists. Katrin Prager, United Kingdom. Senior Lecturer in Geography and Environment at the University of Aberdeen, and Senior Social Researcher in Landscape Governance, The James Hutton Institute. Address: University of Aberdeen, Geography & Environment Department, School of Geosciences, St Mary's, Elphinstone Road, Aberdeen AB24 3UF, Scotland, UK. Telephone number 0044 1224 273795. Email: [email protected]. Katrin Prager has worked at the James Hutton Institute since 2009, following a Ph.D and postdoc work at Humboldt University Berlin, Germany and University of Tasmania, Australia. Recently, she commenced a joint appointment at the University of Aberdeen. She undertakes research relating to the governance and

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management of cultural landscapes, including soil, water, and biodiversity. Her work has changed the way people think about the challenges of coordination of agri-environmental management at local and landscape level, and hasprovided insight to the policy mechanisms by which co-management can be achieved. The concepts and findings are translatable to other European countries and beyond. Linked to this work, she investigates farmer adoption of environmentally friendly farming practices, farm advisory services, citizen science and farmer-led approaches, community empowerment, participatory policy design and policy evaluation. She currently teaches a variety of topics in human geography. Svetla S. Rousseva is a professor working at the Institute of Soil Science, Agrotechnology and Plant Protection “Nikola Poushkarov” in Sofia, Bulgaria. Address: Institute of Soil Science, Agrotechnology and Plant P rotection “Nikola P ous hkarov” 7, ShosseBankya Str., Sofia 1331. Bulgaria. E-mail: [email protected]. She received a MSc in Physics and in Biophysics from the University of Sofia “St. KlimentOhridski” and Ph.D in Soil and Water Conservation from the Institute of Soil Science. Dr. Rousseva is applying this background knowledge to the study of soil and soil degradation threats from the point of view of physics. She believes that soil is a limited non-renewable resource at risk and that soil protection is essential for food security and the sustainable future of mankind. Miodrag Zlatić is a professor at Belgrade University, Faculty of Forestry, in the department of ecological engineering in soil and water resources protection. Dr. Zlatic is the Head of the Erosion and Torrent Control. His professional areas of specialization are sustainable land management (SLM), socio-demographic aspects of land degradation, social, economic and ecological effects of erosion and torrent control, policy of sustainable development of degraded areas, and assessment of risk and uncertainty in SLM. He served as coordinator of several international projects/ programmes in Serbia (WOCAT, Community Based rehabilitation of Degraded Land in Balkans), as well as Editor in Chief of four international monographies and one national monograph. He served as president of the World Association of Soil and Water Conservation from 2005 to 2010, and is presently on the Council of WASWC as immediate past president. Nada Dragović is a professor and is the head of the Department of Ecological Engineering in Soil and Water Resources Protection, University of Belgrade Faculty of Forestry. Address: Kneza Viseslava 1, 11030 Belgrade, Serbia. Email: [email protected]. She was educated at the Faculty of Forestry in the field of erosion and torrent control. Prof. Dragović has published more than 160

Part V: European Region

publications in the following research fields: soil erosion and torrent control, the application of modern planning methods in the organization of works on erosion and torrent control, project management in the field of torrent control, watershed management, research in erosion processes and sediment transport. Ivan Blinkov is a professor in the faculty of forestry at the University of Skopje, Skopje, Republic of Macedonia. Address: ul. “16 Makedonska brigade”, br.1, 1000, Skopje, Republic of Macedonia. Telephone:+389 70 205 782. E-mail: [email protected]. Professor Blinkov received his doctorate from “Ss. Cyril and Methodius” University, Faculty of Forestry, Skopje, Republic of Macedonia. Dr. Blinkov’s areas of research and teaching are focused on erosion and torrent control and watershed management. He haspublished 85 professional papers and has presented professional papers at numerous conferences. He has [published multiple chapters in edited books and has published 4 textbooks. Valentin N. Golosov is a principal research scientist at Lomonosov Moscow State University, Moscow, Russia and Kazan Federal University, Kazan, Tatarstan Republic, Russia. Home address: Odoevskogo st. 3-6-651, Moscow, 117574. Email address: [email protected]. Telephone number: +7-9395044. Dr. Golosov has been a faculty member of the Lomonosov Moscow State University for 36 years. He has published more than 250 articles in domestic and international journals. He has authored and co-authored several books. Dr. Golosov fields of study are quantitative assessment of soil erosion and sediment redistribution rates of agricultural lands, and lateral migration of sediment-associated radionuclides. He is member of Steering Committees of International Sediment Initiative (UNESCO) and WASWAC, former president of the International Commission of Continental Erosion (International Association of Hydrological Sciences), consultant to IAEA on the application of fallout radionuclides for evaluation of sediment redistribution rates. Dr. Golosov has presented papers, consulted with professionals/agencies, and conducted research in over 45 countries. Olga I. Bazhenova is a professor of Geographical Sciences at the Irkutsk State University. She is the lead researcher at the V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk. Home address: 664033, Irkutsk, Lermontov st., 333E-38. E-mail address: [email protected]. Telephone number: +7 395242-64-35. Dr. Bazhenova has been examining soil erosion problems in the south of Siberia for more than 40 years. The primary emphasis of these investigations are process mechanisms, intensity measurement, mapping, and soil conservation practices. She has extensive experience in

Part V:

European Region

long-term field experimental observations of the progress of soil erosion at experimental fields in the semiarid regions of Siberia. She focuses considerable effort on soil degradation in the basin of Lake Baikal, in the agricultural regions of the intermountain depressions of the south of Siberia, IrkutskoCheremkhovskaya and Onon-Toreiskaya plains. She is an author of more than 200 articles on soil erosion issues. Aleksei N. Makhinov is the Director at the Institute of Water and Ecology Problems, Far Eastern Branch of the Russian Academy of Sciences and professor at the Pacific State University. Home address: 56, Dikopoltsev St., Khabarovsk, 680000, Russia. Telephone number: 7 (4212) 32-57-55, E-mail address: [email protected]. Scientific

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interests include physical and evolutionary geography, geomorphology, water resources and erosion-accumulation processes on rivers. He is the head of several international projects on the study of the ecological state of the Amur River; co-leader of the Russian-Chinese-Japanese project on human activities in East-Asia and their impact on bio productivity in the North Pacific. He leads field studies on sustainable water resource development in the northern regions of the Russian Far East and is a member of the professional working group on Russian-Chinese water quality monitoring of transboundary water resources. He is visiting lecturer in East- Kazakhstan Technical University (Kazakhstan) and Tongji University (China). Dr. Makhinov is the author and co-author of 420 scientific publications.

Soil Erosion in Europe: From Policy Developments to Models, Indicators and New Research Challenges

21

Panos Panagos, Emanuele Lugato, Cristiano Ballabio, Irene Biavetti, Luca Montanarella, and Pasquale Borrelli

21.1

Introduction

It takes 100 years to form a single centimeter of new soil under natural temperate grasslands (Alewell et al. 2015). In our days, erosion is known as one of the most critical forms of soil degradation and a major threat to agricultural soil productivity (Montanarella 2015) and thus, in many regions of the world, to societal stability. More than 99% of the world’s food supply comes ultimately from land-based production depending on soils and this should be considered carefully taking into account the population increase to 9 billion given the threat of climate change (Garcia-Ruiz et al. 2017). Intensive farming practices significantly accelerate soil erosion rates (Zhao et al. 2013) up to about two orders of magnitude (Montgomery 2007). The effects of soil erosion can be severe, not only on-site through land degradation and fertility loss but also causing serious off-site damage like siltation of reservoirs, sediment impacts on fisheries, the loss of wildlife habitat and biodiversity, increased risk of flooding, damage of recreational activities, land abandonment or damage to infrastructure (roads, railways and other public assets) (Telles et al. 2013). Soil erosion by water is one of the most widespread forms of soil degradation in the European Union (EU). This was also recognized in the European Union Soil Thematic Strategy (EC 2006) and in the United Nations Convention to Combat Desertification (UNCCD) article 1 (UNCCD 2017). During the period 2013-2017, in the Joint Research Centre (JRC) of the European Commission, the Research group in relation to “Soil Degradation by erosion” has developed a framework for developing models to assess soil erosion by wind (Borrelli et al. 2014, Borrelli et al. 2015; Borrelli et al. 2016a), soil P. Panagos (&)
E. Lugato
C. Ballabio
I. Biavetti
L. Montanarella European Commission, Joint Research Centre, Ispra, Italy e-mail: [email protected] P. Borrelli Kangwon National University, Chuncheon-si, Gangwon-do, Republic of Korea

erosion by water (Panagos et al. 2015a, 2016a) and specific focus on erosion in forestlands (Borrelli et al. 2016b). At the latest stage, this modelling framework was enlarged to include other processes such as soil loss due to harvesting crops (Panagos et al. 2019) and gully erosion (Borrelli et al. 2021). The coupling of soil erosion with soil organic carbon loss was recently developed using the CENTURY process based model to assess the eroded carbon assessment of the European Union (Lugato et al. 2016). Finally, the modelling platform has recently applied at global scale (Borrelli et al. 2017; Panagos et al. 2017b) resulting in the development of Global Soil Erosion Modelling platform (GloSEM). The present article presents the results of soil erosion modelling by water at the European scale, analyses scenarios based on climate change projections, shows the model integration with carbon models and concludes with the main developments at global scale.

21.2

European Policy Context

The current soil erosion modelling framework has as objective to provide results for policy support at European and global scales. The initial drivers of the policy requesting homogeneous and comparable data for soil erosion at European scale is the European Union (EU) Soil Thematic Strategy (EC 2006). In the last decade, the EU defined a set of 45 Environmental, Socio-Economic and Sectoral indicators known as “CAP Context Indicators” in order to monitor, implement and evaluation of the Common Agricultural Policy (CAP) 2014–2020. The indicators monitor the general contextual trends that are likely to have an influence on the implementation, achievements and performance of the CAP 2014–2020 (Fig. 21.1). In collaboration of various European Commission services (DG Agriculture, DG Environment, DG Climate, DG SANTE, DG JRC), the statistical office of the EU (DG ESTAT) has developed agro- environmental indicators to track integration of environmental concerns into the

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_21

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Fig. 21.1 Current policies driving the development of soil erosion indicators in Europe

Common Agricultural Policy (CAP) at EU, national, regional and provincial levels. The agro-environmental indicators track the impact of agriculture on the environment, assess the impact of agricultural and environmental policies on environmental management of farms and provide support agricultural and environmental policy decisions. In a similar context, the EU has set targets for resource efficiency using the Earth’s limited resources in a sustainable manner while minimising impacts on the environment. This policy framework is described in the resource-efficient Europe flagship initiative which is part of the Europe 2020 Strategy. Those 3 main policy developments in the last decade (Soil Thematic Strategy, Common Agricultural Policy and Resource Efficiency-Europe 2020) request homogenous, comparable and updated data and indicators on soil erosion (Panagos and Katsoyiannis 2019). In addition to this, the European Environmental Agency (EEA) updates the status of soil report every 5 years and requests time series of soil erosion data. At global scale, The Sustainable Development Goals (SDG) approved by the United Nations in 2015 include an explicit call towards ending hunger, achieving food security and promoting sustainable agriculture by 2030 (Keestra et al. 2016). The SDG 2 explicitly mentions the relevance of maintaining soil quality for achieving food security while SDG 15 calls for a land degradation neutral world by 2030. Among other soil related global policy initiatives, the Land Degradation Neutrality (LDN), the FAO Voluntary Guidelines for Sustainable Soil Management, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and the United Nations Environment Programme (UNEP) address the need for updated soil erosion assessments (Fig. 21.1). Besides the policy requests, a continental assessment of soil loss may help to: ① quantify the impacts of soil loss at

such a large scale, ② assess the main effects of climate, vegetation and land use changes on soil erosion rates, and ③ prioritise effective remediation programmes.

21.3

Methodology and Model Description

The modelling of soil erosion by water has a long history with first studies published in international journals more than four decades ago (Li 1974). During the last 3 decades an increasing number of erosion models have been developed. In a recent inventory, Karydas et al. (2014) identified 82 water-erosion models classified on different spatial/temporal scales with various levels of complexity. The most commonly used erosion model is the Universal Soil Loss Equation (USLE) (Wischmeier and Smith 1978) and its revised version (RUSLE) (Renard et al. 1997) which estimates long-term average annual soil loss by sheet and rill erosion. USLE has been used throughout the world for a variety of purposes and under many different conditions simply because it seems to meet the need better than any other tool available (Risse et al. 1993). Notwithstanding the USLE empirical origin, in his experimental results Ferro (2010) overcame the limits of the model and he concluded that “USLE is the subsequent logical structure with respect to the variables used to simulate the physical soil erosion process”. The Joint Research Centre (JRC) has responded to the policy requests by developing a high resolution map of soil erosion by water (Panagos and Katsoyianis 2019). Compared to past efforts to develop a similar continental scale map, this new soil erosion assessment aimed to ① use the most updated input layers of precipitation and rainfall intensity, soil, topography, land use and management, ②

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Soil Erosion in Europe: From Policy Developments to Models, Indicators …

predict the effects of land use, climate and policy scenarios, and ③ be replicable, comparable and utilised at a broader scale (other than soil erosion modelling). USLE/RUSLE is a good compromise for wide region application when both a mesh-size comparable with the original developed slope-length scale is applied and information on rainfall, soil and land-use systems is available (Bagarello et al. 2012). RUSLE-type models have demonstrated to be able to reduce a very complex system to a quite simple one for the purposes of erosion prediction (Nearing 2013) while they maintain a thorough representation of the main environmental and anthropogenic factors that influence the process (Renard et al. 1997). The application of the Revised Universal Soil Loss Equation (RUSLE) on European scale has been discussed in the literature and the advantages (Panagos et al. 2015a, 2016a, b, c) of this approach have overcome its limitations (Evans and Boardman 2016; Fiener and Auerswald 2016). Modelling in general and large-scale modelling specifically can not per se aim at an accurate prediction of point measurements, but tests our hypothesis on process understanding, relative spatial and temporal variations, scenario development and controlling factors (Oreskes et al. 1994). As such, our approach can be offered as a helpful tool to policy makers at pan-European scale. We are confident that the simple transparent structure of RUSLE as well as the discussion of the uncertainties of each modelling factor will help to supply objective guidance to policy makers. The main factors affecting the rates of soil erosion by water are precipitation, soil type, topography, land use and land management. As stated above, the most regularly used erosion model is the Universal Soil Loss Equation (USLE) (Wischmeier and Smith 1978) and its revised version (RUSLE) (Renard et al. 1997) which estimates long-term average annual soil loss by sheet and rill erosion. It should be noted that soil loss caused by (ephemeral) gully erosion is not predicted by RUSLE (Poesen et al. 2003). RUSLE is still the most frequently used model at large scales (Renschler and Harbor 2002; Kinnell 2010) as it can process data input for large regions, and provides a basis for carrying out scenario analysis and taking measures against erosion (Lu et al. 2003). In addition, a recent collection of soil loss data in Europe by the European Environmental Information and Observation Network (EIONET) found that all participating countries used USLE/RUSLE (Panagos et al. 2014b) to model soil loss. The revised version of the RUSLE is an empirical model that calculates soil loss due to sheet and rill erosion. The model considers six main factors controlling soil erosion: the erosivity of the eroding agents (water), the erodibility of the

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soil (including stoniness), the slope steepness and the slope length of the land, the land cover and management, and the human practices designed to control erosion. The model estimates erosion by means of an empirical equation: Er ¼ RKLSCP where: Er = (annual) soil loss [t/(ha a)]; R = rainfall erosivity factor [MJ mm/(ha h a)]; K=soil erodibility factor [t ha h/(ha MJ mm)]; L=slope length factor (dimensionless); S=slope factor (dimensionless); C= cover management factor (dimensionless); P = human practices aimed at erosion control (dimensionless). RUSLE2015 improves the quality of estimation by introducing updated (years: 2000, 2010 and 2016), high-resolution (100 m) and peer-reviewed input layers of Rainfall Erosivity, Soil Erodibility, Slope Steepness and Slope Length, Land Cover and Management and the Support Practices applied to control erosion. The RUSLE2015 model (Fig. 21.2) is an hybrid one and introduces important improvements to each of the soil loss factors, adapting them to the latest state-of-the-art data currently available at the European scale. Rainfall Erosivity was calculated from high-resolution temporal rainfall data (at intervals of 5, 10, 15, 30 and 60 min) collected from 1541 well-distributed precipitation stations across Europe (Panagos et al. 2015b). Soil Erodibility is estimated for the 20,000 field sampling points including in the Land Use/Cover Area frame (LUCAS) survey (Panagos et al. 2014a). The Land Cover and management accounts for the influence of land use (mainly vegetation type/cover and crop type) and management practices (mainly in arable lands) with the potential to reduce the rate of soil erosion by water (Panagos et al. 2015c). The Slope Steepness and Slope Length parameters have been calculated using a high resolution Digital Elevation Model (DEM) at 25m (Panagos et al. 2015d). The support practices were estimated for the first time at European level taking into consideration the Good Agricultural and Environmental Conditions (GAEC) and 270,000 earth observations (Panagos et al. 2015e). The model is documented in the European Soil Data Centre (ESDAC), plus in 15 peer reviewed open Access publications. The K-factor is estimated for the 20,000 field sampling points included in the Land Use/Cover Area frame (LUCAS) survey (Orgiazzi et al 2018; Toth et al. 2013) and then interpolated with a Cubist regression model using spatial covariates such as remotely sensed data and terrain features to produce a 500 m resolution K-factor map of Europe (Panagos et al. 2014a). The dataset was verified against 21 regional and national studies from 13 countries. Besides the

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Fig. 21.2 RUSLE2015 model workflow

inclusion of measured texture attributes, the K-factor model included as well the soil structure, permeability, coarse fragments and stone cover. The importance of soil erodibility layer has been recognized with at least 369 citations during the last 7 years (Carvalho-Santos et al. 2016; Virto et al. 2015; Haregeweyn et al. 2017). The R-factor is calculated based on high resolution temporal rainfall data (5, 10, 15, 30, and 60 min) collected from 1 541 well-distributed precipitation stations across Europe (Panagos et al. 2015b). The R-factor model combined the influence of precipitation duration, magnitude and intensity as it was based on high temporal resolution rainfall data covering long periods. The data collection included 29,000 years of high temporal resolution precipitation records and the variability of time series ranged between 7 and 56 years with a Mean of 17.1 years; however, 75% of time series include the period 2000–2010. The data collection was done between March 2013 and June 2014 with very systematic way in participatory approach as almost all Environmental & Meteorological Services from EU Member States contributed to this. For the first time, Rainfall Erosivity Database on the European Scale (REDES) has been compiled and the Erosivity map of Europe is available to the public (Panagos et al. 2015b). According to scholars, the R-factor has been cited 414 times in less than 6 years (among them Bezak et al. 2015; Cervasco et al. 2015; Dominguez et al. 2015). Recently, the monthly and seasonal dataset of erosivity have been developed in the European Soil Data Centre. Spatio-temporal mapping of rainfall erosivity permits to identify the months and the areas with highest risk of soil loss where conservation measures should be applied in different seasons of the year (Ballabio et al. 2017). At European scale, the C-factor was modelled with a newly developed model land use and management

(LANDUM) model. LANDUM distinguishes between non-arable lands where it applies a combination of land-use class and vegetation density while in arable lands C-factor is based on crop composition and land management practices (reduced/ no tillage, cover crops and plant residues) (Panagos et al. 2015c). For all non-arable lands, the C-factor is determined mainly by vegetation. The Non-arable lands cover ca. 75% of the EU. The CORINE Land Cover database (CLC 2012) was used to derive the different land-use classes of non-arable lands in Europe, and to assign a range of C-values for each class. Using biophysical attributes such as vegetation-coverage density (derived from remote-sensing datasets of the Copernicus Programme), a C-value was assigned to each pixel based on the combination of land- use class and vegetation density. For arable lands, the C-factor was estimated using crop statistics from the EU’s Statistical service (Eurostat) and assigning the C-factor values per crop type based on an extensive literature. In addition, the effect of some management practices on soil loss rates was quantified at the European scale for the first time ever. The calculation of the C-factor of arable lands included ① soil-tillage practices, ② cover crops and ③ plant residues. These datasets are available from Eurostat (Eurostat 2014). Land management practices (reduced/no tillage, cover crops and plant residues) decrease the C-factor for Europe by an average of 19.1% in arable lands, with reduced tillage having the largest impact on soil loss rates due to the large areas of application. The successful application of LANDUM model and the C-factor results are also used in relevant studies (Miura et al. 2015; Napoli et al. 2016; Tzilivakis et al. 2016). The P-factor takes into account ① contour farming implemented in EU agro-environmental policies, and the protection against soil loss provided by ② stone walls and ③ grass margins (Panagos et al. 2015e). The P-factor was

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estimated using the latest developments in the EU’s Common Agricultural Policy (CAP) and applying the rules set for contour farming over a certain slope gradient derived from the Good Agricultural Environmental Condition (GAEC) requirements. The 270,000 field observations of the Land use/cover area frame statistical survey (LUCAS 2012) were used to model the presence and density of stone walls and grass margins (van den Zanden et al. 2013). The mean Pvalue for the EU was estimated at 0.97, while in agricultural lands it was estimated at around 0.95. The use of stone walls and the impact of P-factor is much appreciated and used in the literature (Napoli et al. 2016; Agnoletti et al. 2015; Pacheco et al. 2015; Schiefer et al. 2016).

21.4

Results

21.4.1 Spatial and Temporal Analysis of the Soil Erosion 2016 Assessment Soil loss potential is estimated for around 90% of the EU surface (3,912  103 km2 out of a total 4,366  103. The LS-factor is calculated using the recent Digital Elevation Model (DEM) at 25 m and applying the equations proposed by Desmet and Govers (1996). The use of high-resolution (25 m) Digital Elevation Model (DEM) for the whole European Union (Eurostat 2014), resulted in an improved delineation of areas at risk of soil erosion as compared to lower-resolution datasets. The LS-factor data are available for download in two resolutions (25 m, 100 m) from the European Soil Data Centre (ESDAC). The remaining 10% of the surface consists of surfaces that are not prone to soil erosion, such as urban areas, bare rocks, glaciers, wetlands, lakes, rivers, inland waters and marine waters. A map of soil loss in the European Union was produced using RUSLE2015 at 100 m resolution (Fig. 21.3). This resolution depends on the data availability of the input factors. The scale of 100 m pixel size was selected as being the most appropriate because the C-factor layer (at 100 m resolution) can be altered as a result of policy interventions that affect land use at local and regional scale (Karamesouti et al. 2016; Vallebona et al. 2016). The mean annual rate of soil loss due to water erosion for the reference year 2016 is 2.45 t/(ha a)for the potentially erosion-prone land cover in the EU. The total annual soil loss by water erosion in the EU-27 and UK is about 950 million tonnes (Panagos et al. 2020). This would mean a one metre- depth loss of soil from an area corresponding to the size of the city of Berlin, or a one centimetre loss from an area twice the size of Belgium. Soil degradation by water erosion is particularly significant in some countries of southern Europe, namely in Italy [8.6 t/ (ha a)], Greece [4.2 t/(ha a)], Malta [4.5 t/(ha a)] and Spain [3.9 t/(ha a)], but

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also in mountainous countries with high intensity of rain such as Slovenia [7.4 t/(ha a)) and Austria [7.1 t/(ha a)]. Low levels [below 1 t/(ha a)] were registered Denmark, Estonia, Latvia, Lithuania, the Netherlands, Poland, Finland and Sweden. The rates of soil loss by water erosion in Member States level represent national average values and therefore may mask higher erosion rates in many areas even for those countries that have a low mean. The RUSLE2015 has also been run with the CORINE Land Cover 2000 and the baseline scenario where no agricultural management practices are applied. According to the 2000 soil erosion data, the mean soil loss by water erosion was 2.71 t/ (ha a). The application of agricultural management practices (reduced tillage, crop residues, cover crops, grass margins, terraces and contour farming) have contributed to two thirds of this reduction (Panagos et al. 2016a, b, c) while the remaining third is due to land cover change. The increase of forest and artificial surfaces between 2000 and 2016 is considered an important factor for decreasing erosion in the EU (Robinson et al. 2017). Only 0.4% of EU land suffers from extreme erosion [>50 t/(ha a)] and around 4.8% of EU land is subject to severe erosion [10–50 t/(ha a)]. In a statistical analysis, 11.4% of total area subject to moderate/high erosion risk [>5 t /(ha a)] contributes to almost 70% of total soil loss (Panagos et al. 2015f). This estimate is lower compared to the previous estimations that 16% of Europe’s land area is affected by soil erosion (EEA 2003) due to incorporation of CAP measurements and the Soil Thematic Strategy. The average rate of soil loss falls to 2.16 t/(ha a) if the non-erosion-prone areas are included in the statistical analysis. In both cases, the average annual rate of soil loss is significantly higher than the average rate of soil formation in Europe of 1.4 t /(ha a) (Verheijen et al. 2009). Regarding uncertainties, the estimated data on soil erosion are published following a qualitative assessment and compared with EIONET country estimates (Panagos et al. 2014b) showing that the model output matches general erosion patterns across Europe. However, quantitative validation is foreseen to take place against long-term erosion plots. For each input layer, we have performed an uncertainty analysis and relevant maps of standard error have been produced. Moreover, in a sensitivity analysis that we have performed the most sensitive factor is the cover management followed by topographic and climate factors. This implies that the management practices followed by farmers can reduce soil erosion where applied. The major sources of uncertainty are found in some highly erosion-prone CORINE land-cover classes (e.g. sparsely vegetated areas) that demonstrate high variability between Mediterranean regions (badlands) and northern Europe (mixed vegetation with rocks). The use of remote sensing data on vegetation density has proven to be useful for fine-tuning the erosion-factor

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Fig. 21.3 Soil water erosion in t/ (ha a) (cell size: 100 m) in the European Union Non-erosive lands: surfaces that are not prone to soil erosion, such as urban areas, bare rocks, glaciers, wetlands, lakes, rivers, inland waters and marine waters

values. The soil loss predictions in steep and arid areas can be further improved by separating the effects of erodible soil from the effects of rock and gravel surfaces.

21.4.2 Assessment in Agricultural Lands and Soil Erosion Indicator As stated in the policy development section above (Fig. 21.1), soil erosion by water is among the agro- environmental indicators developed by the European Commission services for monitoring agricultural and environmental

policies. The map of soil loss in the EU (Fig. 21.3) supports the statistical service Eurostat with aggregated data at various geographic levels (national, regional, provincial). Moreover, for the implementation of Common Agricultural Policy (CAP) in the EU, an indicator of the severe erosion has to be provided. As such the CAP focuses on soil erosion in agricultural lands and requests indicators of soil erosion in agricultural lands. According to the definition of the indicator, JRC aggregates the data of high resolution maps in order to provide both mean soil erosion rates and the estimated agricultural area affected by moderate to severe water erosion [>11 t/(ha a)]. An example of the data provided for

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Fig. 21.4 The percentage of agricultural land under severe erosion [>11 t/(ha a)] at province level

the CAP context indicator is presented in Fig. 21.4. The map shows the percentage of agricultural land which is threatened under severe erosion [>11 t/(ha a)] at the province level. In line with this indicator, 6.6% of the EU-27 and UK total agricultural area was estimated to suffer from moderate to severe erosion in 2016. This share was higher in the old EU Member States, known as the EU-15 (7.7%), than in the new EU Member States (joined after 2004), known as the EU-13 (4.3%). Cultivated land (arable and permanent cropland) was estimated to be more affected (7.2%) than permanent grasslands and pasture (4.4%). The share of agricultural land estimated to suffer from moderate to severe erosion was highest in Slovenia (42.4%), Italy (32.8%) and Austria (19.9%), followed by Greece (10.2%), Romania (9.1%), Spain (9.8%) and Croatia (6.4%). In contrast, the lowest share of estimated agricultural area affected by moderate to severe water erosion (11 t/ (ha a)]. Reducing soil erosion by 2030 requires stringent soil protection policies and efficient monitoring systems for detecting changes in soil condition and properties. Unfortunately, the withdrawal of the proposed EU Soil Framework Directive by the European Commission in 2014 leaves the EU without a legal basis for implementing effective soil protection strategies. Focusing on agricultural lands, the application of the Common Agricultural Policy (CAP) and the introduction of management practices such as reduced tillage, crop residues, cover crops, grass margins, terraces and contour farming,

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has reduced soil erosion by 19% in EU-27 and UK during the period 2000–2016. The current setting of RUSLE2015 model permits to run scenario analyses based on climate change, land use change and policy interventions. According to current climate change projections and the research done on future rainfall erosivity, it is expected to have an increase in extreme rainfall events in the long future (2050–2070). This will trigger higher erosion and reduce agricultural productivity. The current land use projections estimate a slight increase of forests and urban lands at the expense of semi-natural or arable lands. However, this cannot compensate for the increase of soil erosion due to climate change. The proposed modelling platform allows to estimate the impact of anti-erosion measures and environmental-friendly management practices in receding the soil erosion. An important development is the integration of soil erosion model with the soil carbon one. High uncertainty still exists on terrestrial carbon balance components in the role of erosion on the global carbon cycle. Although the agricultural soils may act as a source or sink of CO2 depending on the assumptions, erosion seems to induce net carbon fluxes in the same order of current carbon gains from improved management (Borrelli et al. 2016c). Ultimately, we strongly support the idea that erosion should be prevented or reduced by agricultural and environmental policies plus sustainable management practices, in order to maintain the soils in stable and good conditions (Montanarella 2015) and increase their resilience to human and natural perturbations. Another important aspect is the potential spatial displacement and transport of soil sediments due to water erosion at European scale. It is important to estimate the soil loss and deposition rates by estimating sediment transfer and fluxes. So, the sediment delivery models (WaTEM/SEDEM) are coupled with the current estimates of soil erosion estimates. In addition, EUSEMP integrates the sediments trasfer datasets with the pan-European soil contamination data to estimate fluxes of heavy metals (e.g. mercury) and other contaminants to the river basins (Panagos et al. 2021b). Water erosion is a more significant threat compared to wind erosion. Wind erosion is estimated to be considerably less than water erosion as the mean rate of soil loss by wind in the EU amounted to 0.53 tonnes per hectare per year only in arable lands. The total annual soil loss by wind is estimated to 53 million tonnes (Borrelli et al. 2017b). The soil loss by crop harvesting is estimated to about 14.7 million tonnes in EU arable lands representing just 1.5% of the water erosion (Panagos et al. 2019a). The current assessments of soil erosion in EU includes soil loss by water erosion, wind and harvesting crops but still does not consider gully erosion nor erosion due to tillage, which can be locally significant in their own right.

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Panagos P, Ballabio C, Meusburger K et al (2017a) Towards estimates of future rainfall erosivity in Europe based on REDES and WorldClim datasets. J Hydrol 548:251–262 Panagos P, Borrelli P, Meusburger K et al (2017b) Global rainfall erosivity assessment based on high-temporal resolution rainfall records. Sci Rep 7:4175 Panagos P, Borrelli P, Lugato E et al (2018) Cost of agricultural productivity loss due to soil erosion in the European Union: From direct cost evaluation approaches to the use of macro- economic models. Land Degrad Dev 29(3):471–484 Panagos P, Borrelli P, Poesen J (2019) Soil loss due to crop harvesting in the European Union: A first estimation of an underrated geomorphic process. Sci Total Environ 664:487–498 Panagos P, Katsoyiannis A (2019) Soil erosion modelling: The new challenges as the result of policy developments in Europe. Environ Res 172:470–474 Poesen J, Nachtergaele J, Verstraeten G et al (2003) Gully erosion and environmental change: Importance and research needs. CATENA 50(2–4):91–133 Panagos P, Ballabio C, Poesen J et al (2020) A soil erosion indicator for supporting agricultural, environmental and climate policies in the European Union. Remote Sens 12(9):1365 Panagos P, Ballabio C, Himics, M (2021a). Projections of soil loss by water erosion in Europe by 2050. Environ Sci Policy 124:380–392. https://doi.org/10.1016/j.envsci.2021.07.012 Panagos P, Jiskra M, Borrelli P, et al. (2021b) Mercury in European topsoils: Anthropogenic sources, stocks and fluxes. Environ Res 201:111556. https://doi.org/10.1016/j.envres.2021.111556 Renard KG, Foster GR, Weesies GA et al (1997) Predicting Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE) (Agricultural Handbook 703). US Department of Agriculture, Washington DC, p 404 Renschler CS, Harbor J (2002) Soil erosion assessment tools from point to regional scales—the role of geomorphologists in land management research and implementation. Geomorphology 47(2–4):189– 209 Risse LM, Nearing MA, Laflen JM et al (1993) Error assessment in the universal soil loss equation. Soil Sci Soc Am J 57:825 Robinson DA, Panagos P, Borrelli B et al (2017) Soil natural capital in Europe: A framework for state and change assessment. Sci Rep 7:6706

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Schiefer J, Lair GJ, Blum WEH (2016) Potential and limits of land and soil for sustainable intensification of European agriculture. Agr Ecosyst Environ 230:283–293 Telles TS, Dechen SCF, de Souza LGA et al (2013) Valuation and assessment of soil erosion costs. Scientia Agricola 70(3):209–216 Toth G, Jones A, Montanarella L (2013) The LUCAS topsoil database and derived information on the regional variability of cropland topsoil properties in the European Union. Environ Monit Assess 185(9):7409–7425 Tzilivakis J, Warner DJ, Green A et al (2016) An indicator framework to help maximise potential benefits for ecosystem services and biodiversity from ecological focus areas. Ecol Ind 69:859–872 UNCCD (2017) United Nations to Combat Desertification. http://www. unccd.int/en/about-the-convention/Pages/Text-Part-I.aspx 2017–11. Vallebona C, Mantino A, Bonari E (2016) Exploring the potential of perennial crops in reducing soil erosion: A GIS-based scenario analysis in southern Tuscany, Italy. Appl Geogr 66:119–131 Van Der Zanden EH, Verburg PH, Mucher CA (2013) Modelling the spatial distribution of linear landscape elements in Europe. Ecol Indic 27:125–136 Van Oost K, Govers G, Desmet P (2000) Evaluating the effects of changes in landscape structure on soil erosion by water and tillage. Landsc Ecol 15(6):577–589 Van Oost K, Govers G, Cerdan O et al (2005) Spatially distributed data for erosion model calibration and validation: the Ganspoel and Kinderveld datasets. Catena 61:105–121 Van Oost K, Quine TA, Govers G et al (2007) The impact of agricultural soil erosion on the global carbon cycle. Science 318 (5850):626–629 Verheijen FG, Jones RJ, Rickson RJ et al (2009) Tolerable versus actual soil erosion rates in Europe. Earth Sci Rev 94(1–4):23–38 Virto I, Imaz MJ, Fernández-Ugalde O et al (2015) Soil degradation and soil quality in Western Europe: current situation and future perspectives. Sustainability (Switzerland) 7(1):313–365 Wischmeier W, Smith D (1978) Predicting Rainfall Erosion Losses: a guide to conservation planning. Agricultural Handbook No. 537 U. S. Department of Agriculture, Washington DC, USA Zhao G, Mu X, Wen Z et al (2013) Soil erosion, conservation, and eco-environment changes in the loess plateau of China. Land Degrad Dev 24(5):499–510

Soil Protection Policies in the European Union

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Ana Frelih-Larsen and Catherine Bowyer

22.1

Introduction

Soil degradation in the European Union remains a serious ongoing challenge for environmental policy making, sustainable resource management and sustainable development more broadly. Various socio-economic and natural drivers put pressure on soils, ranging from inappropriate farming or forestry practices, expansion in road building and urbanization, habitat loss and degradation and contamination due to industrial activities and waste management. The resulting soil threats, including soil erosion, soil sealing, contamination, loss of soil organic matter, floods and landslides, and compaction, limit the ability of soils to perform soil functions and deliver valuable ecosystem services. These deteriorating trends are expected to continue in the future as shown, for example, by the 2015 State of the European Environment Report (EEA 2015). Soil management and soil policy action in the EU has increasingly been linked to discussions on delivery of ecosystem services and more broadly recognized for their role in addressing multiple complex environmental problems, including water protection, biodiversity conservation and climate change. Not just the state of soils is recognized, but increasingly their role in delivering public goods to the

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement n°603,498 (RECARE project) and from the Horizon 2020 Research Programme under the grant agreement n°635,750 (ISQAPER project). The work presented here builds also on the project Updated Inventory and Assessment of Soil Protection Policies in EU Member States, funded by the European Commission, DG Environment.

A. Frelih-Larsen (&) Ecologic Institute, Berlin, Germany e-mail: [email protected] C. Bowyer Institute for European Environment Policy, London, UK

society and supporting the achievement of the internationally agreed Sustainable Development Goals (SDGs) and goals for climate mitigation. Despite the growing awareness of the importance of soils and efforts to develop a coherent protection framework for soils, soils are the only resource in Europe which does not have a binding legislation (i.e., a Directive or Regulation) at the EU level. Instead, soil protection is directly and indirectly addressed across a wide range of EU policy domains, including those focused on water, biodiversity, air, waste, and climate change. To add to the complexity, the EU policy requirements are implemented in Member States with varying degrees of flexibility. Many Member States have also put in place national initiatives which go beyond legal or policy requirements at the EU level, such as soil protection laws or legislation protecting agricultural soils from being built upon. In a recent study for the European Commission, we identified 35 EU level policies and 671 instruments across the 28 EU Member States which have either explicit reference to soil threats or soil functions, or implicitly offer some form of protection for soils (Frelih-Larsen et al. 2016). This scattered nature of soil relevant provisions along with the multi-level governance of the EU results in a complex policy landscape for soil protection. Careful framing and focus is, therefore, needed to identify the most important instruments with relevance and potential for soil protection. In this chapter, we aim to give an overview of the most relevant EU level policy instruments and requirements for soil protection across key thematic areas or policy clusters, illustrating the strengths of the EU provisions and pointing to the most important successful policy initiatives. Moreover, we tease out the key opportunities and threats for the future of soil protection in the EU. The chapter begins with a brief background section where we ① examine the competence and role of the European

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_22

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Union in relation to environmental policy, which sets the overall context for soil protection; ② outline the policy context and history of soil protection efforts and initiatives at the EU level. We then review the most relevant EU policy instruments for soil protection showing their key strengths and gaps, reviewing this at an individual policy level but also based on “policy clusters” to enable commonalities and gaps to be better understood. Finally, we conclude with reflections on what implications the current policy setup and outlook has for Europe as a region to meet its environmental goals and its global commitments.

the wider community interest” (then Article 235 now Article 352 TFEU). The lack of a clear basis and justification for environmental law making was criticized by a number of Member States (including Germany and UK), not least as it potentially limited the scope of environmental action. This was remedied in 1987 when a new “Environmental Title” (Articles 130r–t) was introduced by the 1987 Single European Act. For the first time this provided an explicit legal underpinning to the Community’s environment policy. The objectives of the Environment Title set out in the Single European Act were broad:

22.2

(1) To preserve, protect and improve the quality of the environment; (2) Contribute towards protecting human health; (3) Ensure a prudent and rational utilization of natural resources. Action relating to the environment was to be based on the principles that: (4) Preventive action is to be taken; (5) That environmental damage should be rectified at source; (6) That the polluter should pay; (7) Environmental protection requirements shall be a component of the Community’s other policies.

Background

22.2.1 Environmental Policy Making in Europe The year 1972 marked the birth of environmental policy at EU level, as well as in the international arena. In this year the European Heads of State and of Government adopted a declaration at the October Council Meeting in Paris which emphasized the importance of a Community Environmental Policy and to this end invited the Community Institutions to establish a program of action accompanied by a timetable (European Community 1973). Earlier in 1972 (5 th of June), the United Nations Conference on the Human Environment was held in Stockholm, an event that inspired action in Europe and led to the creation of government environment agencies and the UN Environment Program (Grieger 2012). In November 1973, the EU Council adopted a “Programme of Action of the European Communities on the Environment”. This program set out actions to be taken forward by the Commission to reduce pollution and nuisances; improve the natural and urban environments; deal with environmental problems caused by the depletion of certain natural resources; and promote awareness of environmental problems and education (Farmer 2012). This prompted the adoption of some of the first pieces of “environmental” legislation, including the Waste Framework Directive (1975) and the Birds Directive (1979). In 1981, the European Commission created its Directorate-General dedicated to Environment (EEA 2007). The European Union is based on the rule of law. This means that every action taken by the EU is founded on treaties that have been approved voluntarily and democratically by all the EU Member States (European Commission 2017). Building on the 1973 Programme of Action, some 200 items of environmental legislation were agreed by 1987. These were justified legally either by the need to ensure a consistent legal base so as not to inhibit the functioning of the Common Market [under Article 100 of the then Treaty, now Article 115 Treaty on the Functioning of the EU (TFEU)]; or under the “catch-all” clause that action was “in

Subsequent Treaty changes from Maastricht in 1992 to Lisbon in 2009 have continued to strengthen, amend and nuance the basis for environmental policy making in Europe. These evolutions are set out in the Table 22.1.

22.2.2 Legislating on Soil Protection in Europe When considering legislating to protect soils in Europe there are some challenges that can be considered specific to the nature of EU environmental law making and its historical evolution. There are other elements that reflect more the inherent nature of what soils are and the challenges and opportunities faced when regulating soil management. The following sections examine the challenges inherent in regulating soil health and the history of soil protection within EU law. 1. Regulating soil health—the inherent challenges and opportunities Soil is a challenging resource to regulate, assess and monitor. Soils across the European Union are extremely diverse, the European Environment Agency has identified over 20 major soil types across 4 climatic zones (EEA 2010). The extent and the type of degradation problem depends upon the scale and nature of external pressures combined with the

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Table 22.1 The shifting context for law making on the environment

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Treaty, Date

Key changes in content on the environment

Treaty of Rome, 1958

Establishes the European Economic Community but contains no mention of environment or protecting elements of the environment

Single European Act, 1987

Environmental title added to the Treaty, plus requirements on integration of environment into other areas of law making

Maastricht Treaty, 1993

Sustainable growth respecting the Environment becomes a task of the Community (Article 2), the requirement to abide by the precautionary principle is added to the existing environmental provisions and the requirements on environmental integration are reinforced

Amsterdam Treaty, 1999

Article 2 requirements are strengthened so that “sustainable development of economic activities” is made an explicit objective of the EU. The prominence of requirements on environmental integration are increased

Lisbon Treaty, 2009

Article 2 is again strengthened to state that the EU shall work for the “sustainable development of Europe” and the “sustainable development of the Earth”

sensitivity and resilience of the land itself; the latter is in turn determined by a soil’s character and the management practices applied. The impacts of degradation processes will depend upon how the land interacts with the surrounding air and water resources, as well as human settlement and land-use needs. Soil degradation is part of a continuum, the different soil- degradation processes are not distinct from one another and nor is the quality of a soil distinct from the broader protection of the environment (Bowyer et al. 2008). Public interest in soil protection can be difficult to garner. Industrial and point source soil contamination, such as mining or other industrial pollution events, have a more direct and visible link to human health impacts thus the potential to act as an overt driver for political action. Slow and diffuse degradation of soils are often not visible, with the impacts of this degradation often seen once a certain tipping point is reached, i.e. when the damage has been done. In addition, impacts can often be distant or tangential to the actions and pressures that are the source of the soil degradation (e.g. in the loss of water quality, release of methane or nitrous oxide emissions in air, sedimentation downstream and changes in flood risk, or loss of above ground biodiversity). The lag between investment in soil protection and the benefits being experienced by landowners or land managers (i.e. people often talk about investment in soil protection in the context of preserving resources for future generations or the need to preserve ecosystem services for the benefit of wider society), also means that the economic interest and benefits of soil protection are not seen immediately or by those most directly involved in their delivery. Pressure on land use and soils is anticipated to increase into the future. This is a consequence of expanding populations, expanding numbers of households, changing patterns of demand including for land intensive commodities such as meat and the increased pressure to meet our energy demand through use of biomass. Climate change and our

need to adapt are also anticipated to change the land resource available and the uses to which it can be put. This represents an opportunity as well as a risk in that, in Europe at least, soil management as a route to wider environmental protection is rising higher in the political agenda. One of the key challenges and opportunities for policy makers is that the possible solutions for addressing soil degradation are as diverse and varied as the situations and circumstances under which they might be applied. The range of socio-economic activities and sectors that affect soils mean that soil protection is very much a cross-cutting policy issue, dealing with a complexity of drivers and pressures; this all adds to the difficulty of regulating the resource. Conversely, however, to achieve soil health (i.e. limiting future degradation, improving already degraded soils and promoting the ecosystem services that soils can deliver) there are an array of different potential intervention points and numerous different political and social drivers. The multiplicity of end points, goals and mechanisms for achievement based on a given intervention mean that there are potentially significant opportunities and motivators to deliver soil protection. Moreover, there is added value across numerous policy spheres and environmental objectives associated with particular interventions. The challenge for delivering soil protection is connecting these elements, the actors, the stakeholders and the value associated with intervention. 2. A history of soil protection policy in Europe There is currently no EU law dedicated specifically and exclusively to the protection and preservation of soils across the Member States. This is not a consequence of the lack of appreciation of the important roles soils play in delivering benefits to society and supporting wider environmental goals. Rather it is a story of missed opportunities and the

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difficulty in balancing the protection of soil, land rights and land values and the associated political sensitivities of Member States. The EU’s first Programme for Action on the Environment adopted in 1973 acknowledged and made clear reference to the need to protect Europe’s soils (citing soil protection issues seven times in the text). This was set out in terms of: the valuable role farmers play in tending the soil and the land and that it is in the interest of the general public to encourage this role; the need to protect soil from erosion and the use of afforestation as a tool to do so; the need for research into single-crop systems and other practices connected with arable farming that might impoverish the soil or change its properties; and the need to monitor the acidification of soils linked to sulfur dioxide emissions. At a strategic level soil protection remains relevant and acknowledged. For example, Paleari (2017) identified eight strategic EU objectives considered to address soil protection and its ecosystem services. These include goals for resource efficiency (2050 EU economy grows in a way that respects resource constraints), no net land take (2050), species and habitat conservation (2020 halting biodiversity loss), accounting for natural capital and ecosystem services (2020), that impacts of drought and floods are minimized through increased water retention in soils (2020). The desire to develop a coordinated policy for Europe’s soils was first set out in commitments made within the Sixth Environmental Action Plan (6EAP). The 6EAP highlighted that “soil is a finite resource that is under environmental pressure”. It stated that one of its objectives is the “promotion of a sustainable use of the soil, with particular attention to preventing erosion, deterioration, contamination and desertification”. It also required “a thematic strategy on soil protection (to be developed), addressing the prevention of, inter alia, pollution, erosion, desertification, land degradation, land-take and hydrogeological risks taking into account regional diversity, including specificities of mountain and arid areas”. A Thematic Strategy for Soil Protection setting out policy action needed was adopted in 2006. This highlighted the extent of soil degradation in the EU Member States and proposed a way forward based around four pillars: (1) Framework legislation with protection and sustainable use of soil as its principal aim; (2) Integration of soil protection in the formulation and implementation of national and Community policies; (3) Closing the current recognized knowledge gap in certain areas of soil protection through research supported by Community and national research programs; (4) Increasing public awareness of the need to protect soil.

A. Frelih-Larsen and C. Bowyer

Alongside the Thematic Strategy a proposal for a dedicated Framework Directive for the protection of soil was published by the European Commission. This was intended to set out a dedicated legal basis for actions to protect soil in the EU including defining key threats and functions of soils, setting out approaches to soil remediation and monitoring of soils condition, and providing a basis for integration of soil protection goals into other policies. For a proposed item of environmental legislation to become a binding EU law the text proposed by the European Commission must be approved by what is known as the co-decision procedure (i.e., it must be approved by the European Parliament and the European Council). The European Parliament adopted its first reading on the proposal in November 2007. At the March 2010 Environment Council, a minority of Member States blocked further progress of the proposed Directive on the grounds of subsidiarity, excessive cost and administrative burden (European Commission 2012). The proposed Directive for Soil Protection was eventually withdrawn in 2014 following Member States failure to reach an agreement on the text (European Commission 2014). Following the withdrawal of the proposed Directive on Soil Protection the European Commission has restated its commitment to the protection of Europe’s soils and the need for sustainable soil management was reiterated in the Seventh (and most recent) Environment Action Programme. This strategic document is non-binding but states the goal that by 2020 “land is managed sustainably in the Union, soil is adequately protected and the remediation of contaminated sites is well underway” and commits the EU and its Member States to “increasing efforts to reduce soil erosion and increase organic matter, to remediate contaminated sites and to enhance the integration of land use aspects into coordinated decision-making involving all relevant levels of government, supported by the adoption of targets on soil and on land as a resource, and land planning objectives”. It also states that “The Union and its Member States should also reflect as soon as possible on how soil quality issues could be addressed using a targeted and proportionate risk-based approach within a binding legal framework”. It should also be noted that the EU institutions are clearly not the only law makers active or relevant to the delivery of soil protection policies in Europe. National and regional legislators exist across all Member States. Some EU countries already having well advanced and coherent soil legislation in place, others have no or very limited soil-focused policies (Frelih-Larsen et al. 2016). There is therefore, a huge array of policies with the potential to impact on soil quality and protection across the European Union, the

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challenge is unraveling what these actually mean, their relevance and the opportunities they can deliver for improved soil management into the future.

Box 22.1. Content of the proposed, then repealed, Soil Framework Directive If the Soil Framework Directive proposal that accompanied the Soil Thematic Strategy had been adopted, it would have set out a framework for the protection of soil and the preservation of the capacity of soil to perform soil functions (COM 232/2006). The proposed Directive contained key requirements around the framing of soil with EU law and the integration of soil issues into the wider environmental acquis and beyond, e.g. within requirements set out in cross compliance under the CAP. The Proposal also put forward the concept of soil functions in EU law. It proposed the harmonization of key definitions and monitoring practices and required the integration of soil issues in other EU and national legislation. The main requirements that were laid out by the Proposal included: Identification of “risk areas”: (1) Member States would have had to identify the areas (“risk areas”) in their national territory where there was evidence or grounds of suspicion that one or more soil degradation processes occurred or are likely to do so in the near future (2) For each risk area, Member States would have had to draw up a program of measures including at least risk reduction targets, the appropriate measures for reaching those targets, a timetable for implementation and an estimate of the funding allocation. The programs would have had to be in place at the latest eight years after transposition date and reviewed every ten years Contaminated sites: (1) Member States would have had to take appropriate measures to limit the intentional or unintentional introduction of dangerous substances in the soil (Article 9) (2) Member States would have had to also identify the sites in their national territory where there was a confirmed presence of dangerous substances (“contaminated sites”) at a level to pose a significant risk to human health and the environment

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and establish an inventory of contaminated sites, to be reviewed every five years (3) Where a contaminated site was to be sold, the owner of the site would have to produce a soil status report (4) Member States would have had to ensure that contaminated sites were remediated and would have had to prepare a National Remediation Strategy USealing: Member States would have had to take appropriate measures to limit sealing or to mitigate its effects, where it was carried out

22.3

EU Policies for Soil Protection

The wide range of EU policies which impact on or interact with soil protection can be broadly grouped in six priority policy clusters or thematic areas. These clusters are considered as key topics for soil protection in Europe and allow the exploration of issues around relatively distinct policy areas. Each policy instrument is allocated to one primary topic although some policies cover more than one policy cluster. The aim is to enable the multiple different polices not only to be analyzed for their own coverage but to gain understanding as to how they interact and deliver protection collectively-which is more akin to how policy making is developed. The clusters identified for analysis are: (1) Overarching instruments (including strategies and funds); (2) Industrial (point source) contamination of land; (3) Agriculture and forestry; (4) Diffuse pollution and water management; (5) Nature, land use planning and soil sealing; (6) Climate change and energy. Table 22.2 gives an overview of these policy instruments and the relevance of the legislation to different policy areas and soil threats, as well as their potential impact for soil protection. The actual impact of policies or their effectiveness in reaching the policy objectives is very difficult to measure for several reasons, including the diversity of implementation approaches in Member States and lack of harmonized and integrated monitoring of impacts on soil threats and/or functions across the EU countries. The policy instruments are categorized according to their relevance and potential impact based on the legally adopted text into the following three categories.

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Table 22.2 Overview of policy clusters and instruments with relevance to soil threats Policy Instrument

Erosion

Floods & landslides

Salinization

Compaction

Loss of SOM

Biodiversity

Contamin. / Diffuse Pollution

Sealing

**

**

**

**

**

**

**

**

*

*

*

*

*

*

*

*

Overarching instruments Soil Thematic Strategy th

7 EAP Circular Economy Action Plan

**

Resource Efficiency Roadmap

**

**

H2020

*

*

*

*

*

*

*

*

LIFE + Program

*

*

*

*

*

*

*

*

CAP GAECs / Greening / RDPs

***

**

**

**

***

**

**

Forest strategy

*

*

*

*

*

Agriculture and forestr

Industrial (point source) contamination Environmental liability directive

**

***

Industrial emissions directive

**

***

Landfill directive

**

***

National emission ceiling directive

**

***

Waste framework directive

**

***

Mercury regulation

**

***

Cohesion fund

*

*

*

European regional development fund

*

*

*

State aid guidelines

*

*

*

Diffuse pollution and water management Water framework directive

**

***

**

**

***

Nitrates directive

**

*

**

**

***

**

**

***

Sewage sludge directive Nature protection, land and soil sealing Habitats and birds directives Biodiversity strategy

*** *

*

*

*

*

*

Soil sealing guidelines Floods directive

* ***

***

Environmental impact assessment directive

***

***

*

*

Climate and energy policy Adaptation strategy

*

Effort sharing decision

*

*

* **

LULUCF decision Renewable energy directive

*

* ***

***

*

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Soil Protection Policies in the European Union

(1) High ***: The instrument includes a binding, mandatory requirement that has the potential to address the deteriorating trend for a given soil threat; the requirement might be either explicit, directly addressing a soil threat, or implicit/indirect in the sense that meeting the instrument’s legal requirement requires addressing the soil threat. Although not binding in the strict sense (i.e. farmers do not have to receive the CAP payments), the CAP is included in this category because of its wide reach and economic importance for land management (e.g. in the case of CAP), or soil protection of national instruments that MS experts identified as relevant for soil protection are tied to the instrument. (2) Medium **: these instruments include explicit or implicit provisions for soil threats but these provisions are non-binding; alternatively, they are still in early stages so that their potential impact on a given soil threat remains limited. (3) Low *: these policy instruments are non-binding instruments and only indirectly (implicitly) address a given soil threat; they include, for example, awareness-raising, information exchange, monitoring, research or other funding which do not have binding targets for soil protection (e.g. minimum share of funding to address soil protection). If these instruments were binding or at least had binding targets for how widely they should be implemented, their potential impact could be higher.

22.3.1 Overarching Policies Since the Soil Framework Directive proposal was withdrawn, there is no single overarching document or a binding instrument at EU level that would require a holistic approach from Member States, such as is the case, for example, with the Water Framework Directive which sets out a framework for the management of water resources across the EU. Four EU level strategies and two funding instruments nonetheless set out some strategic provisions for soil protection (Table 22.3). These policies recognize that soil protection is of strategic importance in the EU. The Soil Thematic Strategy also lays out a strategic framework to address soil threats and functions in Europe. However, these policies are soft instruments, without a binding legal component. Their potential impact for addressing soil threats largely depends on the priority given to soil issues within the EU agenda and/or the extent to which Member States seek to emphasize soil when implementing sectoral policies and legislation. Given that other environmental objectives (water, air, biodiversity) have a stronger legal basis, these also receive more attention and

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soil protection is largely an additional outcome derived from protecting other environmental issues.

22.3.2 Agriculture and Forestry The Common Agricultural Policy (CAP) and the Forest Strategy are the two EU instruments dealing directly with the management of agricultural and forest land; however, their weight as a driver for land management decisions is very different. The Forest Strategy was adopted in 2013, setting out strategic guidance and the goal that Member States “ensure and demonstrate that all forests in the EU are managed according to sustainable forest management principles” by 2020. The Strategy allows for flexible interpretations of sustainable forest management in Member States and it is not accompanied by a legal component or prescriptive requirements. As such, the Forest Strategy has minor influence over soil protection in forest management in Europe, and most of the planning and policy action in this area taking place within Member States, framed by legislative requirements for water and nature management as they relate to forests. The CAP, on the other hand, is a funding and regulatory instrument which originated in 1962, and covers the majority of agricultural land, in recent decades also forest land. The CAP is a major economic driver behind land management decisions in the EU, accounting for over a third of the EU budget for the 2014–2020 budget/programming period. The CAP contains many different instruments and its complexity is compounded by the implementation choices that are given to Member States. It is also a contentious policy, criticized by environmental interests for its historical role as a driver behind the intensification of agricultural production in the EU and its current failure to deliver “public goods for public money”, or its failure to ensure that public funding supports sustainable agriculture and forestry (BirdLife International 2011). The CAP’s influence over the environment in the EU cannot be overstated, with some authors arguing that “it provides finances, policy mechanisms, and control systems with higher environmental impacts than all other policies and directives” (Pe’er et al. 2014). The structure of the CAP is broadly defined by its two Pillars: (1) Pillar 1 includes direct payments (including the “greening” payments) to farmers per hectare of land farmed, as well as some market focused measures. These measures are fully funded from the EU level. (2) Pillar 2 provides co-funding for Member State (and in some countries also regional) Rural Development Programmes (RDPs), which in turn offer a wide range of measures and payments (per hectare, investment and

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Table 22.3 Overarching EU policies for soil protection

Name of Policy

Key coverage related to soil protection

Soil Thematic Strategy

Recognizes all soil threats and suggests national / regional approaches to best deal with each threat; Four pillars for action are defined: awareness-raising, research, integration of soil protection issues in the design and implementation of national and EU policies, and a proposal for framework legislation for soil protection

7th Environment Action Plan (EAP) (Decision 386/2013/EU)

Promotes the implementation of environmental legislation that may contribute to the protection of natural capital e.g. habitats, biodiversity, air, water, and that tackle climate change, chemicals, industrial emissions and waste, which also ease the pressures on soil; Seeks the integration of soil related considerations in agriculture and forestry, i.e. greening of the CAP, renewable energy, and Member States’ planning decisions; EU and Member States are encouraged to reflect on the introduction of a risk-based approach within a binding legal framework (including a target) on soil

Roadmap to Resource Efficient Europe [COM (2011) 571]

Milestones are set for the protection of: ①natural capital, including the maintenance of soil fertility; ②water, including to support increased water retention in soils, and ③soil, including reducing soil erosion and loss of organic matter, and remedial work on contaminated sites; Identifies the need for further research on the supply of phosphorous for fertilization

Circular Economy Action Plan [COM (2015) 614]

Includes legislative proposals waste, which could contribute to reducing soil contamination, and on fertilizer and water reuse in agriculture, with the aim to reduce the input of contaminants to arable soils and promote the recovery of nutrients from local biomass

H2020 Research Programme and LIFE + Programme

These two funding programmes include budget for EU-wide research projects (H2020) as well as for applied conservation / environmental projects in specific countries. Both types of projects can be highly relevant to soil, however the outcomes for soil are dependent on the prioritisation of soil issues and within Member States

other payments) to address environmental and socio-economic issues in agriculture, forestry and rural areas more broadly. Among its three core objectives is also the sustainable management of natural resources, which integrates the CAP instruments that are of most relevance for soil protection (see Table 22.4): (1) Greening payments in Pillar 1; (2) RDPs under Pillar 2; (3) Standards for Good Agricultura l and Environmental Condition (GAEC) under the cross- compliance requirements. Some examples of the types of measures that can be funded by Rural Development Programmes are included in Box 22.2.

Box 22.2. Examples of soil protection measures funded by Rural Development Programs 2014– 2020 Erosion dams on arable land in Flanders, Belgium: Straw is used to create micro dams on arable soils prone to erosion. The flow of water and sediment from land further up the slope is slowed down, allowing the soil particles and sediment to settle in the dam as the water seeps through. This has the additional benefit of reducing the risk of soil erosion downstream of the dam because peak flows are capped. The dams are maintained in the same place for the duration of the five-year agri- environment-climate contract. Soil erosion control in Bulgaria: This sub- measure offers farmers a choice of erosion control measures for different farming systems including: conversion of

22

Soil Protection Policies in the European Union

arable land into permanent grassland using perennial grass mixtures; growing grass between the rows and/or building and maintaining protective run-off furrows across the slope in vineyards and permanent crops; establishing and maintaining buffer strips and/or crop rotation strips on arable land. Precision farming in Baden-Wurttemberg, Germany: Precision arable farming involves very specific, targeted soil and crop management within individual fields. It uses ICT-based sensor technologies and software to link in-field variables such as soil type and nutrient levels with farming practices such as tillage, seeding, and fertilizer, herbicide and pesticide applications, often carried out by computer guided machinery. Optimising inputs in this way helps to reduce the risks of soil pollution and compaction. The initial steps in precision farming require soil sampling and analysis of soil properties and nutrient content in sub-plots throughout the field. Maintaining lowland peat bogs in Scotland UK: The aim is to keep the bog surface (both the vegetation and the peat) as intact, undisturbed and as wet as possible. The plants that grow there such as Sphagnum mosses are adapted to wet conditions with limited nutrients, and they contribute to the active creation of peat and help to reduce flood risk by holding large volumes of water. Source: Frelih-Larsen et al. (2016). The benefits of these measures in the CAP can potentially be significant for soil protection, ranging from the preservation of soil carbon stocks under permanent grassland requirement or protection from soil erosion under GAEC and RDP measures. The RDP measures can offer very targeted support for soil protection over multiple years, and also measures with strong knowledge and awareness-raising component which can increase motivation of farmers for sustainable soil management. The flexibility that Member States have in defining obligations for greening payments and the GAEC standards, as well as the sort of measures that they fund under Rural Development Programmes is set up to allow the countries to make choices that are most appropriate to their farming systems, socio-economic priorities, and environmental conditions. This flexibility, however, makes it challenging to evaluate how the implementation of CAP contributes to environmental objectives, including soil protection since it results in a very complex picture of diverse approaches and specific measures1. Overall, the

1

For example, a total of 118 rural development programs are implemented in the EU in 2014–2020 period.

343

environmental performance of the CAP remains under criticism [see, for example, Pe’er et al. (2014)] and there are also limitations to keep in mind when considering CAP’s contribution to soil protection. Specifically, this includes the following points: (1) the current structure of the CAP allows much room for interpretation and flexibility for Member States, and few mandatory measures with high ambition for soil protection; for example, higher ambition for soil protection could be achieved by strengthening the GAEC standards (e.g., the GAEC 6 standard for soil organic matter could be further clarified to include the requirement to incorporate crop residues, and an additional standard to protect organic rich soils introduced [this standard had already been proposed, but later removed in the negotiations for the last CAP) reform]. (2) the complexity of the CAP makes it difficult to monitor and its impacts are difficult to evaluate. (3) the share of the CAP funding available for targeted and ambitious measures within Rural Development Programmes is limited compared to the Pillar 1, and within the RDPs, investment for sustainable resource management can also be limited due to the flexibility and the ambition that Member States show for environmental protection (e.g. a recent review of RDPs focused on the integration of water concerns in the RDPs showed that this can range from 80% allocated to sustainable resource management to only 25% of the available RDP budget (Rouillard and Berglund, 2017). (4) whereas the greening measures, GAECs and RDP measures have potential for soil protection, the absence of a binding legislative framework for soils means that there is no legal requirement for ensuring that these measures work well together and address the soil threats a given country or region in a coherent and synergistic manner. Therefore, while the CAP is a key policy instrument for management of agricultural soils in Europe, its actual impact on sustainable soil management in the EU is difficult to assess and its overall contribution to delivering ecosystem services is not optimized and inconsistently delivered across Europe.

22.3.3 Industrial (Point Source) Contamination of Land The EU has developed several instruments dealing with preventing, limiting and remediating industrial and point source contamination (Table 22.5), a significant soil threat in Europe with an estimated 2.5 potentially contaminated sites

344 Table 22.4 Instruments in Common Agricultural Policy most relevant to soils

A. Frelih-Larsen and C. Bowyer Name of CAP instrument

Key coverage related to soil protection

Greening payments in pillar 1

Making up 30% of all direct payments, greening payments are annual payments, on top of basic payments, which are given for mandatory practices followed by farmers and including: crop diversification; protection of permanent grassland, and ecological focus areas (EFAs); There is flexibility at Member State level on how crop diversification and EFA obligations are defined; and some flexibility for farmers in how they implement these obligations. EFAs can include, for example: fallow land, terraces, buffer strips, areas with short rotation coppice, areas with catch crops, nitrogen fixing crops

Rural development programs

Two of 18 focus areas for RDPs focus on soil protection: ①focus area “4C preventing soil erosion and improving soil management”; and ②focus area “5E fostering carbon conservation and sequestration in agriculture and forestry”; Of the wide range of 19 measures that are available to Member States the most relevant for soil protection include: agri- environment-climate measure which offers multi-annual payments for sustainable soil management practices, knowledge actions and farm advisory services, investments in physical assets, Natura 2000 and Water Framework Directive payments (to farmers affected by nature and water legislation), payments for organic farming, and cooperation measure which supports cooperation among farmers

GAEC standards under cross- compliance

Three explicit soil and carbon stock GAECs include: GAEC 4-Minimum soil cover; GAEC 5-Minimum land management reflecting site specific conditions to limit erosion; and GAEC 6-Maintenance of soil organic matter level through appropriate practices including a ban on burning arable stubble, except for plant health reasons; Moreover, GAEC 7-Retention of landscape features-can help to limit soil erosion and maintain/improve soil organic matter content; and GAEC 1-establishment of buffer strips along watercourses-protects from soil erosion along water courses

and 340,000 sites likely to be contaminated and in need of remediation (EEA 2014). The most frequent contaminants are mineral oils and heavy metals, and the key cause are municipal and industrial waste disposal and treatment, as well as metal industries, petrol stations, and mining. The policy interventions relating to contamination include, on the one hand, preventive action to control activities generating pollution now and potentially in the future; and on the other hand remediation of contamination that already exists on land and in soils. Several regulatory initiatives are in place in the EU to control high risk activities or contaminants preventing release, limiting emissions or remediating damage. Moreover, the Emissions Ceiling Directive (NECD) offers some environmental quality standards for land. The following table shows these instruments and how they relate to soil protection. The policies in place offer relatively strong provisions for controlling specific high-risk activities and substances, both for preventing emissions and requiring remediation should contamination occurs. The legislation requires permitting, monitoring and reporting systems at national level. Moreover, the Water Framework Directive, and its related Directives (Groundwater and Priority Substances Directive) also set thresholds for the presence of pollutants in waters,

which also imposes limits on emissions from industrial facilities. A limitation of the above policies is that they address and manage pollution activities occurring from their date of entry into force. This means that there is no mechanism in place in the EU to identify and deal with historic contamination resulting from industrial production sites in place before 1996 (when IPPC Directive, the precursor of IED came into force). The identification and remediation of historically contaminated sites has been dealt with at the level of Member States. Nonetheless, some limited funding opportunities are available at the EU level via the Cohesion Fund and the European Regional Development Fund to support the identification of sites, as well as for remediation of historic contamination where the liable party cannot be held responsible.

22.3.4 Diffuse Pollution and Water Management The EU has in place a range of policies to address diffuse pollution to the environment broadly, as well as to control diffuse pollution which affects water quality more

22

Soil Protection Policies in the European Union

Table 22.5 Industrial (point source) contamination policies

345

Name of policy

Key coverage related to soil protection

Environmental Liability Directive (ELD)

Focuses on local emissions of pollutants that change the status of land, water and biodiversity, and intended to reduce incidents as well as ensure remediation of emissions to land and water

Industrial Emissions Directive (IED)

Focuses on local emissions of pollutants that change the status of land, water and biodiversity, and intended to reduce incidents as well as ensure remediation of emissions to land and water

Landfill Directive (LD)

Includes provisions for containment that protect soils; it is relatively easy to determine compliance for regulated landfills. There is considerable non-compliance in some MS which means that soils remain at significant risk; and containment is, itself, a form of sealing

Waste Framework Directive

Contains clear provisions for the operation of waste management facilities, taking account of soil protection; Standards may be set by Member States to protect soil, however it is not clear if such provisions have been taken into account at in Member States’ regulatory decisions

National Emission Ceilings Directive (NECD)

Covers all key acidifying and eutrophying substances affecting soil functions and sets national limits on emissions based on how much impact they have on soils; There is some remaining non-compliance, the Nox emissions need further reductions, and addressing ammonia emissions faces significant problems

Mercury Regulation

Deals with the question of the management of facilities managing, storing and disposing of mercury in the EU it also currently prohibits the export of mercury outside the EU; it also deals relatively robustly with the question of potential isolated emissions of mercury at the facility level and makes close links to other EU policy. It seeks limit mercury on the market, hence acting as a limit on likely incidents of pollution

Cohesion Fund, European Regional Development Fund (ERDF), State Aid Guidelines

Cohesion Fund and ERDF provide a potential opportunity to provide funding to improve soil status both through addressing contamination and through ‘promoting protecting and restoring biodiversity and soil and promoting ecosystem services. ERDF also promotes urban brownfield decontamination and other actions that may reduce soil contamination specifically in urban areas; State aid guidelines permit action to remediate contaminated land, in particularly problematic cases i.e. where the liable party cannot be identified or held liable

specifically (Table 22.6). Diffuse pollution can result from agricultural practices (due to application of fertilizers and pesticides), or be linked to urban pollution (e.g., inputs from roads) or deposition of pollutants from the atmosphere. It could also result from specific, dispersed, sites such as uncontained landfills or poorly managed industrial sites. Table 22.6 shows how the regulatory instruments aim to regulate activities interacting directly with soils and prevent or minimize soil (and water) diffuse pollution.

Overall, the instruments dealing most specifically with diffuse pollution are aimed at protecting water. Policies in the cluster on industrial (point source) contamination also contribute to controlling diffuse pollution (by setting limits on emissions). The very broad scope of the Water Framework Directive and extensive provisions that it contains for tackling diffuse pollution to water, but also issue related to water quantity, make this policy one of the most important instruments also

346 Table 22.6 Diffuse pollution and water management policies

A. Frelih-Larsen and C. Bowyer Name of policy

Relevance to soil protection

Sewage Sludge Directive

The directive sets clear standards for quality of sewage sludge applied to soils, these standards are achievable, and lead to controlling soil and water pollution from this source

Water Framework Directive (WFD) and related directives (Groundwater Directive and Priority Substances Directive)

Aims to achieve a good status for all European Union waters by establishing a framework for the protection of inland surface waters, transitional waters, coastal waters and groundwater; The WFD does not explicitly address soil protection. However, the directive addresses agricultural activities, which are a major cause for pressures on water and at the same time are associated with soil threats. For example, nutrient and pesticide loads are linked to soil contamination (e.g. with pesticides) and loss of soil biodiversity, soil salinization (e.g. through abstraction practices in coastal areas leading to potential salinization of groundwater through seawater intrusion), and poor soil drainage. Hence, achieving the directive’s objectives requires (among other measures) the implementation of soil management measures which contribute to soil protection

Nitrates Directive (91/676/EEC)

Aims to protect surface waters and groundwater against pollution by nitrates from agricultural sources. It requires Member States to identify Nitrate Vulnerable Zones and set up action plans for these zones. The Directive promotes a voluntary code of good agricultural practices. While it does not have explicit soil-focused objectives, it involves the use of soil management measures to reach its aim, such as the use of cover crops or crop rotations. These measures increase the amount of soil organic matter and improve soil structure; thereby they reduce the potential for soil erosion and the related run-off and leaching of nitrates. Further measures include an appropriate fertilization balanced according to timing, crop needs, climate, etc.; and restrictions on application periods or levels of fertilizer in the NVZ. This could reduce traffic as well as stocking rates and therefore decrease the risk of soil compaction. Reducing the use of fertilizer can also reduce diffuse soil contamination

for soil protection in the EU. However, there are limits in the form of poor implementation by Member States and, at the end of the day, if measures protect water, that is sufficient since its policy objectives are based on status of water bodies. Good chemical status of waters and levels of soil contamination are not always clearly related, and while soil protection may be a side effect, it is not a specific objective.

22.3.5 Nature Protection, Land Use Planning and Soil Sealing The EU has put in place legislation to prevent, limit, mitigate or compensate pressures on the natural environment and land and its impacts on soil. This covers pressures from activities, plans or programs linked to development

22

Soil Protection Policies in the European Union

operations; and changes in land use linked to agricultural, forestry, transport etc activities. Seven EU policies include priority measures linked to pressure on nature and land use. These include regulatory instruments focused on ensuring the protection of habitats and species, determining whether projects or plans/programs have environmental implications on soil, and providing a framework approach to flood risk management, as well as Soil Sealing Guidelines and the Biodiversity Strategy (Table 22.7). The policies in this thematic area indirectly contribute to protection of soils. The Habitats and Birds Directives establishes a framework for the protection of biodiversity in the whole EU, which may indirectly contribute to addressing a number of soil threats through the protection and restoration of semi-natural and natural habitats. The EIA and SEA Directives establish a legislative framework for assessing the environmental impacts of projects (EIA) or plans and programs (SEA). The lack of mandatory requirements related to soils is a weakness for achieving soil protection objectives via these policies. None of the legislative instruments’ core goals deal primarily with soil protection, such as is the case with the Habitats or Birds Directives. Where the instrument is primarily focused on soil-such as in the case of the Soil Sealing Guidelines-it is non-binding by nature. Where an instrument has direct implications on certain aspects of soil protection-such as the EU Floods Directive- it does not set any specific soil-related requirements. This means that the relevance to soils is dependent on the willingness of Member States to adopt soil- relevant measures; this is determined in turn by the implementation process put in place by Member States and/or their willingness to go beyond the requirements set out in the EU law.

22.3.6 Climate and Energy Policy The EU has put in place a number of policies focused on climate change mitigation and adaptation. The current policy coverage with relevance to soils includes the instruments outlined in Table 22.8. These focus on the period up to 2020. It should be noted, that there is the potential for a shift in the coverage and relationship with soil protection driven by the development of proposals for the post 2020 on climate and energy. There may be opportunities linked to proposals to further regulate emissions from Land Use and Land Use Change and Forestry (LULUCF). In all of the above instruments soil protection is not the ultimate goal of the policy, however, addressing soil protection can contribute to the policy delivering its objectives. Since the treatment of agricultural emissions within the EU’s GHG “effort sharing” policies and LULUCF are currently under review, their importance as drivers of land

347

management could increase with time; this will depend on the level of targets set and proposals to “transfer” emissions between LULUCF and the effort sharing sectors to offset emissions in the latter via the former. An emphasis on improved soil carbon management to deliver climate related goals would be beneficial for soil protection overall since changes to nutrient management and improvements in soil organic matter often address multiple pressures and threats experienced by soils, and can have wider societal and environmental benefits. Management of forest and agricultural soils are key to delivery of LULUCF goals, as noted by Member States reports under Article 10 of requirements looking at approaches to LULUCF implementation (Paquel et al. 2017). A potential limitation here is the need to integrate soil carbon management actions in other policy fields, particularly those that directly drive changes in management practices, for example, through the CAP or requirements to manage soils for water protection. In the absence of defined EU level goals and needs for soil protection, there is a risk that actions on soil protection may be over looked unless there is a binding target related to soil carbon management.

22.4

Conclusion

There are some examples where EU level law and polices have been successful in addressing soil threats. Specifically, in the combating of industrial and point source contamination, largely through the regulation of industry and waste management, EU law is in place aimed at preventing future incidents, reducing their severity and ensuring that the polluter pays i.e. that responsibility and liability for the cleanup is established. There do, however, remain gaps in terms of the treatment of historical contamination and contaminated sites. Overall there is an absence of a clear policy baseline in the EU for soil protection and the delivery of healthy soils. Ideally a clear EU level, binding policy would set out goals, objectives and targets for soil protection, as well as monitoring requirements; in the absence of this the EU collectively has no clear and consistent basis on which to build a holistic soil protection policy and ensure the integration of soil concerns in other policy areas. No clear definition exists on what should be achieved when protecting soils, i.e. what should a soil deliver, what should a soil’s integral environmental value and value to society be in Europe, what should be monitored? Soil protection action is, therefore, lacking a frame which would ensure mainstreaming of soil concerns in other policies, for example, by ensuring that sufficient efforts are placed in research or LIFE++ projects, or that the Common Agricultural Policy (CAP) has GAEC standards for soil protection that are sufficiently strong, their effects

348 Table 22.7 Nature protection, land use planning and soil sealing policies

A. Frelih-Larsen and C. Bowyer Name of policy

Relevance to soil protection

Habitats Directive (2007/60/EC)

Member States are required to designate protected areas in Natura 2000 network (Sites of Community Importance and Special Areas of Conservation) as well as carrying out of conservation measures (such as extensive farming) or achieving the coherence of the Natura 2000 network. This might contribute to reduce local soil contamination, erosion, compaction, protect soil organic matter and soil biodiversity. Protection of Natura 2000 sites from development also prevents soil sealing at least in Natura 2000 sites

Birds Directive

Member States are required to designate special protection areas and carry out of conservation measures to achieve favorable status of habitats and species. This might contribute to reducing soil threats and lead to restoration of habitats

EU Biodiversity Strategy 2020 (COM (2011) 244)

Actions and conservation measures under Targets 1, 2, 3 and 6 should contribute to limit soil compaction, acidification, contamination, loss of soil biodiversity, loss of soil organic matter, erosion and flooding

Environmental Impact Assessment Directive (2001/42/EC), and Strategic Environmental Assessment Directive (92/43/EEC)

As cross-sectoral pieces of legislation, the IEA and SEA Directive reference to a wide number of areas including agriculture, forestry, industrial pollution, water, waste, energy and climate; Both directives require a description of the factors likely to be significantly affected by projects including likely impacts on all soil threats; In defining less harmful alternatives in case a project is likely to affect soil quality, project developers are free to select the most suitable measures to ensure high level of soil protection. For programs or plans, Member States can decide to select appropriate remedial actions to protection soil, in response to any likely significant effects on the environment of implementing a plan or a program

Floods Directive (2007/60/EC)

Aims to reduce and manage the risks that floods pose to human health, the environment, cultural heritage and economic activity; It requires Member States to identify flood risk areas, map them and establish flood risk management plans. While not explicitly addressing soil protection, some of the measures that reduce flooding risk can contribute to soil protection, in particular, measures that increase water infiltration and retention capacities of soils. For example, the Floods Directive may lead to the promotion of green infrastructure and land use planning rules to control run-off and pluvial flooding. This, in turn, can reduce soil sealing. The directive implementation can also promote protection of soils by preventing the urbanization of floodplain and riparian land; Since the measures are not mandatory, actual beneficial impacts on soils depend on interest and the willingness of competent authorities to implement measures beneficial for soils

Soil Sealing Guidelines [SWD(2012) 101]

The Guidelines explicitly focus on limiting, mitigating and compensating for the effects of soil sealing. A wide number of best practices are proposed

monitored, that rural development programs target soil protection in an ambitious way, and the CAP instruments as a whole are designed in a complementary way. This is in stark contrast to the situation in the field of water management where the legal basis in the Water Framework Directive and other water legislation means that water protection provisions can be integrated, cross

referenced and reinforced in measures such as Industrial Emissions Directive, Environmental Liability Directive or also the Common Agricultural Policy. This risks the deprioritization of soil issues due to a lack of a clear, consistent position at EU level. Within Europe, and globally, there is a mounting interest in soils ability to support the delivery of other environmental

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Soil Protection Policies in the European Union

Table 22.8 Climate change and energy policies

349

Name of policy

Relevance to soil protection

EU Adaptation Strategy [COM(2013) 216 final]

provides an overarching framework with the aim to increase adaptation through different voluntary mechanisms that enhance the preparedness and capacity to respond at different levels to climate change effects

Effort Sharing Decision (Decision No 406/2009/ EC on the effort of Member States to reduce their greenhouse gas emissions to meet the EU greenhouse gas emission reduction commitments up to 2020)

It sets out the targets for greenhouse gas (GHG) emission reductions for each Member State from sectors outside the EU Emissions Trading Scheme (transport, agriculture, buildings, small industry and services sectors). It links to soil protection because of the connection between soil management and GHG emissions associated with agriculture

Decision on accounting rules for GHG emissions and removals relating to land use, land-use change and forestry (LULUCF Decision No 529/2013/EU)

It sets out an obligation for Member States to provide information on their LULUCF actions to limit or reduce emissions and maintain or increase removals, with reporting and accounting only required for certain categories of emissions. However, at present LULUCF emissions and removals do not contribute to the EU’s 2020 emission reduction target. Reporting on changes in emissions relating to soil organic matter increase the evidence base and understanding of actions needed to protect soils

The Directive on the promotion of the use of energy from renewable sources (2009/28/EC, RED Directive)

All renewable energy expansion, if it implies land take or change in land management, has a potential impact on soil protection. However, the RED is most relevant to soil in the context of the expansion in bioenergy and biofuel targets. The RED contains sustainability criteria that relate to protecting certain valued land areas based on high carbon or high biodiversity value that would potentially link to soil protection goals. Moreover, it contains specific provisions to support use of degraded land for biofuel feedstock cultivation

goals; not least contributing to climate mitigation ambition through the sequestration and retention of soil carbon. In addition, under the SDGs there is a commitment to deliver land degradation neutrality and report on that achievement. Europe’s lack of a clear position and consistent basis for soil protection means its ability to deliver holistic soil management that supports these international commitments is also hindered. Moreover, the lack of a coherent and integrated framework risks that soil protection might become further segmented and overly focused on achieving one outcome. As noted in the introduction a key characteristic of soils is their interaction with other elements of the environment and delivery of benefits for multiple actors; this multiplicity of outcomes risks being ignored by EU policy if the status quo remains unchanged, missing also opportunities that a more holistic management might deliver.

References BirdLife International (2011) CAP disappoints on green hopes, Press Release, 12 October. www.birdlife.org/community/2011/10/capdisappoints-on-green-hopes. Accessed 16 April, 2020 Bowyer C, Withana S, Fenn I, et al (2008) Land Degradation and Desertification. European Parliament. http://www.europarl.europa. eu/RegData/etudes/etudes/join/2009/416203/IPOL-ENVI_ET (2009)416203_EN.pdf. Accessed 16 April, 2020 EEA (European Environment Agency) (2007) Celebrating Europe and its environment, marking the 50th anniversary of the Treaty of Rome. https://www.eea.europa.eu/environmental. Accessed 16 April, 2020 EEA (European Environment Agency) (2010) Major Soil Types in Europe, December 2010. https://www.eea.europa.eu/data-andmaps/figures/the-major-soil-types-of-europe. Accessed 16 April 2020 EEA (European Environment Agency) (2014) Progress in management of contaminated sites (CSI 015/LSI 003)-EEA Indicator for soil

350 contamination. European Environment Agency, Copenhagen. https://www.eea.europa.eu/data-and-maps/indicators/progress-inmanagement-of-contaminated-sites-3/assessment. Accessed 16 April 2020 EEA (European Environment Agency) (2015) The European environment–state and outlook 2015: Synthesis report. European Environment Agency, Copenhagen. https://www.eea.europa.eu/soer-2015/ synthesis/report. Accessed 16 April 2020 European Commission (2012) Report from the Commission to the European Parliament, The Council, The European Economic and Social Committee and The Committee of the Regions. The implementation of the Soil Thematic Strategy and ongoing activities, 13.2.2012, COM (2012) 46 final. http://eur-lex.europa.eu/ legal-content/EN/TXT/PDF/?uri=CELEX:52012DC0046&from= EN. Accessed 16 April 2020 European Commission (2014) Withdrawal of Obsolete Commission Proposals. 2014/C 153/03, 21.5.2014. https://ec.europa. eu/dorie/fileDownload.do;jsessionid=b6cl1XOgZPQJ_ HcfSMn13Kk_2wXwXj3TR4tbrz7Mzm-E9ga7Zmpj!-898031139? docld=1730066&cardld=1730065. Accessed 16 April 2020 European Commission (2017) Europa, Guide to EU treaties, EC extracted Oct 2017. https://europa.eu/european-union/law/treaties_ en. Accessed 16 April 2020 European Community (1973) Declaration of the Council of the European Communities and of the Representatives of the Governments of the Member States, Meeting in the Council of 22 November 1973 on the Programme of Action Of The European Communities On The Environment, Official Journal Reference, No C 112/1. http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/? uri=OJ:C:1973:112:FULL&from=EN. Accessed 16 April 2020 European Community (1987) Treaties Establishing the European Communities, Treaties amending these Treaties, Single European Act, Resolutions and Declarations, Office for Official Publications of the European Communities. https://europa.eu/european-union/ sites/europaeu/files/docs/body/treaties_establishing_the_european_ communities_single_european_act_en.pdf. Accessed 16 April 2020 European Union (2002) Decision No 1600/2002/EC of the European Parliament and of the Council of 22 July laying down the Sixth

A. Frelih-Larsen and C. Bowyer Community Environment Action Programme, 10.9.2002 Official Journal of the European Communities, L 242/1. http://eur-lex. europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX: 32002D1600&from=EN. Accessed 16 April 2020 European Union (2013) Decision No 1386/2013/EU of the European Parliament and of the Council of 20 November 2013 on a General Union Environment Action Programme to 2020 ‘Living well, within the limits of our planet’, Official Journal of the European Union, L354/171, 28.12.2013. http://eur-lex.europa.eu/legalcontent/EN/TXT/PDF/?uri=CELEX:32013D1386&from=EN. Accessed 16 April 2020 Farmer AM (2012) Manual of European Environmental Policy. https:// ieep.eu/uploads/articles/attachments/74389e41-868c-4906–9bdc3f04addd0bf0/1.5_Environment_in_the_treaties_-_final.pdf?v= 63664509873. Accessed 16 April 2020 Frelih-Larsen A, Bowyer C, Albrecht S, et al (2016) Updated Inventory and Assessment of Soil Protection Policy Instruments in EU Member States. Final Report to DG Environment. Berlin, Ecologic Institute. http://ec.europa.eu/environment/soil/pdf/Soil_inventory_ report.pdf. Accessed 16 April 2020 Grieger A (2012) Only one earth: stockholm and the beginning of modern environmental diplomacy. Environ Soc Portal Arcadia 2012 (10):2020. https://doi.org/10.5282/rcc/3867. Accessed 16 April Paleari S (2017) Is the European Union Protecting Soil. A critical analysis of community environmental policy and law. Land Use Policy 63:163–173 Paquel K, Bowyer C, Allen B, et al (2017) Analysis of LULUCF actions in EU Member States as reported under Art. 10 of the LULUCF Decision for the European Commission, London, IEEP Pe’er G, Dicks LV, Visconti P et al (2014) EU agricultural reform fails on biodiversity: extra steps by Member States are needed to protect farmed and grassland ecosystems. Science 344(6188):1090-1092 Rouillard JJ, Berglund M (2017) European level report: key descriptive statistics on the consideration of water issues in the Rural Development Programmes 2014–2020. European Commission, Brussels, Belgium. http://ec.europa.eu/environment/water/pdf/EU_ overview_report_RDPs.pdf. Accessed 16 April 2020

Soil Conservation Programmes and Policies in England and Wales

23

Jane Rickson and Michael Fullen

23.1

Introduction

Soil conservation programmes and policies are justified by evidence of soil degradation processes and their negative impacts on natural capital. The last national survey of the state of soil resources in England and Wales was carried out in the 1980s. Whilst smaller scale monitoring has been continued [e.g. National Soil Survey Resurvey (SSLRC 1996); Countryside Survey (Norton et al. 2012)], these surveys covered fewer sites and in the case of the Countryside Survey the only direct measure of soil degradation (as defined by the EU Thematic Strategy for Soil Protection) was change in soil carbon. This chapter presents the evidence on the extent and severity of the different processes of soil degradation, with emphasis on soil erosion by water. The economic, environmental and social impacts of these processes in England and Wales are also discussed. The effects of soil degradation are of sufficient concern that a number of soil conservation programmes and policies at different spatial scales have been designed and implemented in England and Wales. Their purpose is to control soil degradation processes, mitigate their detrimental effects and restore land affected by soil degradation. The ultimate aim is to ensure healthy soils are able to function and deliver a range of ecosystem goods and services of value to society.

23.2

Soil Degradation Issues in England and Wales

23.2.1 Processes Involved According to European Commission’s Thematic Strategy for Soil Protection (2006), degradation processes that threaten soil resources include: ① soil erosion; ② organic matter decline; ③ compaction; ④ salinisation; ⑤ landslides; ⑥ contamination; ⑦ soil sealing; ⑧ loss of soil biodiversity. These, with the exception of salinisation and landslides, were identified sources of soil degradation in the UK Government’s Soil Strategy for England (Defra 2009). Whilst soil degradation is not currently as problematic in England and Wales as it is in other countries, the rates and impacts of degradation processes can still be significant (Posthumus et al. 2011). Although these processes are discussed separately in the following sections, it should be noted that soil degradation processes are often inter-related. Soil erosion and compaction, for example often occur on the same site, sharing similar causes and generating similar effects. Compaction by heavy farm machinery can increase surface runoff, leading to soil erosion. Loss of soil organic content and soil biota may reduce aggregate stability, increasing the risk of both soil erosion and compaction. 1. Soil erosion in England and Wales

J. Rickson (&) School of Water, Energy and Environment, Cranfield University, Cranfield, UK e-mail: j.rickson@cranfield.ac.uk M. Fullen Wolverhampton University, Wolverhampton, UK

Soil erosion is a universal process that involves the detachment and transport of soil particles or small aggregates by erosive agents (primarily rainfall, runoff, subsurface flow and wind). Owens et al. (2006) also considered the loss of soil through tillage erosion, and co-extraction on farm vehicles and harvested crops (Table 23.1). Most studies in England and Wales have focused on soil erosion from agricultural land (Table 23.2), with relatively little attention paid to soil erosion caused by construction, infrastructure, industry (other than agriculture), recreation or tourism activities.

© Science Press 2022 R. Li et al. (Editors-in-Chief), Global Degradation of Soil and Water Resources, https://doi.org/10.1007/978-981-16-7916-2_23

351

352

J. Rickson and M. Fullen

Table 23.1 Comparison of the magnitude of soil loss for different erosion processes in England and Wales (Owens et al. 2006) Wind

Tillage

Co-extraction with root crops and farm machinery

Water

Typical erosion rate range/[Mg/ (ha a)]

0.1–2.0

0.1–10.0

0.1–5.0

0.1–15.0

Land use affected

Arable, upland, some pasture

Arable

Arable

Arable, pasture, upland

Exported off field

Yes

No

Yes

Yes

Table 23.2 Water erosion monitoring schemes in England and Wales—monitoring bodies, years monitored, number of localities monitored, areas (km2) of arable land monitored and range of rates (from Evans 2005)

Monitoring organisation

Period of scheme monitored

Number of localities

Range in mean area of arable land in monitored localities/km2

Mean total arable area monitored year 1/km2

SSEW

1982–1986

17

28.1–95.4

708.4

ADAS

1989–1994

13

0.3–2.8

11.3

SSLRC

1996–1998

257

JB

1982–2002

1

(0.1–1.8)*

(7.9)*

0.08–0.1

25.7 36.0

SSEW Soil Survey of England and Wales; ADAS Agricultural Development and Advisory Service; SSLRC Soil Survey and Land Research Centre; JB John Boardman * The areas monitored were smaller in extent in 1989

“England is generally not associated with high rates of soil degradation, but the combination of rainfall, soil type, slope properties and land management can result in unacceptable losses of soil and associated nutrients, with adverse impacts on receiving waters” (Posthumus et al. 2011). Table 23.3 shows some examples of measured soil erosion rates for soil/land use combinations. The figures shown are not dissimilar to those quoted in Defra’s (Department of Environment, Food and Rural Affairs) Soil Strategy for England Supporting Evidence paper (Defra 2009). “Erosion is a major issue. In the 2007 Farm Practices Survey for England, farmers assessed the extent of soil erosion on their farms. In all, 50% of farmers stated that they had experienced some indicator of soil erosion on their land-indicators included discoloured runoff entering ditches and water courses, sediment deposited in ditches and water courses, sediment deposited on roads and formation of gullies and rills (http:// statistics.defra.gov.uk/esg/publications/fps/default.asp). Typical soil erosion rates are in the order of 20

1.2–1.5

25–28

0.5–2.8

32

0.85– 1.15

–

20–25

0.09– 0.72

9

17–20 3–9

0.44 0.02

–

6

480

O. I. Bazhenova et al.

Fig. 30.3 Multi-annual dynamics of ablation and accumulation of loose material on the slopes of southern (1), northern (2) and western (3) exposures in the Onon-Argun steppe (Bazhenova et al. 1997)

from the cultivated slopes of the Presalairskaya plain for 120 years, approximately 9 cm of the humus-accumulative horizon was washed away. The minimum soil loss (8.1 cm) is in the Suzunskii, and the maximum (11.7 cm) in the Iskitimskii rayon. The thickness of the washed-out layer of slope soils of the Ob region during their agricultural use is approximately the same (8.4 cm), but the distribution area of washed-out soils in the Ob region is exactly 3 times less than in Presalairye. Annually lost soil mass from 1 hectare of weakly washed chernozems and dark gray podzolized soils varies within quite narrow limits—5.7–7.1 tons. On the medium-eroded soils, the washing out varies even more widely—12.9–16.5 t/(ha a). Annual erosion of soil mass on heavily eroded chernozems exceeds 20 t/ha. Within the Priobye and Presalairye, where the intensive anthropogenic impact on the soil cover is estimated for dozens of years (after the massive development of virgin and fallow lands), the average annual washout of soils does not exceeds 8.1–11.6 t/ha. Simultaneously with the erosive removal of the soil mass during the intensive land use, there are significant losses of humus soils. From each hectare of weakly washed-out soils with solid runoff products 540 kg of this substance have already been washed out. The humus loss in the medium-eroded soils is 2 times higher (approximately 900–1400 kg/ha), some of the washed-out material accumulates on the downslope aprons, forming soils with high humus content, the proportion of such soils is very small (2–3%).

30.3.3 The Intensity of Soil Loss from Arable and Pasture Lands of Eastern Siberia In most river basins in the south of Eastern Siberia, the sediment runoff is usually less than 20 tons per km2, the average density of gully dismemberment does not exceed 0.05 km/km2, and the erosion of arable land averages 5-10 t/ (ha a). In the Baikal region 20-60 m3/ha of soil is washed off depending on the cultivation type on the slopes of 4°–6°, and on slopes higher than 8°—60–190 m3/ha (Bychkov 1992). In the Onon–Argun steppe, on plowed slopes with a steepness of 3°–5o during strong downpours, the amount of soil removal from the field can reach 240 m3/ha. A dense network of rill wash up to 30 cm deep and 150-200 m long is formed. In the Nazarovskaya depression, where arable land is located on long slopes up to 5°–7° and plowing is often carried out along the slope, the amount of eroded soil fields is 140-175 m3/ha). The plowing along the contours of the relief weakens the washout intensity almost fourfold. The soil loss rate in pasture lands according to field observations for the period of 7–12 years in the Nazarovskaya and Yuzhno–Minusinskaya depressions varies from 0.2 to 3.1 mm/a. In the Western Baikal region in pasture cattle breeding areas (the Bugul’deika river basin), the soil loss rate on slopes of 10°–40°, calculated by the thickness of diluvium, formed during the period of agricultural development (240 years), is 0.4–0.7 mm/a. Similar rates of soil degradation in pastures were also obtained in the Barguzinskaya, Torskaya and Mondinskaya hollows.

30

Soil Erosion on the Agricultural Lands of the…

In the south of Siberia, as a result of economic development, not only has the soil loss intensity increased, but also the area of process development significantly expanded and included the taiga areas. Anthropogenic factors contributing to the soil erosion, in addition to agricultural activities also include forest fires and deforestation. Only in the Baikal region, as a result of industrial forest exploitation, 2,500,000 ha of forest were logged. In areas of intensive forestry development of the South-Eastern Baikal region (along the eastern coast of Lake Baikal), the annual removal of fine earth due to washing-out and linear erosion is 200– 600 t/km2.

30.4

Territorial Distribution of Soil Erosion

In order to prevent further degradation of land resources in the south of Eastern Siberia, it is necessary to develop land-use policies based on land zoning according to the degree of erosion hazard. We carried out such zoning for all the main agricultural areas of the south of Eastern Siberia (the Nazarovskaya, the territory of Russia (Larionov 1984). Applying this empirical dependence to determine the average annual soil loss rate in the southern regions of Siberia is confirmed by the data of full-scale measurements of the slope washout rate (Bazhenova 1993). The correlation coefficient of the measured and calculated rates is rather high (0.86 ± 0.11). At the first stage of the evaluation, we calculated the numerical values of factors entering into the dependence: A ¼ R  Kc  P  C where, A is the washout module from the rainwater runoff, t/ (ha a); R is erosion index of rainfall; P is erosion potential of the relief; Kc is coefficient of soil erodibility per unit of erosion index of precipitation; C is soil protection coefficient of vegetation cover and agrotechnics.

30.4.1 Erosion Hazard of Rains The main soil loss in the south of Eastern Siberia is accounted by for the period of rainfall. The indicator of erosion hazard of rains is the erosion index of precipitation (R), which represents the sum of the productions of kinetic energy of rains at their maximum intensity (Larionov 1984). To determine the index, we elaborated pluviograms of rains with a layer of 10 mm for 63 weather stations in the south of Siberia for a period of 20–75 years (Bazhenova et al. 1997).

481

Based on the calculations, a map of the distribution of the mean annual values of R, determined by the 30-min intensity of rain, is compiled (Fig. 30.4). It shows that in the southern regions of Siberia Kanskskaya and Yuzhno–Minusinskaya depressions, the average annual values of R30 vary from 1.5 to 15.3, i.e. the Irkutsk–Cheremkhovo plain, and the Selenga River basin). Quantitative assessment of soil erosion and mapping of erosion-hazardous lands in the south of East Siberia was carried out using the Universal Soil Erosion Equation (Wischmeier and Smith 1978), modified by the Laboratory of Soil Erosion and Channel Processes of Moscow State University for tenfold. In general, there is an increase in the erosion hazard of showers from northwest to southeast in accordance with the increase in the climate continentality and the increase in the proportion of rainfall in their total number (see Fig. 30.4). If the values of the index in the northwest are 3–4, then in the southeast of the Transbaikalia they increase twofold and reach 9. On the general background, the Baikal anomaly of R30 distribution is clearly distinguished, expressed in the related submeridional minimum of the indicator, on the one hand, traced from the island of Ol’ khon and Priol’ khonye (in the settlements of Sarma and Uzura R30 is 1.5) to the northern part of Lake Baikal and further to the northeast, and in the sublatitudinal maximum of R30, on the other hand, observed south of the lake on the Tankhoiskaya plain and the northern slope of the Khamar-Daban ridge. The average long-term values of R30 are 12-13 here (the weather stations of Tankhoi and Vydrino) and even 15 (Khamar-Daban), and the maximum over 40 years exceed 50 (Vydrino). The dry steppe bottoms of some intermontane and intramountain depressions, such as Minusinskaya, Kanskaya, Khemchikskaya, Shaganorskaya, Barguzinskaya and others, are characterized by a low erosion hazard (see Fig. 30.4). From the arid center of the depression where the values of R30 are 2, and sometimes less, the erosion index of precipitation increases to the peripheral foothills and low-mountain areas. Its low annual values are characteristic for the valley and delta of the Selenga. Increased R30 values are observed in foothill and lowland areas, and on the slopes of ridges, open to moisture-bearing air masses, they are high. These are the western and northeastern slopes of the Eastern Sayan, the southern slopes of the Tunkinskiye Goltsy ridge, the north-western slopes of the Ikatskii and Yablonevskii range, the northern ones of the Khamar-Daban ridge, etc. The erosion index of precipitation at the same point of observation varies considerably in time, in different years it can vary many times (Bazhenova et al. 1997). The analysis of the long-term dynamics of R30 allows us to speak about the rhythms of soil erosion caused by the cyclic course of rainfall (Fig. 30.5).

482

O. I. Bazhenova et al.

Fig. 30.4 The distribution of mean annual values of the erosion index of precipitation (R30) in the territory of the south of Eastern Siberia (Bazhenova et al. 1997). 1. less 2; 2. 2.1–3.0; 3. 3.1–4.0; 4. 4.1–5.0; 5. 5.1–6.0; 6. 6.1–8.0; 7. 8.1–10.0; 8. more 10

Fig. 30.5 Long-term dynamics of erosion index of precipitation in Irkutsk (Bazhenova et al. 2016) (The dashed line is annual data, and the solid line is smoothed over three-year periods)

Thus, throughout the investigated area the rainfall is a serious threat of erosion processes. The quantitative assessment of the erosion hazard of rains by the erosion index of precipitation allows predicting the probable annual washout values for areas with moderate, medium, high and very high rainfall hazard.

30.4.2 Anti-Erosion Stability of Soils The intensity of erosion processes is largely determined by the features of the soil cover. The anti-erosion stability of soils depends on many quantities, primarily on the mechanical composition and humus reserves. The washout soil stability increases with increasing content of silty particles and decreases with increasing content of dusty fractions and very fine sand (Larionov 1984). The index of soil washout stability is the coefficient of soil erosion (t/ha) per unit of precipitation erosion index.

Let’s consider the anti-erosion resistance of soils on the main agricultural enclaves. A nomogram was used to calculate soil erosibility (Larionov 1984). Its most important parameters are the humus content and granulometric composition: the percentage of sand (0.1–1.0 mm), as well as the total content of dust and fine sand (0.1–0.001 mm). These indicators cause both the soil resistance to erosion by slope runoff, the structure’s ability to withstand the destructive effect of rain drops, and the water permeability, determined by the amount of surface runoff. The coefficient of soil erosibility (Kc) in the south of Eastern Siberia varies from 0.8 to 4.5 t/ha. The most washout resistant soils were leached chernozems (Kc 0.8–1.4 t/ha) and ordinary chernozem (Kc 1.0–1.4 t/ha), and dark gray forest soils (Kc 0.9–1.6 t/ha). Chestnut soils are more prone to erosion (KChestnut soils are more 2.7–3.4 t/ha), sod forest (Kc 2.3–4.5 t/ha), sod-podzolic (Kc 2.5–2.9 t/ha), sod-carbonate (Kc 1.6–2.9 t/ha) and light gray forest (Kc 2.3– 3.9 t/ha). The soils of the Nazarovskaya,

30

Soil Erosion on the Agricultural Lands of the…

483

Yuzhno-Minusinskaya and Kanskaya depressions are characterized by high erosion resistance. Less resistant to washout are the soils in Tuva, Tunkinskaya and Barguzinskaya depressions.

30.4.3 Erosion Potential of the Relief This indicator reflects the influence of the slope geometry on the formation of the runoff, its concentration, and eroding and transport capacity of slope water streams. Usually, the erosion potential of the relief is estimated according to two most important parameters-the length and steepness of the slopes (Larionov 1984; Mitchell and Bubenzer 1984): the longer and steeper the slopes are, the higher the erosional potential of the relief (EPR) is. Therefore the southern regions of Eastern Siberia are characterized by a complex strongly dissected relief; they should be referred to the zone of slope agriculture with high EPR values. Large foci of farming are associated with intermountain and inland mountain depressions, foothill denudation plains. Here not only gentle slopes are plowed, but often surfaces with a steepness of 9–12°. The computation of the EPR is a very labor-intensive stage of the study, including a detailed morphometric analysis of large-scale topographic maps. Based on the processing of topographic maps of scale 1∶100,000, we constructed maps of slope steepness and the density of horizontal dismemberment, as well as calculated the EPR and compiled the maps for the main agricultural regions of Eastern Siberia (Bazhenova et al. 1997). The EPR varies from 0.1 to 20. As an example, we consider the distribution of the EPR of the Kanskaya depression (Fig. 30.6). A wide variety of surfaces of different length and steepness caused a lot of combinations of slopes with different EPR. It should be noted that in general the relief of the Kanskaya depression is characterized by a low erosion hazard. On 67% of the territory the ESR does not exceed 4 (together with the foothills). Moreover, 10.5% of the whole territory considering the relief refers to erosion-free lands namely the bottoms of valleys, lake basins, zone of deluvium accumulation and biogenic accumulation (bog), their EPR values equal to zero. The lowest values of EPR (0.1–2) are characteristic for flat and gradual types of relief, associated with the shallow basins, made by Jurassic sediments. The erosion potential of the hilly-steep relief type, which varies within the limits of 4.1–10 and which is characteristic of the foothill areas, considerably increases. A very high erosion potential (more than 10) is characteristic for the deep dismembered relief of the foothills of the Eastern Sayan and the South Yenisei ridge. Thus, there is an increase in the EPR from the central regions of the depression to the

Fig. 30.6 Erosion potential of the relief of the Kansk basin (Bazhenova et al. 1997). 1. Erosionally non-hazardous surfaces; EPR: 2. 0.1–2.0; 3. 2.1–4.0; 4. 4.1–6.0; 5. 6.1–8.0; 6. 8.1–10; 7. 10.1–14; 8. 14.1–18; 9. 18.1–20

periphery. The most unfavorable is the relief of the western and southern regions. The average value of the relief factor of the Irkutsk– Cheremkhovo plain is 2.29 (Litvin 2002). According to the morphological appearance, four types of erosion-denudation relief are distinguished here. The hilly and steep relief is widespread in the northwestern and southeastern parts of the plain, as well as along the right bank of the Angara river. The hollow-wavy and flattened relief is associated with the central parts of the plain. The EPR increases from the central sections of the Irkutsk–Cheremkhovo plain to the southwest towards the foothills of the Eastern Sayan and to the northeast to the valley of the Angara. A complex spatial distribution and high EPR values are characteristic for the Nazarovskaya and Yuzhno–Minusinskaya depressions (Bazhenova et al. 1997). In general, there is a gradual increase in EPR from the bottom of the depression to the spurs of mountain ranges. The same

484

character of EPR distribution is inherent in the depressions of Tuva. In the depressions of the Baikal rift system (Barguzinskaya, Tunkinskaya, Mondinskaya, and others), a sharp increase in the EPR values from accumulative bottoms to the mountain frame is observed.

30.4.4 Soil Protection Properties of Agrocenoses The washout intensity from arable lands and the possibility of its occurrence depend to a large extent on the soil protection properties of vegetation, as well as on the cultivation type. The average values of the erosion index of agrocenoses in the runoff of rainwater are higher (C = 0.41 – 0.50) in the western part of the territory (south of the Krasnoyarsk Territory, Tuva, and the Irkutsk region) than in the eastern (Buryatia and Transbaikalia), where it is 0.31–0.40 (Zharkova 1987). The erosion index of agrocenoses varies in time, depending on the change in the structure of agrocenoses. At present, due to the conservation of agricultural land, the soil protection properties of vegetation in the south of Siberia are increasing. A typical example of such a transformation is the Kuda river basin, located in the Lena—Angara forest-steppe. Figure 30.7a, b presents the results of studying the dynamics of agrocenoses using the interpretation of Landsat 7 and 8 satellite images as of 1989 and 2016 (Tukhta 2017).

Fig. 30.7 Change in the structure of agrocenoses in the basin of the Kuda river valley from 1989 (a) to 2016 (b) (Tukhta 2017). 1. Lea (0.70); 2. Cereals (0.31); 3. Fallow lands (0.05); 4. Meadows (0.05); 5. Vegetable gardens (0.65); 6. Forest (0.05); 7. Felling (0.7); 8. Burnt forests (0.7). (The values of the erosion index of agrocenoses are given in parentheses)

O. I. Bazhenova et al.

30.4.5 Erosion-Hazardous Lands in the South of Eastern Siberia The analysis of the main factors of slope washout has shown that the numerical expression of the parameters on this territory varies considerably. Table 30.3 presents the distribution of zones with different intensity of potential washout for the main agricultural enclaves of the south of Eastern Siberia. In the Nazarovskaya depression, according to the detailed calculations, 8 zones with different washout intensity were identified (Fig. 30.8). It is established that erosion-free lands occupy 18% of the depression. These include the bottoms of valleys and lake basins, deluvial and proluvial trails. Washout is also absent in areas without a cover of loose material, occupying about 2% of the territory. Rock outcrops are common on the Solgonsky ridge and Arga range in the areas of low-mountain relief. With longitudinal plowing of gently slopes less than 3°, occupying 9% of the territory, a weak washout will be carried out. On all surfaces, with the erosion potential less than 2, the washout intensity will not exceed 4 t/(ha a), regardless of the value of the remaining parameters. A washout of medium intensity is possible in 19% of the area. Plots with a washout of 4–8 t/(ha a) are particularly widespread in the northern half of the depression, where the EPR is low (no more than 4) and leached chernozems are widespread. In addition, large plots of land

30

Soil Erosion on the Agricultural Lands of the…

Table 30.3 Distribution of zones with different intensity of potential soil washout in the main agricultural areas of the south of Eastern Siberia

485

Washout intensity/[t/(ha a)]

Nazarovskaya depression

Kanskaya depression

Yuzhno– Minusinskaya depression

Irkutsk– Cheremk hovo plain

Tunka depression

2

27

52

34

19

30

2–5

14

23

27

21

25

5–10

28

17

12

45

25

>10

31

8

27

15

20

the washout rate can increase to 24–32 t/ha and will characterize the washout as very strong or catastrophic. And, finally, in 17% of the area the rate of potential washout will be more than 32 t/(ha a). In general, there is an increase in the washout intensity from the bottom of the depression to the periphery (Fig. 30.8). The agricultural lands of the Kanskaya depression are divided into four categories according to the degree of erosion hazard (Fig. 30.9). In general, the Kanskaya depression

Fig. 30.8 Erosion-hazardous lands of the Nazarovo depression (Bazhenova et al. 1997). 1. Weak erosion hazard (washout less than 4 t/ha); 2. Mean erosion hazard (4.1–8.0 t/ha); 3–5. High erosion hazard (3. 8.1–16.0; 4. 16.1–32.0; 5. more than 32 t/ha)

with an average intensity of potential washout are located to the north of the valley of the Beresh river, east of Lake Beloye, as well as in the south of the depression. In all these areas with a significant EPR the low washout intensity is caused by a low erosion index of precipitation. The remaining area (56%) is subject to strong washout (more than 8 t/ha a). The zone with the washout intensity of 8–12 t/ha takes 12%. It is located mainly in the central part of the depression to the north of Lake Beloye and the valley of the Serezh river, as well as to the north-east of the village Sakhapta. In the north of the depression within the zone adjacent to a wide long strip from the south to the valley of the Chulym river, a washout with the intensity of 12–16 t/ha is possible. The same washout is possible in the southern part of the Ashpan range, in the areas of shallow and hilly-ridge relief, only on 7% of the area. A strong washout with an intensity of 16–24 t/(ha a) can be observed in 10% of the area mainly in the south-west of the depression at the sites of a combination of low erosion index of precipitation (2) with high erosion potential (20) of shallow and hilly ridge relief types. To the northeast of this zone, with the increase in the erosion index of precipitation,

Fig. 30.9 Erosion-hazardous lands of the Kanskaya depression (Bazhenova et al. 1997). 1. Non-hazardous [washout less than 2.5 t/ (ha a)]; 2. Weak erosion hazard [2.5–5 t/(ha a)]; 3. Mean erosion hazard [5.1–10 t/(ha a)]; 4. High erosion hazard under the forests [potential washout more than 10 t/(ha a)]

486

is characterized by a moderate development of soil erosion processes. In accordance with the change in the main erosion factors on the agricultural lands of Khakassia (Yuzhno-Minusinskaya depression) Artemenok (1998) also identified four zones with different erosion hazards. However, she classified 33.6% of the agricultural area of the republic as erosion-free. Weakly erosion-prone lands occupy 26.8% of the area, medium erosion-hazardous lands are spread over 12% of the area, and 27.6% of the potential annual washout area reach more than 10 t/ha. In general, the agricultural lands of Khakassia are characterized by average values of potential storm shower washout. The erosion danger increases from the central regions of the depression to the periphery. In the Tunkinskaya depression, the potential washout calculations for four farms (Ryzhov 2015) showed that 55% of the area does not exceed 5 t/(ha a). This includes mainly areas on the surface of the Irkut river terraces and the central part of the basin with inclines of less than 1°. A significant part of such lands is erosion-free. More than a quarter of all arable lands located on gentle slopes with a steepness of 1°– 3°, associated with the lower parts of the foothills of the Khamar-Daban ridge and Tunkinskiye Goltsy, can lose 5–10 t/ha of soil annually. 2875 hectares have a potential washout of 10–20 t/(ha a). These are areas with an average steepness of 2°–7°. Only on 5% of arable lands does the potential washout exceed 20 t/(ha a). It is associated with the slopes of the Elovskii spur and the Khamar-Daban ridge with an average gradient of 3°–6°. Four zones were identified in the Irkutsk–Cheremkhovo plain according to the degree of erosion hazard of lands (Bazhenova et al. 1997): I-very weak washout (average annual losses less than 2 t/ha), II-weak (2–5 t/ha), III-medium (5–8 t/ha), IV-strong washout (more than 8 t/ha). The zones with a high potential washout are associated with the Angarskaya heavily dissected strip of the plain, to the sag and swell relief within the plain and to the foothills of the Eastern Sayan. Figure 30.10 presents the distribution of erosion-hazardous lands in the eastern part of the plain, which belongs to the basin of the Kuda river. We will especially mention the processes of soil degradation in the Baikal watershed basin, as the degree of soil erosion as one of the main criteria for assessing the ecological situation in any region. It occupies a leading position not only among the regions of southern Siberia, but even among the 67 administrative entities of the Russian Federation belonging to the agricultural zone of Russia. Buryatia is on the third place (Namzhilova and Tulokhonov 2000). According to the latest correction of total erosion of agricultural land in 9 districts of Buryatia, this figure exceeds 50%, which allows them to be classified as in an emergency environmental situation.

O. I. Bazhenova et al.

Fig. 30.10 Erosion-hazardous lands of the Kuda river basin (Tukhta 2017). 1. Non-hazardous (washout less than 1 t/ha); 2. Weak erosion hazard (1–2.5 t/ha); 3. Moderate erosion hazard (2.5–5 t/ha); 4. Mean erosion hazard (5–10 t/ha); 5. High erosion hazard (10–20 t/ha); 6. Extremely hazardous (washout more than 20 t/ha)

The maps-schemes (Fig. 30.11) represent the spatial distribution of these processes in the agricultural areas of the Lake Baikal basin; they show zones with different intensity of erosion and aeolian processes (Bazhenova 2009). When identifying the zones, the materials of the soil-erosion survey of Vost Sib Gyprozem, the published data on distribution and intensity of the processes, and the results of a quantitative assessment of the main erosion factors obtained by calculation were used as the initial information. Mapping was preceded by the stage of converting the initial indicators of land degradation, expressed in hectares, to the form of washout and deflation indexes, reflecting on the 100-point scale the territory’s damage by one or another process: IeðdÞ ¼ 100SeðdÞ =S

where, Ie(d) is the erosion or deflation index; Se(d) is the affected area, ha; S is the total area, ha. The larger the washout or deflation index is, the greater the area of foci and the massifs of land destruction in a given territory are. The selected methodical method ensured the comparability and objectivity of assessments of the land

30

Soil Erosion on the Agricultural Lands of the…

Fig. 30.11 The zones of contemporary occurrence of the processes of erosion loss (a), gully erosion (b) and deflation (c) in agricultural areas of the Lake Baikal watershed basin (Bazhenova 2009). Intensity of

Table 30.4 Quantitative parameters of intensity of development of erosion and Aeolian processes in the agricultural areas of the Lake Baikal basin

487

processes: 1. Weak; 2. Moderate; 3. Strong; 4. Watershed territories whose soils are not experiencing anthropogenically accelerated loss, scouring or deflation (For the symbols, see Table 30.4)

Parameter

Processes intensity Weak

Mean

High

Deflation index

50

Anti-deflation stability of soils/%

50–70

30–50

10–30

Deflation

Slope washout Washout Index

50

Coefficient of soil erosibility

0.7–1.5

1.5–2.5

>2.5

50

0.50

Gully erosion Density of gullies/(units/100 km2) 2

The density of the gullies network/ (km/km )

erosion of different categories by the nature and degradation degree. The soil sensitivity to erosion processes was also assessed using design coefficients that depend on their physicochemical properties (particle size distribution, humus content, Ca and Mg cations, water permeability, connectivity, etc.) and determine the stability or compliance of soils to washout, erosion and deflation. The quantitative values of the parameters used to estimate the intensity of erosion and aeolian processes are shown in Table 30.4. By the end of the 1980s the area of eroded lands in the Lake Baikal basin exceeded 1 million ha (Namzhilova and Tulokhonov 2000). Here there are more than 9.5 thousand gullies, they occupied 12 thousand hectares of land, and the total length of the gully network is 8665 km (Tarmaev 1992). More than 50% of the gullies are intensively growing. The gully network is especially dense in the Dzhida river basin, on the interfluve of the Selenga and Chikoi rivers (Kyakhta district), in the Selenga and Tarbagatai districts. The plowing of sandy and sandy loamy soils at the stage of opening up of virgin lands transformed them into masses

of shifting sands with the area of more than 100 thousand ha (Ivanov 1966). The load on pastures exceeded the maximum permissible level for many years; the sheep population in the mid-1970s reached 2 million. Therefore, pastures, primarily used for grazing sheep, are characterized by congestion and degraded vegetation. Disturbance of the thick protective layer of steppe felt kaldana, as a result of overgrazing, contributed to the increased erosion risk of pastures. In the early 1990s in the agriculture of Buryatia serious changes related to the reform of the entire national economy of the country occur. Khanduev (1996) presents the result of the reduction of financial, material and labor resources, the bases of the republic’s agriculture were undermined. At the same time, there was an abrupt reduction of arable land from 877,000 ha in 1975 to 550,000 ha in 1995, that is, by almost 40%. It should be especially noted that the number of sheep giving the greatest burden on pastures during this period has decreased from 1950 thousand heads to 455, i.e. more than fourfold. The process of arable land conservation spontaneously continues now, approximately at a rate of 1% per

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year. Over the past 9 years, the area of arable land in the Kyakhtinskii district has decreased by another 4532 ha (7%), in the Mukhorshibirskii-8474 ha (8%), in the Dzhidinskiy-3230 ha (9%), and in the Zaigraevskii-3375 ha (9%).

30.5

Trends in Erosion Processes

The analysis of long-term variability and directivity of erosion processes was based on information on the runoff of suspended sediments in 18 basins (Table 30.5). We revealed a rather complex long-term behavior of erosion processes with well-defined cyclicity. The sediment discharge modules (see Table 30.5), provided with long series of observations (more than 20 years), show a weakening of erosion from the forest steppes to the steppes and in general from west to east, i.e. from the Ob river basin (the Chulym river) to the Baikal and Amur basin (Southeast Transbaikalia). Table 30.5 Runoff of the suspended sediments on Southern Siberia

River-point

Chulym–Balakhta village

The forest-steppe regions are also characterized by a larger value of the linear trend of sediment discharge. Within the basin of the Ob river, they are positive and indicate an increase of the role of erosion processes in soil degradation. In the southeastern part of the Baikal region (the Angara basin) and in Western Transbaikalia, a downward trend of erosion is noted. In the Onon-Argun steppe (the Onon river basin), a slight increase in the intensity of the processes is observed, due to an increase in atmospheric moisture. The Shusha river basin (the Minusinsk steppe region) is distinguished by well-marked positive trend of the sediment runoff module; however, in most of the Yuzhno-Minusinskaya depression, the intensity of erosion processes is weakened. This is typical, first of all, for areas with a high positive trend of air temperature. One of the possible causes of the downward trend of the sediment runoff module is a decrease in the climate continentality over the last 30 years, and hence the unevenness of the water runoff.

Catchment area/km2

Number of years of observations

Sediment runoff module/[t/(km2 a)] Mean

Min

Max

Trend

14,700

29

26.0

9.2

114.4

0.61

531

28

46.3

8.3

142.2

1.18

Abakan–Abaza settlement

14,400

35

23.7

5.1

92.4

–0.42

Shush–Idzha village

Yenisey–Kyzyl

115,000

36

11.0

4.1

23.2

–0.05

Kan–Irbeiskoye village

8710

39

11.0

4.0

34.6

0.04

Birysa–Shitkino village

24,700

40

10.2

2.5

20.8

0.07

3840

29

6.6

3.1

21.3

–0.13

14,500

38

16.1

2.2

50.6

0.46

4980

27

11.5

0.9

63.0

0.35

Vikhoreva– Koblyakovo village Iya–Tulun Uda–Alygdzher village Ikey–Ikey village

2400

23

59

1.3

21.0

0.26

Irkut–Smolenshina village

14,800

38

34.3

3.2

75.3

–0.99

Olha–Olha village

590

40

2.7

0.6

13.4

0

Chikoy–Gremyachka village

15,600

36

9.5

2.2

34.0

–0.07

Khilok–Hailastui village

38,300

38

3.3

0.5

9.5

–0.01

Uda–Ulan-Ude

34,700

39

2.8

0.5

7.5

–0.06

Selenga–Mostovoy

440,000

44

4.6

0.8

85.2

–0.06

Barguzin–Barguzin village

19,800

46

7.5

1.8

35.2

–0.10

Onon–Bitev village

49,500

24

8.5

1.4

22.5

0.02

30

Soil Erosion on the Agricultural Lands of the…

Table 30.6 Change in erosion hazard of cloudburst in steppe and forest-steppe of Siberia

Point

489 Number of years of observations

Erosion index of precipitation Mean

Min

Max

Trend

Achinsk

30

5.9

0.1

39.4

0.10

Krasnoyarsk

31

6.1

0.1

25.3

0.08

Uzhur

21

3.8

0.2

16.0

0.30

Shira

28

4.9

1.0

24.9

–0.19

Khakasskaya

31

6.5

0.7

42.5

–0.12

Beya

28

5.1

1.0

19.0

0.13

Kyzyl

26

2.1

0

8.5

0.12

Zima

33

3.0

0

13.6

0.03

Balagansk

28

2.5

0

6.7

–0.07

Bayanday

33

4.4

0

14.5

–0.07

Cheremkhovo

26

3.7

0

16.1

–0.08

Khomutovo

26

4.1

0.2

12.4

–0.01

Irkutsk

53

7.1

0.2

23.6

–0.16

Sarma

27

1.6

0

Ulan-Ude

23

3.5

0.5

11.0

–0.05

Barguzin

25

4.1

0.4

14.3

–0.12

Since the main role in the formation of water runoff on the slopes and the washout of soils in this area belongs to torrential rains, we researched a long-term course of the erosion index of rainfall determining for a 30-min rain intensity according to the data of 17 weather stations (Table 30.6). The obtained linear regional trends almost everywhere coincide with the trends of sediment runoff, which increases the reliability of the obtained trends in the erosion processes occurring against the background of climate fluctuations. In the Ob basin there is an increase in the erosive danger of showers, mostly significant in the Nazarovskii forest-steppe region (Uzhur). To the east, in the Krasnoyarsko-Kanskii region, the increase rate of this index is gradually decreasing, and in the Baikal region the trend sign changes from positive to negative, as well as by the trend of sediment discharge, which indicates a decrease in the intensity of erosion processes. A particularly rapid drop in the erosive danger of showers is noted according to a 53-year series of observations at the Irkutsk weather station, the index in the Barguzinskii district is decreasing at the same rate. In the Barguzinskaya depression the data by Ryzhov (2015) show the decrease in the growth rate of small erosional forms of relief. The negative trend of rainfall is typical for Western Transbaikalia, Priol’khonye and steppes of Khakassia. In the Koibal’skii foothill-steppe and Kyzyl desert-steppe regions, the erosion index of precipitation increases approximately at the same rate (see Table 30.6).

5.12

–0.03

Based on the statistical analysis of long-term observation series of the suspended sediments runoff, the basins are identified, which are merged in four regions with different trends in the behavior of erosion processes. The prevailing trend in the first Ob-Yenisei region with a positive trend of atmospheric humidification is an increase in the intensity of erosion processes. It is characteristic for 80% of the basins in the region. In the structure of erosion processes, the role of flash shower increases, as indicated by the positive trends in the erosion index of precipitation. The second Angara region is characterized by a complex multidirectional nature of the process intensity change. Against the background of the generally downward trend of erosion processes caused by the negative trend of atmospheric humidification and the decrease in water reserves in snow, in some river basins there is a noticeable activation of erosion activity associated with massive felling of forests. The strongest influence of concentrated felling on erosion processes is manifested in felling not older than 2–5 years. If the deforestation occupies 1–5% of the basin area, the suspended sediment runoff module increases by 50–300%, the turbidity of the water increases it by 100–800% (Burenina and Onuchin 1999). Currently, the volume of wood harvesting in some areas is increasing. The activation of erosion processes is also associated with an increase in the number of fires. The area of new fires in separate basins is twice the area of fresh felling. The strongest increase in the intensity of erosion processes is noted in the influence zone of the Bratsk reservoir, i.e. in the basins of

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the rivers Unga, Osa, Zalari, Oka, Belaya and other tributaries of the Angara. The average growth rate of small erosion forms in loess-like loams is 0.2–2.0 m/a. In the third Selenga district, covering the basins of Barguzin and Selenga rivers, the descending trend of suspended sediments runoff predominates. The main reason is an abrupt decline in agricultural activities in this area over the past 20– 25 years. In some areas of Buryatia, where practically complete closure of agriculture due to socio-economic reasons is noted, the growth rate of gullies, the rate of flat erosion on slopes and the extent of sediment runoff are decreasing (Bazhenova and Kobylkin 2013). For the fourth region (the Upper Amur basin), the opposite tendency is characteristic: an increase in the intensity of erosion processes against the background of the progressive growth of atmospheric humidification in the second half of the twentieth century. Directed increase in sediment runoff in Transbaikalia in 1970s–1980s was noted by Bobrovitskaya (1995). A sharp increase in the intensity of gully erosion in the south of Transbaikalia at the end of the twentieth century was caused, in the opinion of Golosov (2006), by increased monsoon rains. During the years 1989– 1991 the annual layer of precipitation, which fell in the upper reaches of the Onon river increased by 50% in comparison with the average annual norm and exceeded 600 mm. This was due to falling out by a layer >40 mm in the summer months, which had not previously been observed within the region. Rapid development of gully erosion in a number of plowland plots led to a sharp increase in the number of gullies and the formation of 17 badlands. At the same time, the growth rates of gullies were dozens, and sometimes hundreds of meters per year (Golosov et al. 1996). Thus, the revealed positive trends of erosion processes are characteristic for the basins with high process intensity (the Yenisei and Amur basins). Due to the climate change, these trends will become even stronger. The most significant increase in sediment runoff should also be expected in areas of new economic development (development of gold, oil, gas, deforestation, etc.). In this regard, in order to reduce the amount of runoff and improve the ecological situation, we need measures of environmental and geomorphological safety, primarily restoration and creation of new anti-erosion protection systems.

30.6

(Western Siberia) and storm waters (south of Eastern Siberia, and Transbaikalia), high relief energy: convex (more than and long slopes (200–1000 m), deep vertical relief, loesslike sandy loam and loam. Gully systems are concentrated mainly on the slopes of interfluves and river valleys; they consist of bottom and slope gullies, patches and erosion furrows. At an average insignificant (0.01–0.05 km/km2) length of gullies along the territory of the forest-steppe zone in places of local development of gully systems, their length reaches 1.6–2.7 km/km2 (Putilin 2002). In Western Siberia, the areas affected by gullies occur along the left high bank of the Ob river (Priobskoe plateau), on the Cherepanovskaya plain, Kolyvan-Tomskaya and Biye-Chumyshskaya uplands (Fig. 30.12), and on the Prisalairskaya inclined elevated plain. Sometimes gullies stretch for tens of kilometers. Their depth usually does not exceed 30 m, and the length 1 km. The slopes of the gullies are steep enough (up to 30°–40°). The average annual increase in the peaks of gullies is from 3 to 8 m, the bulk of which falls in the spring. On the plains and plateaus of the south of Eastern Siberia, gully erosion tends toward river valleys, bottoms and slopes of large beams, and falls (Fig. 30.13). In the intermountain and intermontane basins the erosion forms are associated with the treeless slopes of the foothill plains with erosion-denudation, erosion-accumulative relief. In the Minusinskaya depression linear furrows are most typical, which are associated with the lines of plowing in natural depressions of the relief, for example, to the thalweg of beams. They are shallow, narrow, canyon-like, with a length of 200–500 m. Their age is one to three months. When agricultural fields are treated in spring or autumn, erosion forms are equalized. The plowed up upper slopes on the

Gully Erosion

The gullies on the agricultural lands of the south of Siberia have a local distribution. They are concentrated in the forest-steppe and steppe landscapes and have been formed during the last 100–200 years. The development of gully erosion is facilitated by large amounts of runoff from melt

Fig. 30.12 Gullies on the agricultural lands of the Priobskoe plateau in the southeast of Western Siberia (based on Google Earth, filming 4 June 2014)

30

Soil Erosion on the Agricultural Lands of the…

491

contact of the forest (steppe) and the arable land have the deepest density of linear forms and are most profoundly eroded. Large gullies and gullies, impassable for agricultural machinery, are single on arable land. They, as a rule, are plowed around. In the Angara region the main areas of erosion forms are located in the forest-steppe agricultural areas of the Irkutsko–Cheremkhovskaya plain and the Leno– Angarskoye plateau. The maximum density of gullies (more than 50 units/100 km2) is noted in the valleys of the rivers Osa, Unga, and Ida, along the shores of the Bratsk reservoir in the area of loess loamy, Cambrian siltstones and marls. A large number of erosion forms per unit (25–50 units/100 km2) was recorded in the upper reaches of the Zalari, and Unga rivers, the left bank of the Belaya river, between the rivers Oka and Iya, on the ledges of the high rock-defended terraces of the Lena river near the town of Kachug. For the Angara region, the density of erosion forms of 10–25 units/100 km2 is typical (Ryzhov 2015). In Transbaikalia gullies are widespread in areas with a high degree of economic development, i.e. the valleys of Selenga, Uda, Khilok, Chikoy, Djida, Onon, and Argun. Their density reaches 50 units/100 km2 and more, for example, the density of gullies on the Kuitunka river catchment area (in the Selenga middle mountains) in powerful loess-like sandy loam is 390 units/km2. In the forest-steppe gullies reach the maximum sizes (in loess-like sediments their length is up to 4–6 km, depth is up to 20–30 m, in sandy sediments up to 1 km, the depth does not exceed 3–5 m). The arable lands are actively eroded on the slopes of low mountain ranges in the steppe of South-Eastern Transbaikalia. Here there are local and areal linear forms, which are associated with natural and artificial (arable furrows, road network, etc.) runoff lines. Watercourses from the fields

are formed when precipitation falls with a sum of just over 5 mm and an intensity of 0.02–0.03 mm/min. The storm streams during rains with a precipitation sum of 10–20 mm and an intensity of 0.10–0.50 mm/min in places of natural depressions break through the furrows and rush down the slopes. Local jet erosions and gullies appear with a stepped longitudinal profile. Particularly erosive are showers with a precipitation amount of more than 50 mm and an intensity of more than 1.0–1.5 mm/min, when the fields are covered by a network of linear forms. For example, after showers of July 10–13, 1979, with a precipitation amount of 54 mm and a maximum intensity of 1.8 mm/min on the plowed slope of 3°-5°northwest of the village Kharanor, the density of local erosion with a length of 150–200 m, depth of 30 cm was 10 units/km2. Moreover, the entire surface of the arable land was subject to general flat washout and small-jet erosion. In some areas, the upper soil horizon was demolished together with sowing, the height of wheat germs reached 20 cm. On average, the removal of fine earth from the field amounted to 240 m3/ha. In the basin of the Kunaleika river (Western Transbaikalia), after storm rains in the summer of 1988, 42 new gullies with a length of 12 km were formed, 37 thousand tons of small-product soils were redeposited, 28 hectares of arable land were removed from use (Tarmaev 1992). The results of long-term studies of gully erosion in southern Siberia indicate a very uneven development of erosion forms in time. For linear forms of erosion, a rapid initial stage of development is typical, associated with the precipitation of heavy showers and prolonged rains. Plots of arable lands and especially the fallow lands on slopes with steepness of 3°–10° when rain falls, heavy rains, and during a turbulent snowmelt, are subject to strong and very strong erosion. In the usual moderately humid years, the rate of

Fig. 30.13 Zoning map of southern East Siberia by gullies density. 1. Very rare distribution of gullies (0.003–0.006 km/km2; 0.011–0.020 units/km2); 2. Sporadic distribution of gullies (0.006–0.030 km/km2; 0.021–0.100 units/km2); 3. Weak distribution of gullies (0.031–

0.100 km/km2; 0.101–0.250 units/km2); 4. Medium distribution of gullies (0.101–0.200 km/km2; 0.251–0.500 units/km2); 5. High density of gullies (>0.201 km/km2; >0.501 units/km2) (according to Ryzhov 2015); 6. Gullies are absent or rare ( 10 km2. (2) Water balance Tailings with a very high proportion of fine to medium-sized pores have limited possibility for gravitational drainage and the tailings remain largely water saturated. Precipitation directly onto tailings will lead to infiltration and eventually to seepage of water from the tailings dam wall and at the interface of natural drainage points on an otherwise very low permeable underlying geology. Arid and semi-arid environments allow drying from the top, but the depth of water extraction by evaporation remains very shallow and may not substantially deplete pore water from below 2 m depth (Baumgartl and Richards 2012). Tailings with a higher proportion of coarser particles, as can be found in earlier

The objective of restoration of tailings is to minimize risks of failure as are identified during the operational phase, but also to consider additional post closure risks of e.g. rainfall-erosion related processes of the structural elements of a TSF, overtopping of water following high amounts of rainfall and failure of the functionality of a protective cover or capping constructed on tailings. While there are tailings with a low chemical reactivity, most of the tailings produced are very reactive over long periods of times with potential negative impacts to the environment. To minimize any long-term impact of TSFs to the environment and treatment of the consequences in perpetuity (e.g. seepage; dust), de-coupling TSFs from the hydrological cycle is a commonly applied strategy. Constructing a cover on top of the TSF using local materials or encapsulating TSFs with e.g. geo- membranes are possible solutions to prevent water infiltration into the tailings and to separate tailings from natural hydrological processes. Tailings with coarser particle size distribution and chemically more or less benign tailings may be suitable for direct re-vegetation and successful attempts were made to re-plant woody species as tube stock or to re-seed grasses into tailings (Ni et al. 2014). Ageing processes may harden tailings mechanically so that they become less penetrable for plant roots over time. To improve accessibility of tailings for plant root growth, chemical and/or mechanical amendments may be required. Loosening of compact and unstructured tailings together with stabilization of the loosened material will improve root growth and water holding capacity. Chemical treatment may be required to improve substrate properties for plant growth. This may also foster the stimulation of microbial activity and trigger a positive feedback response to support the initiation of desired soil forming processes. Organic matter in various forms (compost; biochar; etc.) can be essential for successful restoration of otherwise low nutrient holding capacity substrate and may contribute to the acceleration of soil forming processes. However long-term beneficial and sustainable use of amendment application requires a good understanding of type and quantity of any applied carbon source to prevent unwanted consequences and failure of revegetation in the medium- and long-term. For the construction of a functional root zone, it is critical to restore physical structure and hydraulic functions across the whole root zone system (Huang et al. 2012).

530

H. B. So et al.

If tailings are not suitable for root zone development, construction of a cover is not only necessary to control water flow, but also serves as a root growth medium and provides the basis for a large- scale landform design element of land restoration. The distribution, frequency and magnitude of rainfall events even at otherwise suitable climatic conditions may require more complex design solutions.

33.3

Case Studies

33.3.1 Restoration of Ecosystem After Bauxite Mining Bauxite mining in the dry sclerophyll eucalyptus forest of southwest Australia is a shallow surface mining operation. The current restoration goal is to restore the Jarrah forest values (Gardner and Bell 2007). One hundred percent of the species are now routinely returned (Fig. 33.8). Nutrient cycling appears to be on a trajectory towards restoring the nutrient stores and the fluxes of nutrients present in the pre-mining Jarrah forest (Grant et al. 2007). Hydrological balance is disturbed for up to 12 years after land clearing for bauxite mining and subsequent revegetation (Croton and Reed 2007). Thereafter, groundwater levels return to pre-mining levels, and may drop below pre-mining levels due to the increase in leaf area index relative to pre-mining levels (Bari and Ruprecht, 2003). The restored forest is resilient to fire (Grant et al. 2007). Completion criteria have been developed for bauxite mine restoration and several areas have been determined to meet the designated targets (Gardner and Bell, 2007). The present restoration practice as described by Koch (2007) is the result of four major revisions in the goals over 40 years and several other significant improvements in practice. The first rehabilitation simply planted Pinus radiata

Fig. 33.8 Bauxite mine rehabilitation in foreground; jarrah forest in background

as a single species plantation. This was followed by a Eucalyptus saligna plantation and then by a goal to restore a diverse forest rather than a plantation. At that time, it was thought that planting of local eucalyptus would not succeed because of the existence of Phytophthora cinnamomi in the soils and its threat to the survival of a wide range of native species. Further research demonstrated that the reconstructed profile produces a low risk of P. cinnamomic infection in susceptible species, and hence, it was decided to change the end land use goal to that of a forest compatible with the Jarrah forest, using jarrah ( Eucalyptus m arginata) and marri ( Cor ym bia calophylla) as the over story species (Gardner and Bell 2007). Finally, it was decided to revise the end land use goal to achieve the restoration of the Jarrah forest (Fig. 33.8) (Grant et al. 2007). The selection of this goal was based on research breakthroughs that demonstrated that it was possible to stimulate the germination and emergence of recalcitrant species and hence reach close to 100% species return. The main learning from this case study is that achieving practices that enable full ecosystem restoration takes several cycles of research and adaptive management. It is based on a systematic program of research into biotic and abiotic constraints. A flexible approach from regulators enabled end land use goals to be revised over time as new research demonstrated the potential to achieve more challenging goals and targets. The end land use goals set in 1963 would have only resulted in exotic pine plantation on the mined bauxite pits. The present end land use goal is now a fully functioning Jarrah forest that can be integrated into existing forest management programs and achieve the multiple land use goals for the forest estate (Gardner and Bell 2007).

33.3.2 Designing Postmining Landscapes Following Open-Cut Coalmining that Minimise Erosion Risk and Discharges on the Receiving Environment While underground mining has relatively small footprints, open-cut mines such as coal disturb large areas of the land surface. In open-cut mining, the deep overburden above the coal seam is blasted using explosives and then removed mechanically using trucks and shovels or draglines. The latter is the most common method used in Central Queensland coal mines resulting in landscapes that consist of long (up to several 10s of km) parallel overburden spoil-piles that are generally saline, dispersive and highly erodible as shown in Fig. 33.9 (Williams 1996; Sheridan 2001). The height of these spoil-piles may exceed 50-60 m above the original

33

Issues and Challenges in the Rehabilitation and Sustainable Use of …

531

Fig. 33.9 On the left are a typical long parallel overburden spoil piles produced by dragline operation in a Central Queensland open cut coal mine (from Williams 1996) and a close-up view of the spoil-piles that can reach 50–60 m high (from Sheridan 2001)

landscapes and the slopes are at the angle of repose of around 75% or 37º (Carroll et al. 2004). In Central Queensland where most of these coal mines are located, the total area of land disturbed by open-cut coal mining and land already rehabilitated exceeds 146,000 and 44,000 hectares, respectively (Domagala and Wilson 2007). The current rate of land disturbance is estimated to be 5620 hectares a year, and the rate of rehabilitation is less than half the rate of disturbance, but expected to increase as new mines mature. Extensive open-cut coalmines are also found in the Hunter Valley of NSW, while brown coal is mined in the Latrobe Valley in Victoria. These new s urfaces are generally highly erosive, particularly where overburdens are saline and dispersive. In other cases, such as open-cut gold mining, the overburden consists of competent rocks and are stable against weathering and erosion. Legislation and public opinion require that these highly disturbed landscapes should be satisfactorily restored into an approved post-mining land use. The most expensive component of the restoration process is the re-shaping and landscape reconstruction which typically involves extensive and costly earthworks to produce a post-mining landscape that is resistant to geo-technical failure (land slip) and surface erosion processes by rainfall and runoff. As geotechnical failure tends to occur on very steep slopes, the discussion in this chapter is limited to erosion processes on the lesser slopes. Under current legislation, mines must apply for an Environmental Authority (EA) before mining operation can be conducted and a Financial Assurance (FA) may be required as part of the EA. The FA is a type of security provided to the Government, if a company fails to adequately rehabilitate the disturbed landscape. It is based on third party costing, since the government may have to employ contractors (third party) to conduct the restoration project should the mine fail to complete its obligation to rehabilitate the site (DEHP 2014, 2016). It is the responsibility of the company to develop an appropriate estimation of the FA based on the DEHP Financial Assurance

Calculator which has a detailed list of default unit costings for each step of the rehabilitation operation. In the case of high-risk overburden material (e.g. pyritic material that must be buried) the DEHP Financial Assurance Calculator estimates the default third party cost for reshaping and capping is $136,000 per ha (DEHP 2016). As soil and overburden materials exhibit a very wide range of erodibilities (Sheridan 2001), the extent and cost of earthworks can be minimized, and rehabilitation failures avoided, if soil erosion from designed landscapes can be predicted prior to construction. A methodology that assists mine-sites to efficiently and economically design post-mining landscapes ahead of reconstruction, and that will result in acceptable erosion rates (average annual erosion rates less than or equal to 12.5 t/(ha
a) or the natural erosion rates of the surrounding area) would be useful. As these landscapes are particularly vulnerable to erosion during the first few years following rehabilitation and prior to the establishment of adequate vegetation cover, this methodology should also allow the prediction of the probability of damaging erosion events from rainstorms as part of the risk assessment. Existing erosion models such as the Universal Soil Loss Equation (USLE) (Wischmeier and Smith 1960), and its revised version, RUSLE (Renard et al. 1991), and the Water Erosion Prediction Project- WEPP (Flanagan and Laflen 1997) were developed mainly for agricultural conditions where modifying land slope gradient is not an option, and where soils are cultivated and disturbed seasonally or annually. Therefore, soils are subjected to only limited seasonal consolidation (increase in bulk density and strength) between cultivation and are often cleared of rocks where they impede soil cultivation. Annual crops are sown onto cultivated land and crops progressively develop their canopy and root system reaching a maximum and then decline towards the end of the season. The erosion models generally require input data collected using field erosion plots conducted on the substrate of interest and the crops grown on them, which are resource intensive and time consuming. Soil

532

erodibility values used in these models refer to the property of the freshly cultivated soil, while the vegetation cover factor includes the effect of roots in consolidating the soil. In contrast, in the management of post-mining landscapes, changing slope gradients and slope lengths are the essential first steps necessary to stabilize the landscape. Overburdens are often high in rock content, while top-soils are often limited in quantity, of poor fertility and may consist of coarse-grained materials such as fine gravel. The topsoil applied to overburden is revegetated, then left undisturbed and allowed to consolidate (increase in bulk density and strength) with time. Vegetation cover fluctuates with season and may disappear temporarily due to bushfires which are a natural part of the Australian ecology. In the latter situation, the soil has been consolidated by the processes of wetting and drying and the presence of roots. Therefore, separating the effect of above ground vegetation and the consolidation of the soil including the effect of roots would allow the estimation of erosion rates from bare soils following bushfires. Existing agriculture-based erosion models were not intended to design new landscapes for erosion control on post-mining landscapes and a new approach was needed for that purpose. However, DEHP (Department of Environment and Heritage Planning) that is responsible for the supervision of mines and their restoration, requires the assessment of erosion control as mean annual erosion rates based on the RUSLE model. Here we describe a set of two user-friendly computer packages, the hillslope MINErosion 3.4 model and the landscape based MINErosion 4.1 model that were developed as tools to assist mine sites to design and achieve stable post-mining landscape reconstruction that will result in acceptable rates of erosion as the first major step towards the rehabilitation of these post-mining landscapes (So et al. 2011). These were linked to the RUSLE 2 and MUSLE models. MINErosion 3.4 is a predictive hillslope computer package that incorporates the RUSLE 2 and MUSLE equations, and is useful in the selection of suitable combinations of landscape design parameters (slope gradient, slope length and vegetation cover) for the particular soil/overburden of interest, that will result in acceptable rates of erosion. The slope length and slope gradient are parameters required by the mining companies as inputs into their landscape design software (e.g. Vulcan, Argus, Mincom etc) to cost- effectively construct suitable landscapes that will meet the required erosion criteria. MINErosion 3.4 accurately predicts both the annual average soil loss under the prevailing climatic conditions as well as the potential erosion from individual rainstorms with known annual recurrence intervals. A database of 35 soils and spoils from Central Queensland open-cut coal and gold mines, as well as consolidation and vegetative cover functions are imbedded in the model. These

H. B. So et al.

data were derived from laboratory rainfall simulator (RFS) experiments. The flowchart of the MINErosion 3.4 model is shown in Fig. 33.10. Three possible input options are shown in Fig. 33.10, with the main one being data derived from RFS experiments which is an efficient way of deriving the necessary input data. Where suitable RFS data are not available, routinely derived soil physical and chemical data can be used to estimate the inter-rill and rill erodibilities (Sheridan et al. 2000; Sheridan 2001). Alternatively, field rainfall simulator or field erosion plot data can be used as well to access the RUSLE 2 and MUSLE components of MINErosion 3.4. Figure 33.10 also shows that rainstorm event erosion rate for various recurrence interval can be derived using the MUSLE (Onstadt and Foster 1975). Figure 33.11 shows an example of the output as the mean annual erosion rates plotted against slope length for a 10% slope gradient, for nil (red) and 2 years of consolidation (black) and 20% vegetation cover of tussocky grass. A range of scenarios can readily be simulated. Similar output can be derived for rainstorm event erosion rates. When design parameters have been selected and suitable post-mining landscapes designed or constructed, MINErosion 4.1 can be used to estimate the rates of erosion from the designed landscapes. MINErosion 4.1 is a catchment/ landscape based predictive erosion package useful in the estimation of erosion rates (mean annual or individual rainstorm) from the proposed/reconstructed postmining landscape. It combines MINErosion 3.4 with Arc-GIS, where MINErosion 3.4 is applied to each raster which are defined by Arc-Gis. The outputs are maps of erosion and deposition on the landscape as well as discharges from the catchment/landscape units. This information will be useful in the management of the restored area, specifically for allocation of resources to the most vulnerable areas. For both models, the agreements with field data are very good (Khalifa 2010). An example of possible use and outputs from MINErosion 4.1 is shown in Fig. 33.12. It shows the result of simulation on a rehabilitated area at the Curragh minesite in Central Queensland after 10 years of consolidation and assuming a vegetation cover (stoloniferous grasses) of > 50% is achieved. The annual erosivity R factor (measured as EI30 or the rainfall Energy x max 30 min rainfall Intensity) is equal to 2425.1. The measured soil infiltration rate value of 23 mm/h was used for the whole area as the only available measured value (Sheridan 2001). Figure 33.12 shows the digital elevation map of the rehabilitated area and the mean annual erosion rates. Under the condition simulated, erosion rates would be low over most of the area, except where slopes were very steep on either side of the gully running through the center of the northern and

33

Issues and Challenges in the Rehabilitation and Sustainable Use of …

Fig. 33.10 The flowchart for MINErosion 3.4

Fig. 33.11 Example of mean annual soil loss output pages from MINErosion 3.4

533

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H. B. So et al.

southern areas of the rehabilitated area at Curragh. Although vegetative cover reduced erosion, it was not adequate to protect steep slopes where soil loss rates still reached 150 t/ (ha
a). However, as the gully outlet is closed, sediment is prevented from discharging into the surrounding areas. The two models are freely available from the authors (h.so@griffith.edu.au, [email protected]) or downloaded from the following link: https://www.dropbox.com/s/ xd9hkm9r2zayp4l/MINErsion42.exe?dl=0.

33.4

Summary

The most common form of mining in Australia is open cut operation while underground mining has become less common. Land is disturbed due to mining excavations, waste dumps, infrastructure and tailings storage facilities. Soils are compacted, eroded, buried, stored, dug up and relocated or altered in their physical and chemical properties. New landforms with increased average slope are created by waste rock dumps, by tailings dams and by pits which increases the

risk of erosion and run-off. The new landforms, particularly mine pits and tailing dams alter groundwater as well as surface water hydrology. Biota is removed or otherwise damaged. In addition to the altered site water balance, nutrient cycling, biodiversity and resilience of vegetation are all altered by mine site disturbance. Exposing sediments and rocks to water and oxygen by either removal of overburden or by ore processing and grinding of rock triggers weathering processes which can accelerate the release of salts or acid rock drainage that may have severe detrimental e ffects to the environment if not controlled. Disturbance on the mine site may also have off-site impacts due to the increase in run-off and sediment loads, and groundwater discharge may have increased acidity, metal and salt loading if acid sulfate materials are not properly stored or if saline sediments are exposed as waste material to the elements. Despite the range of disturbances produced by mining, restoration after mining has generated some outstanding examples of ecosystem restoration on extremely degraded land.

Fig. 33.12 The digital elevation map (left) and the predicted mean annual erosion rates (right) from the rehabilitated area on the Curragh Minesites in Central Queensland

33

Issues and Challenges in the Rehabilitation and Sustainable Use of …

The extensive waste rock dumps following open-cut coalmining in Queensland and NSW are generally saline and dispersive, while some also may release acid rock drainage. The restoration of these steep post-mining landscapes requires the reduction of slope gradients and lengths to stabilize these slopes against erosion by water, followed by top-soiling where suitable material is available for this purpose. Tools have been developed to ① assist mine sites to derive parameters (slope gradient, slope length and vegetation cover) that can be used to develop landscapes that result in acceptable erosion rates (MINErosion 3.4) and ② predict the erosion patterns and rates from the constructed post-mining landscape (MINErosion 4.1).

References Anderson JA, Bell RW, Phillips IR (2011) Bauxite residue fines added residue sands enhance plant growth potential-a glasshouse study. J Soils Sediments 11:889–902 Australian Government (2016a) Leading practice sustainable development program for the mining industry: tailings management. Canberra,119p Australian Government (2016b) Leading practice sustainable development program for the mining industry: preventing acid and metalliferous drainage. Canberra, 212p Bari MA, Ruprecht JK (2003) Water yield response to land use change in South-West Western Australia, salinity and land use impacts series Report No. SLUI 31. Department of Environment: Perth, Australia Baumgartl T, Glenn V (2013) Returning productivity of Australian prime agricultural land after mining: how international experiences in rehabilitation may show the way forward. AUSIMM Sustain News:6–8 Baumgartl T, Richards BG (2012) Evaporation and salt transport under variable climatic conditions. In: Life-of-mine conference Brisbane QLD, 28–30 Sept 2016, pp 179–186 Bell RW (2013) Land restoration, principles. In: Sven Erik Jorgenson (eds) Encyclopedia of environmental management, vol III. Taylor and Francis, New York, pp 1621–1626. https://doi.org/10.1081/EEEM-120046433 Buchanan SJ, So HB, Kopittke PM et al (2010) Influence of texture in bauxite residues on void ratio, water holding characteristics, and penetration resistance. Geoderma 158:421–426 Carroll C, Pink L, Burger P (2004) Coalmine rehabilitation: a long term erosion and water quality study on central Queensland coalmines. In: 13th International soil conservation organization conference, conserving soil and water for society: sharing solutions, July 2004 (ISCO 2004). Brisbane Chabay I, Frick M, Helgeson J (2015) Land restoration reclaiming landscapes for a sustainable future. Elsevier Science Croton JT, Reed AJ (2007) Hydrology and bauxite mining on the Darling Plateau. Restor Ecol 15:S40–S47 DEHP (2014) User guide EHP financial assurance calculator. EM1268
Version 3 State of Queensland DEHP (2016) Guideline financial assurance under the Environmental Protection Act 1994 ESR/2015/1758
Version 3.00, Effective: 4 MAR 16 State of Queensland

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Domagala J, Wilson I (2007) Land: mining disturbance. In: Freeman J, Webber W (eds) State of the environment Queensland 2007. Brisbane Farrell TR, Kratzing DC (1996) Environmental Effects. In: Mulligan D (ed) Environmental management in the Australian minerals and energy industries: principles and practices. UNSW Press in association with the Australian Minerals and Energy Environment Foundation, 793p Flanagan DC, Laflan JM (1997) The USDA Water Erosion Prediction Project (WEPP). Eurasian Soil Sci 30:524–530 Gardner JH, Bell DT (2007) Bauxite mining restoration by alcoa world alumina Australia in Western Australia: social, political, historical, and environmental contexts. Restor Ecol 15:S3–S10 Geoscience Australia (2017) Australian Atlas of Mineral resources, mines and processing centers. www.australianminesatlas.com.au. Retrieved Aug 2017 Grant CD, Ward SC, Morley SC (2007) Return of ecosystem function to restored bauxite mines in Western Australia. Restor Ecol 15:S94– S103 Hobbs RJ, Norton DA (1996) Towards a conceptual framework for restoration ecology. Restor Ecol 4:93–110 Huang L, Baumgartl T, Mulligan D (2012) Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings. Ann Bot. https://doi.org/10.1093/aob/mcs115 Khalifa AM (2010) MINErosion 4: a user-friendly catchment/ landscape erosion prediction model for post mining sites in Central Queensland. Ph.D thesis, Griffith University, Nathan, Queensland, Australia Koch JM (2007) Alcoa’s mining and restoration process in south western Australia. Restor Ecol 15:S11–S16 Ni CY, Bell RW, McGrath W et al (2014) Amelioration of soil chemical constraints for revegetation on gold oxide processing residues. Ecol Eng 64:66–76 Onstadt CA, Foster GR (1975) Erosion modeling on a watershed. Trans Am Soc Civ Eng 26(1102–4):1108 Renard KG, Foster GR, Weesies GA et al (1991) Revised universal soil loss equation. J Soil Water Cons 46:30–33 Robinson DA, Lebron I, Vereecken H (2009) On the definition of the natural capital of soils: a framework for description, evaluation, and monitoring. Soil Sci Soc Am J 73:1904–1911 Sheridan GJ (2001) Predicting hillslope scale erodibility and erosion on disturbed landscapes from laboratory scale measurements. Ph.D thesis, University of Queensland Sheridan GJ, So HB, Loch RJ et al (2000) Estimation of erosion model erodibility parameters from media properties. Special Issue: Aust J Soil Res 38:265–284 So H B, Khalifa A, Carroll C et al (2011) Tools for designing post-mining landscapes with acceptable erosion risk and discharges on the receiving environment. In: Proceedings international symposium on erosion and landscape evolution, Anchorage, Alaska, USA. CD Rom American Society of Agricultural and Biological Engineers (ASABE) Unger C, Lechner AM, Glenn V et al (2012) Mapping and prioritising rehabilitation of abandoned mines in Australia. In: Proceedings life-of-mine conference, Brisbane QLD, 10–12 July 2012, pp 259– 265 Williams DJ (1996) Management of solid wastes. In: Mulligan DR (ed) Environmental management in the Australian minerals and energy indusries. Principles and Practices. UNSW Press and AMEEF, pp 157–188 Wishmeyer WH, Smith DD (1960) A universal soil-loss equation to guide conservation farm planning. Trans Int Congr Soil Sci 7:418– 425

Issues and Challenges in the Sustainable Use of Soil and Water Resources in Australian Agricultural Lands

34

Chris Carroll, Calvin W. Rose, Richard Greene, Brian Murphy, Ram Dalal, Kwong Y. Chan, and Hwat B. So

34.1

Introduction

Following the arrival of the first fleet in 1788 clearing of land was one of the first acts undertaken, disturbing and destroying the equilibrium of the aboriginal communities and landscape that had existed for thousands of years (www. aboriginalheritage.org). The climate, soils and environment faced by the early settlers was very different to what they had previously experienced in Europe, given Australia is the driest inhabited continent in the world, with 70% of it either arid (average annual rainfall of 250 mm or less), or semi-arid land (average annual rainfall between 250 and 350 mm) (State of the Environment SOE 2011) (Fig. 34.1). Subsequent land clearing following settlement and lack of experience with farming within such a variable climate and on such unfamiliar soils has resulted in many forms of land degradation C. Carroll (&)
C. W. Rose Australian Rivers Institute, Griffith University, Nathan, Qld 4111, Australia e-mail: c.carroll@griffith.edu.au C. W. Rose e-mail: c.rose@griffith.edu.au R. Greene Fenner School of Environment and Society, Australian National University, Canberra, ACT, Australia e-mail: [email protected] B. Murphy Science Division, DepartmentofPlanningIndustryandEnvironment. NSW, Sydney, New South Wales, Australia R. Dalal School of Agriculture and Food Sciences, University of Queensland, Brisbane, Qld 4001, Australia e-mail: [email protected] K. Y. Chan Beecroft, NSW 2119, Australia H. B. So Enviromental Futures Research Centre, Griffith University, Nathan, Qld 4111, Australia

within Australia; increased soil and wind erosion, soil acidification, soil salinization, and degradation of soil structure, soil organic matter and water quality. The Australian National Soil Research, Development and Extension (NSRDE) Strategy (2014) have identified soil security as a major concern with the maintenance and improvement of the global soil resource to produce food, fibre and the protection and maintenance of fresh water, biodiversity, and ecosystem services (McBratney et al. 2014). Since European settlement there has been extensive land clearing, with almost 40% of native forest cleared, and the remaining vegetation highly fragmented. As European colonists expanded in the late 18th and the early 19th centuries, deforestation occurred mainly on the most fertile soils nearest to the coast. In the 1950s, south western Western Australia was largely cleared for wheat production. Since the 1970s, the greatest rates of forest clearance have been in south-eastern Queensland, central Queensland where extensive areas of Brigalow land (dominant species Acacharpophylla) was undertaken (Cowie et al. 2007) and northern New South Wales, with Victoria the most cleared state overall (Bradshaw 2012). Livestock grazing of native vegetation is now the dominant land use on 45% of the land area, and grazing on modified pastures conducted on a further 9%. Dryland cropping is practiced on approximately 4% of Australian land area, forestry 1.3%, irrigated and intensive agriculture 0.29 dS/m) and >0.2% (for clay loams and clays) (EC1∶5 > 0.59 dS/m); and Category 2-Subsoil salinity when NaCl concentration is >0.3% (> 0.88 dS/m) in the B horizon or below 20 cm. For Sodicity, Northcote and Skene (1972) proposed that soils with an ESP of 15% as strongly sodic. These sodicity criteria are consistent with those for the Australian Soil Classification (Isbell 2016). The combination of salinity and sodicity categories are used to determine whether the soil is saline, sodic or saline-sodic. Northcote and Skene (1972) criteria of salinity and sodicity is the most widely used and was used to develop a map of the saline and sodic soils for Australia (Fig. 34.5).

34.4.2 Changing Land Use and Degradation Through Soil Salinization and Sodification Changing land use from native vegetation to cropping and annual pastures alters the hydrology of landscapes by increasing the amount of deep drainage into the deeper soil layers, the regolith and the fractured rock beneath the soil. This will change the amount of water flowing through the landscape, increasing the volume of water discharged onto lower slopes, depressions and water tables and bringing with it salt to the surface (secondary or transient salinity). Example of conceptual models for the formation of salinity is given by Ward et al. (1998), Clarke et al. (2002), and Shimojima et al. (2016). Secondary salinization followed by leaching of the excess salt will result in the formation of sodic soils.

34.4.3 The Extent and Impact of Salinity and Sodicity in Rangeland and Cropping Lands

ECe ¼ ð5=saturated moisture content of the soilÞ  ECð1 : 5Þ

where ECe and EC (1∶5) are in dS/m and the saturated moisture content of the soil is in g/g. The conversion of EC (1∶5) to ECe can be slightly modified when sparingly soluble salts such as gypsum are present in the soil (Slavich and Petersen 1993; Shaw 1999). The criteria to identify saline soils have been defined by various authors. Northcote and Skene (1972) proposed the following categories to map saline soils in Australia: Category 0-Non-saline with no salinity in either the surface and

Salinity and sodicity can develop by different processes in soils and have different impacts on agriculture and the environment that requires different management strategies to minimise their impacts. Salinization is the accumulation of soluble salts, primarily sodium chloride, in soil and is the primary degradation process. In this process, the Na+ acts as a free ion in association primarily with chloride (Cl-), 1983). Other sources of salts are from rock weathering and the connate salts held in Mesozoic marine sediments (Isbell et al. 1983; Shaw et al. 1994).

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C. Carroll et al.

Fig. 34.5 Map of saline and sodic soils in Australia (Northcote and Skene 1972; Isbell et al. 1983) (From the ‘CSIRO Australia, Soil Publication No. 27. Canberra)

Transient or secondary salinization need not affect the whole landscape and is often closely associated with areas of sodic subsoils. The outbreaks of saline land tend to be limited in area, being confined to areas where seepage from the increased recharge is discharged downslope, and salts are concentrated as water is evaporated. While the overall area is not large, the problem can be serious because frequently these outbreaks occur on some of the more productive agricultural land. It indicates the capacity for the salinity problem to contribute significantly to salt loads and water quality (EC) degradation of streams in catchments, and affect infrastructure, and the suitability of water for domestic, industrial as well as for agriculture and irrigation use. As suitable land for cropping is becoming scarce in some parts of Australia, expansion of cropping occurs onto lands but also with sulphate (SO42-), carbonate (CO32-) and bicarbonate (HCO-). Other cations, especially calcium (Ca2+), magnesium (Mg2+) and potassium (K+) can occur as free salts in association with sodium but are usually less important. Large areas of the naturally saline lands occur in the drier rangelands and are associated with inland salt pans and salt

lakes such as Lake Eyre, Lake Torrens and Lake Amadeus. In relation to agricultural production, the high salt concentration in the soil solution affects plant growth through toxicity to plants and reduced water availability. In rangelands in some areas, wind erosion has removed topsoils exposing saline subsoils leading to areas of scalding that can sometimes be extensive (Cunningham 1987). Inland saline lands are a likely source of terrestrial salts that are transported by dust and deposited in other areas of S. E. Australia (Shiga et al. 2011) and salts from the ocean can also be deposited on the landscape in atmospheric precipitation (Blackburn and Mcleod that are naturally sodic and less suitable e.g. sugarcane expansion in Queensland. Where secondary salinity occurs, its reclamation may require the application of gypsum which prevents surface sealing and promotes plant growth and the leaching of excess salt. The largest effects of salinity on agricultural land occur in Western Australia, and also in Victoria, NSW and South Australia, with some important areas affected in Queensland and Tasmania (Table 34.1). In sodicity the primary effect of sodium on soil behaviour is caused by the excess of exchangeable Na+ on the soil’s

34

Issues and Challenges in the Sustainable Use of

547

Fig. 34.6 Effects of soil structural instability associated with SOM degradation and sodicity on aggregate breakdown (slaking and dispersion) and how this affects plant growth and yield through a number of interrelated physical and chemical processes [Extended and adapted from Coughlan (1984), Cook (1988) and So (2013)]

Table 34.1 Estimated areas where agricultural productivity is affected by salinity and sodicity National Land and Water Audit (NLWRA 2001, p 91)

Salinity Estimated area of land used for agricultural production that is affected by dryland salinity in 2000

Sodicity Estimated area of land used for agricultural production that is affected by sodicity in 2000

Area of land used for agricultural production/103 ha

% of land used for agricultural production

Area of land used for agricultural production/103 ha

% of land used for agricultural production

Australian Capital Territory

0

0

1

New South Wales

89

0.1

24,731

38.0

Northern Territory

0

0

11,533

16.2

Queensland

62

0.0

42,191

28.7

South Australia

472

0.8

7635

13.6

3.7

Victoria

287

2.0

8008

56.6

Western Australia

2169

1.8

14,615

12.5

Tasmania

26

1.4

504

27.5

Australia

3105

0.7

109,218

23.1

548

exchange complex relative to exchangeable Ca2+, Mg2+, K+ and acidity. While the amount of free salt modifies the soil’s behaviour (Rengasamy et al. 1984), it is the relative amount of exchangeable Na+ on the exchange complex that dominates the soil’s behaviour. The largest area affected by sodicity occurs in Queensland with smaller areas in the other states with an average of 23% of agricultural lands (Table 34.1) (NLWRA 2001, p 91). The impact of sodicity depends on where sodicity occurs in the profile and the soil structural problems can be especially severe in non-saline, sodic soils. It may be in the surface soil (A horizon) or in the subsoil (B horizon) or both. Sodicity results in slaking (breakdown of macro into micro aggregates