Water Recycling and Water Management [1 ed.] 9781617614224, 9781617613050

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Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved. Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved. Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

WATER RESOURCE PLANNING, DEVELOPMENT AND MANAGEMENT

Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved.

WATER RECYCLING AND WATER MANAGEMENT

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Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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WATER RESOURCE PLANNING, DEVELOPMENT AND MANAGEMENT

WATER RECYCLING AND WATER MANAGEMENT

DANIEL M. CARREY

Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved.

EDITOR

Nova Science Publishers, Inc. New York Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

Copyright © 2011 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers‘ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works.

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Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book. LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA Water recycling and water management / editor, Daniel M. Carrey. p. cm. Includes index. ISBN 978-1-61761-422-4 (E-Book) 1. Water reuse. I. Carrey, Daniel M. TD429.W36 2010 363.6'1--dc22 2010026934

Published by Nova Science Publishers, Inc.  New York

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

CONTENTS Preface

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Chapter 1

vii Runoff Water Harvesting as a Strategy for Increasing Agricultural Production on Hillslope Areas in Arid and Semiarid Zones Osvaldo Salazar and Manuel Casanova

1

Chapter 2

Water Management in Drought-Prone Area M. H. Ali

41

Chapter 3

Water Management in Salt-Affected Areas M. H. Ali

67

Chapter 4

Water Disinfection Using Peracetic Acid M. M. Muñío and J. M. Poyatos

83

Chapter 5

Wastewater Reuse and Recycling in Sub-Saharan Africa: The Case of Nigeria M. C. Obeta, T. C. Nzeadibe, C. K. Ajaero and C. N. Ayogu

107

Chapter 6

The Development of Australia‘s Water Recycling J. C. Radcliffe

Chapter 7

Review on Water Resources Management in the Yellow River Basin Liu Ke, Xu Zongxue and Ramasamy Jayakumar

145

Groundwater Pollution Due to Agricultural Practices in a Semiarid Area A. Dilek Atasoy and M. Irfan Yesilnacar

161

Elimination of Recalcitrant Compounds from Industrial Wastewater by Photo-Fenton Process J. M. Poyatos, F. Osorio and M. M. Muñío

181

Recycling of Sludge from Water Treatment Plant in Red Ceramics E. M. S. Oliveira, A. G. P. Silva and J. N. F. Holanda

197

Chapter 8

Chapter 9

Chapter 10

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vi

Contents

Chapter 11

Water and International Trade Law: Friends or Foes? Vasiliki-Maria Tzatzaki

Chapter 12

Optimization of Condenser Water Loop in HVAC Systems: Genetic Algorithm Approach R. Uche and E. O. Diemuodeke

237

Financial Analysis of Implementation of Rainwater Utilization System in Modernized Multi-Family Residential Building Daniel Słyś

249

Chapter 13

Chapter 14

Rainwater Uses and Storage Olanike O. Aladenola

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Index

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259 269

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PREFACE Water recycling is former wastewater (sewage) that has been treated to remove solids and certain impurities, and then used in sustainable landscaping irrigation or to recharge groundwater aquifers. This is done for sustainability and water conservation, rather than discharge the treated wastewater to surface waters such as rivers and oceans. Water management is the activity of planning, developing, distributing, managing, an optimum use of water resources defined under water polices and regulations. This book presents topical research data in the study of water recycling and management, including runoff water harvesting for agricultural production in semiarid zones; water disinfection using peracetic acid; wastewater reuse and recycling in sub-Saharan Africa; Australia's water recycling system; as well as the water and international trade law. Chapter 1 - Recent studies suggest that climate change over the next century will affect water cycles all over the world, with precipitation decreases expected for many arid and semiarid regions. This will be particularly critical on hillslope areas under rainfed conditions, where only the amount of rainfall determines the success or failure of agriculture. Under these conditions, scarce and erratic rainfall produces runoff of an intermittent character, while infrequent rain of high intensity increases the soil erosion rate. It has therefore been suggested that agricultural production on hillslope areas combined with runoff water harvesting in arid and semiarid zones can be a viable solution to increase water availability to crop plants. In this water management system, water harvesting involves inducing, collecting, storing and conserving local surface runoff. This water can be used for supplemental irrigation of agricultural systems in rainfed areas, helping to maintain and even increase food production in these regions. This chapter analyses the potential of combining agricultural production with water harvesting in arid and semiarid zones through a comprehensive review of the literature on runoff water harvesting published during the past 25 years, which can be roughly divided into experimental and modelling approaches. The potential synergistic effects of water harvesting combined with agroforestry are illustrated by a practical case study using the results of a pilot experiment carried out in a semiarid region of Chile. Particular attention is devoted to the potential of water harvesting as a measure to mitigate water scarcity for agriculture in arid and semiarid regions under future climate change scenarios. Two main conclusions are reached: The integration of water harvesting with soil management practices is still facing critical problems that have to be overcome in order for the system to mitigate the adverse effects of climate change; and the integration of simulation models and GIS offers a potential synergy that appears to be key to effective

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viii

Daniel M. Carrey

development and planning of water harvesting as a measure to mitigate future increasing water scarcity. Chapter 2 – Water deficit in an area may arise from many factors such as low rainfall, uneven distribution, high losses due to evaporation and runoff, and absence of source of irrigation water. Seasonally dry tropics are spread over parts of 49 countries covering an area of over 20 million km2 in five continents and support more than 600 million people mostly living at subsistence level on small farms and practicing rainfed agriculture to meet their food and fodder requirements. Most of Indian subcontinent falls under the semi-arid tropics where 74% of the arable land is rainfed and contributes only 45% to the national food production. Improved water management will determine the prospects of increasing crop production in such seasonally dry areas, but the management techniques may vary from region to region depending on the amount and distribution of rainfall, nature and properties of soil, crop grown and socio-economic conditions. Chapter 3 – Soil salinization is the accumulation of free salts in soil to such an extent that it leads to degradation of soils and vegetation. The salts originate from the natural weathering of minerals or from fossil salt deposits left from ancient sea beds. Salts accumulate in the soil of arid climates as irrigation water or groundwater seepage evaporates, leaving minerals behind. Irrigation water often contains salts picked up as water moves across the landscape, or the salts may come from human-induced sources such as municipal runoff or water treatment. As water is diverted in a basin, salt levels increase as the water is consumed by transpiration or evaporation. Countries experiencing salt problem include Australia, Argentina, Bangladesh, Canada, India, Pakistan, Thailand, South Africa, Turkey, USA, etc. Understanding the soil-salinization processes and limitations is the key to improvements and helps in taking amelioration measures. Chapter 4 – Water disinfection consists in the deactivation, removal or killing of pathogens in order to avoid their growth and reproduction. If disinfection step is not carried out, diseases such as typhoid and paratyphoid enteric fevers, cholera, hepatitis and diarrhoea can alter human health. A lot of disinfection systems have been developed over the last years, but in general these systems should deactivate all pathogens in the water to be effective. An ideal one is able to provide long term disinfection to all water, safe, with minimum maintenance and economical. Although several methods comply with the conditions exposed above, chlorination is the most commonly used. But chlorine compounds reacts with a lot of substances present in water, as amino acids, ammonia, organic matter, iron, manganese and others. The result of such as reaction variety is an extensive range of disinfection by-products (DBPs) like trihalomethanes (THMs), haloacetic acids (HAAs), chlorophenols, haloketones and chloramines. These DBPs could cause human health problems, endanger aquatic life and stay in the environment for long periods. Some other chemical disinfectants (sodium hypochlorite, chlorine dioxide, hydrogen peroxide, bromine, peroxone, ozone, peracetic acid, etc.) and even physical treatments (ultraviolet light, gamma-rays, heat, sound, etc.) could be used to get disinfected water. Peracetic acid (PAA) is a mixture of acetic acid and hydrogen peroxide in watery solution. Its degradation products are non-toxic and can easily dissolve in water; it is a very powerful oxidant and the oxidation potential outranges that of chlorine and chlorine dioxide. This acid can be applied for the deactivation of a large variety of pathogenic microorganisms,

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Preface

ix

spores and viruses. A great advantage is that its activity is hardly influenced by organic compounds that are present in the water. Nowadays PAA is applied for water purification as a disinfectant and it is suitable for cooling tower water disinfection where it controls Legionella bacteria. This chapter is about the use of peracetic acid as wastewater disinfectant. In general, PAA disinfection is applied to wastewater from secondary or biological treatment. Several factors have been analyzed: contact time and doses for different types of wastewater, effectiveness of the disinfection, combination with other treatments (as ultraviolet light), etc. Chapter 5 – This chapter presents a non-engineering treatment of water recycling so that non-specialists readers will be in a position to understand and appreciate the concept. It is intended to fill a long-felt need at the academic and policy level, and among social and earth scientists, especially in Nigeria, for a straightforward and systematic analysis of the subject. Data from authors‘ fieldwork, secondary sources and government institutions are used to develop this chapter. The authors have made effort to explain the fundamentals of the subject and discuss the evolution, purpose, trends and developments in and the impact of water recycling in the Nigerian and some other developing societies in Sub-Saharan Africa. In addition, the authors have tried to incorporate relevant background information on the problems of water recycling, the socio-cultural issues in water recycling and recent developments in water recycling in Nigeria. Two case studies on the water recycling sector in sub-Saharan Africa are presented. Implications of water recycling on water resource development and management, and achievement of the water and sanitation-related millennium development goals (MDGs) in Nigeria are also examined. Chapter 6 – Australia is a large continent with a diversity of climate, but much of it is arid. The principal high rainfall areas are in tropical northern Australia where population is sparse and development has been limited. Constitutionally, management of water resources is a States/Territories responsibility. With a population of 18.3 million in 1996-7, now expected to increase to 35 million by 2050, there is considerable pressure on Australia‘s water resources. Although reports suggested in the late 1970s that water recycling would become necessary in Australia, there was little take-up of the concept before the late 1990s, but recycling technologies, particularly those membrane based, have since expanded enormously. This has been facilitated by the introduction of new nationally-agreed water policies and financial support from the Australian government. Dual reticulation systems are in place in parts of Sydney, Melbourne and Adelaide. A major investment has been made in South-East Queensland to add recycled water to the drinking water system via three Advanced Water Recycling Plants capable of feeding the Wivenhoe Reservoir, Brisbane‘s principal water storage. Managed aquifer recharge is being introduced where the hydrogeology is appropriate. Stormwater is increasingly seen as an additional water resource and has been taken into the drinking water system in Orange, New South Wales. New National Water Quality Management Strategy guidelines have been accepted for recycled water including augmentation of drinking water supplies. Since 2003, there has been a commitment to establish six desalination plants for five of Australian capital cities – those in Perth, SE Queensland and Sydney are already operating. Yet there remains some concern in governments about the wider community acceptance of recycled water for drinking. Chapter 7 – As is often called the mother river of China, the Yellow River, with a catchment area of 795,000 km2, accommodates 12% of the Chinese population. It flows across nine provinces in the arid and semi-arid areas of China. In recent years, the basin has

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experienced accelerated economic development, led by factors such as industrialization and urbanization. Nevertheless, as being celebrated as reasons for economic success, urbanization, industrialization, have brought challenges to water resources in the Yellow River Basin from both quantity and quality perspectives. The amount of untreated industrial sewage dumped in the Yellow River has been doubled since the 1980‘s to 4.2 billion m3 per year, consequently, only 60% of the river course is fit for drinking purposes. Moreover, climate variabilities increased probabilities of extreme event such as droughts and floods. Plus, it has brought a general trend of reduction in terms of water provision in the basin. For instance, multi-year average runoff in the Yellow River has been reduced by 8% from 1956 to 2000, while average yearly temperature has been increased by 0.6 Celsius in the same period. Contrary to the reduced water supply, demands for water have been increasing from 10 billion m3 in 1949 to 37.5 billion m3 in 2006. All such challenges call for sustainable water resources management, as one of the solutions to balance the dwindled water supply with increased demands, and ensure water security and sustainability in the Yellow River basin. This paper is aimed to investigate water resources management in the Yellow River basin, examining its development course, current regime, identify the gaps and provide improvement recommendations. Chapter 8 – The increasing population and the gradually raising food consumption are two important phenomenon facient the water and the soil pollution. Excessive and uncontrolled irrigation and extensive agricultural using of chemicals in the arid and semi-arid regions play the important roles on the pollution. The aim of the study is to determine the polluting effects of the agricultural practices (the pesticide-nitrate contamination, water quality problem, corrosivity and salinity in the groundwater) in Harran Plain in semi-arid Southeastern Anatolian Region, Turkey. The groundwater quality in Harran Plain before and after the irrigation period was compared in the research. The results shown that, with regard to typical characteristics of the Harran soils, the ground water was contaminated with nitrate and pesticide (endosulfan). The corrosion tendency of the groundwater is another quality problem derived from the high soluble salts leaching through the soil profiles. The irrigation without drainage systems caused the rising of soil water level, the increasing of the soil salinity and degrading of the groundwater quality. The extensive use of pesticides/fertilizers and excessive irrigation should be avoided, farmers training must be carried out and the pest management techniques/practices must be improved immediately in a more environmentally sustainable manner. Chapter 9 – Water pollution not only affects drinking water, but also rivers, lakes and oceans all over the world and is affecting both aquatic and terrestrial life. For these reasons, water pollution control is an important subject to face up for the governments and industries all around the world. The main problem of the wastewater produced by the industries is the huge amount of recalcitrant compounds which make that water an important source of contamination. These compounds cannot be degraded only by a single biological treatment, so new techniques have been developed to this aim. Advanced oxidation processes (AOPs) are one of the most effective methods to degrade those compounds. Lots of processes are included in the AOPs group, but photo-Fenton method is usually the most used. The article describes and analyses the effect of photo-Fenton process when degrading wastewater from different types of industries with several types of recalcitrant contaminants. Chapter 10 – The municipal water treatment plants (WTP) are units used to give chemical and physical treatments to raw fresh-water. In general, the treatment operations

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Preface

xi

involve the following steps: i) pre-settlement of the raw water; ii) coagulation/flocculation; iii) decantation; iv) settlement; v) filtration; and vi) chlorination and pH control. In these operations, the WTPs also produce huge amounts of wastes in form of sludge. The volume of such wastes is expected to continuously increase. The WTP waste is classified in accordance with environmental regulations as a non-inert waste material. Thus, the disposal of sludges produced by WTPs in an environmentally safe way is one more challenge to be faced by the water treatment companies. Nowadays, a widely used method of recycling wastes is their incorporation into ceramic materials. This chapter focuses on the recycling of a sludge produced by water treatment plant as an alternative raw material for manufacture of red ceramics. This recycling way is environmentally correct and can contribute to conservation of natural resources and waste management. Chapter 11 – A few years ago, water and international trade law barely knew each other. Water is a vital source for life, taken for granted and overexploited. International trade law is expanding, ignoring borders and nationalities. However, water scarcity, due to climate change and population growth, became the connecting link between water and international trade law. International trade on water, regardless of whether it is bottled or bulk, is a reality and raises questions of its regulation. Can water be a commodity? Which rules are applicable to water imports or exports? The aforementioned are some of the questions that this paper is addresses. In particular, it argues that water is certainly a product in its bottled form and therefore, is subject to the rules of international trade. Moreover, it deals with bulk water trade and further supports that, despite the debate, bulk water should also be considered a commodity, when transferred. Finally, as for the future perspectives, the issue of virtual water is considered. These issues are examined within the legal framework provided by the World Trade Organization, aiming at highlighting the ‗friendship‘ between water and international trade law. Chapter 12 – Energy optimization of a condenser water loop operation in heating, ventilation and air conditioning (HVAC) system has been done. The objective function, which minimizes the operating costs, was formulated on the analysis of thermal interaction between the cooling tower and chillers. The Genetic Algorithm (GA) was used to optimize the changes of outdoor environment and indoor cooling load based on the objective function formulated. The approach has the capability of solving the combinatorial optimization problem with both discrete variables and continuous variable. Chapter 13 – In this chapter, results of a financial analysis are presented for an investment consisting in modernization of multi-family residential building water supply facilities through introduction of a rainwater collection, storage and utilization system. The related calculations were carried out with the use of a simulation system representing rainwater utilization in residential buildings that was additionally extended with functions performing calculations of economic ratios. The calculations were based on archival data concerning precipitation levels. In the analysis, both currently applicable municipal water prices and those obtained as a result of forecasting were taken into account. Chapter 14 – Rainwater harvesting (RWH) has been in existence for a long period of time, it precedes the large scale public water systems. It is becoming more popular as worldwide pressure on water resources is mounting due to rapidly increasing populations and changing climate. Rainwater has been identified as potential water source that can be used for activities requiring low water quality. Rainwater harvesting reduces stormwater runoff and dependence on potable water, it lowers the costs and energy associated with treating and

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pumping water in centralized water supply systems. Rooftop rainwater harvesting provides water for household, industries and public facilities. RWH is promoted in various countries through policies and efforts to reduce the cost of rainwater storage tanks. Local cheap construction materials have been tested and found suitable for constructing rainwater storage tanks. However the cost of rainwater storage tank that will meet all non potable needs cannot be afforded by household in developing countries.

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Chapter 1

RUNOFF WATER HARVESTING AS A STRATEGY FOR INCREASING AGRICULTURAL PRODUCTION ON HILLSLOPE AREAS IN ARID AND SEMIARID ZONES 1

Osvaldo Salazar1,2 and Manuel Casanova1 Departamento de Ingeniería y Suelos, Facultad de Ciencias Agronómicas, Universidad de Chile, Casilla 1004, Santiago, Chile 2 Copenhagen University, Faculty of Life Sciences, Department of Basic Sciences and Environment, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark

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ABSTRACT Recent studies suggest that climate change over the next century will affect water cycles all over the world, with precipitation decreases expected for many arid and semiarid regions. This will be particularly critical on hillslope areas under rainfed conditions, where only the amount of rainfall determines the success or failure of agriculture. Under these conditions, scarce and erratic rainfall produces runoff of an intermittent character, while infrequent rain of high intensity increases the soil erosion rate. It has therefore been suggested that agricultural production on hillslope areas combined with runoff water harvesting in arid and semiarid zones can be a viable solution to increase water availability to crop plants. In this water management system, water harvesting involves inducing, collecting, storing and conserving local surface runoff. This water can be used for supplemental irrigation of agricultural systems in rainfed areas, helping to maintain and even increase food production in these regions. This chapter analyses the potential of combining agricultural production with water harvesting in arid and semiarid zones through a comprehensive review of the literature on runoff water harvesting published during the past 25 years, which can be roughly divided into experimental and modelling approaches. The potential synergistic effects of water harvesting combined with agroforestry are illustrated by a practical case study using the results of a pilot experiment carried out in a semiarid region of Chile. 

Corresponding authors (e-mail: [email protected]; [email protected])

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Osvaldo Salazar and Manuel Casanova Particular attention is devoted to the potential of water harvesting as a measure to mitigate water scarcity for agriculture in arid and semiarid regions under future climate change scenarios. Two main conclusions are reached: The integration of water harvesting with soil management practices is still facing critical problems that have to be overcome in order for the system to mitigate the adverse effects of climate change; and the integration of simulation models and GIS offers a potential synergy that appears to be key to effective development and planning of water harvesting as a measure to mitigate future increasing water scarcity.

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INTRODUCTION The water in arid and semiarid zones is a scarce natural resource with a high value, especially for agricultural activities, and rainfall amounts are low and erratically distributed. Arid and semiarid zones are usually characterised by small-scale subsistence rainfed agriculture, which has low and unreliable productivity. Recent studies suggest that climate change over the next century will affect water cycles all over the world. This change will be particularly serious for many arid and semiarid regions, which are predicted to suffer a decrease in precipitation over coming decades (Kundzewicz et al., 2007; World Water Council, 2009). This will create real difficulties for water supplies on hillslope areas under rainfed conditions in arid and semiarid regions, which usually do not have access to irrigation systems and only the amount of rainfall determines the success or failure of agricultural production. In addition, rainfall is lost almost completely through direct evaporation or uncontrolled runoff and without intervention is nearly useless in these areas (Oweis et al., 1999). Rockström et al. (2010) noted that in these regions crop yields are very variable, not due to lack of water per se but rather due to inefficient management of water, soils and crops. There is evidence to suggest that research is urgently needed on low-input water management techniques to improve the productivity of agricultural activities despite increasing pressure on water resources and uncertainty due to climate change in arid and semiarid regions. Agricultural production on hillslope areas combined with runoff water harvesting can be a viable solution to increase and sustain food production in arid and semiarid regions (Bhushan et al. 1992; Tabor, 1995; Li et al., 2000a; Rockström et al., 2010). There is a wealth of information available on the benefits of adopting runoff water harvesting in drylands, e.g. Oweis and Hachum (2006) concluded that water harvesting is the only option for financially viable agricultural and environmental protection in these areas. Moreover, under these conditions the scarce and erratic rainfall produces runoff of an intermittent character, and infrequent rain of high intensity increases the soil erosion rate. Thus, runoff water harvesting may also help to control soil erosion, which is one of the major forms of soil degradation in arid and semiarid regions (Laryea, 1992; Rama Mohan Rao et al., 1999; Zhao et al., 2009). It is widely accepted that water harvesting reduces rainfall runoff and resulting downstream erosion because instead of runoff being left to cause erosion, it is harvested and utilised (Critchley et al., 1991; Tabor, 1995). Moreover, Oweis and Hachum (2009) reported that water harvesting can improve the vegetative cover, increase the carrying grazing capacity and help halt environmental degradation in dryland areas suffering from desertification, which is one of most pressing environmental problems in these regions. In addition, Lal (2008) recommended runoff water harvesting as a management practice that may increase the soil carbon pool and thus minimise the extent and severity of climate change and mitigate its

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production…

3

impact on agricultural productivity and global food security. Yuen et al. (2001) reported that runoff water harvesting provides a sustainable way of improving the living environment in aboriginal communities in arid areas of Australia, which is a critical factor in reducing their health problems. However, Hutchinson et al. (2010) noted that water harvesting techniques can mainly be successful where the costs of sacrifice land and sufficient labour to maintain the infrastructure are low relative to the value of the harvested water and its produce. Boers and Ben-Asher (1982) defined water harvesting as a method for inducing, collecting, storing and conserving local surface runoff for agriculture, while Oweis et al. (1999) defined it as the process of concentrating rainfall as runoff from a larger area for use in a smaller basin area. Boers and Ben-Asher (1982) noted that water harvesting methods have three characteristics in common: i) They are applied in arid and semiarid zones where runoff has a intermittent pattern; ii) they depend upon local water such as surface runoff, stream flow etc. and do not include storage of river water or mining of groundwater; and iii) they are relatively small-scale operations in terms of catchment area, volume storage and capital investment. On the other hand, Oweis et al. (1999) concluded that water harvesting is distinguished from irrigation by three key features: i) The runoff area is contiguous with the benefiting basin area and is relatively small; ii) application to the basin area is essentially uncontrolled because the objective is simply to capture as much water as possible and store it in the soil profile of basin areas or in some type of reservoir; and iii) water harvesting can be used to concentrate rainfall for purposes other than crop production. Critchley et al. (1991) noted that although in a year of severe drought there may be no runoff to collect, an efficient water harvesting system will improve plant growth in the majority of years. Water harvesting is an ancient concept that has been used in the past by native communities in arid and semiarid areas around the world, which may provide insights into potential solutions to current and future water resource challenges in these regions (Cowan, 2007). Some examples of these ancient water harvesting systems include ‗khadin‘ in India (Pandey et al., 2003), a system similar to the Indian ‗khadin‘ in Peru (Mächtle et al., 2009), ‗mahafir‘ in Jordan (Agnew et al., 1995), ‗sabeans‘ in Yemen (Brunner and Haefner, 1986), ‗takyrs‘ in Turkmenistan (Fleskens et al., 2007), ‗teras‘ in Sudan (Van Dijk and Ahmed, 1993), ‗qanats‘ in Iran (Ahmadi et al., 2010), and ‗stone mounds‘ and ‗shikim‘ in the Negev desert in Israel (Lavee et al., 1997; Eldridge et al., 2002). Moreover, water harvesting systems over larger areas were also applied several thousand years ago, e.g. ‗marib‘ in North Yemen (Brunner and Haefner, 1986) and systems in New Mexico, Pakistan, Tunisia (‗jessour‘), Kenya, China, etc. (Reij et al., 1988). Some of these indigenous systems and many other techniques are still in use, such as ‗jessour‘ and ‗meskat‘ in Tunisia; ‗tabia‘ in Libya; ‗cisterns‘ in north Egypt; and ‗hafaer‘ in Jordan, Syria and Sudan (Oweis, 2005). Thus as noted by Pandey et al. (2003), over thousand of years people living in different areas of the world have developed a system of runoff water harvesting rather than migrating to new areas as an adaptation to climate change. Although water harvesting techniques have been used from historical times and have also been evaluated in a number of field experiments on dryland around the world during the past 25 years, many of them are not extensively applied. Some runoff water harvesting systems employ the option of storing water in reservoirs to meet the needs of plants in stress periods (Vittal et al., 1988). However, there are two major constraints to successful construction of water storage structures in arid and semiarid regions: seepage losses and excessive evaporation from surface reservoirs (Laryea, 1992). Moreover,

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Osvaldo Salazar and Manuel Casanova

to avoid deep percolation in reservoirs it is necessary to seal the structures, increasing the costs of the system. One possible and relatively low-cost way to tackle water losses is to store harvested water in the soil profile in order to minimise evaporative losses. This chapter focuses mainly on methods of runoff water harvesting that use the soil as a water reservoir. There are other comprehensive reviews available that deal with this issue, such as Frasier and Myers‘s Handbook of Water Harvesting (1983), Reij et al.‘s Water Harvesting for Plant Production (1988) and Critchley et al.‘s Water Harvesting: A Manual for the Design and Construction of Water Harvesting Schemes for Plant Production (1991). However, this chapter mainly reviews later literature on runoff water harvesting, published during the past 25 years, and attention is focused on the potential of water harvesting as a measure to mitigate water scarcity in agriculture on hillslope areas in arid and semiarid zones under the future climate change scenarios. Research into water harvesting during the past 25 years can be roughly grouped into experimental or modelling approaches. The modelling approaches have tended to focus on identifying areas that could be used for water harvesting projects, usually with the help of Geographic Information System (GIS), while the experimental field studies have attempted to link water harvesting with soil management practices, such as tillage, nutrient and crop residue management and choice of crop rotation. This chapter concludes by examining the potential synergistic effects of water harvesting combined with an agroforestry system using the results of pilot experiments on combined agroforestry-water harvesting carried out in a semiarid zone of Chile.

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FACTORS AFFECTING RUNOFF WATER HARVESTING DESIGN The appropriate choice and design of a water harvesting system depend on factors such as climate, soil and land topography (Oweis et al., 1999). It is necessary to collect data on parameters related to these factors in order to answer the three main questions for any water harvesting design: How much runoff will reach the basin area? What are the water requirements of crops and/or trees? and How much water can be stored in the soil? (Tauer et al., 1991). The parameters relating to climate that must be considered before implementation of a water harvesting system are mainly rainfall amount, intensity and distribution. Oram and de Haan (1995) noted that a lower precipitation limit ranging between 100 and 150 mm per year is critical for the success of water harvesting in arid zones with a winter rainfall climate, whereas 200 mm per year is needed for areas with a summer rainfall climate. Therefore, a comprehensive study of the local climate conditions is generally needed prior to implementation of a water harvesting system (Rappold, 2005). The relevant parameter in terms of the soil is the texture. Soils that develop a crust on the surface as a result of the impact of raindrops may be more suitable for runoff areas, while fine-textured soils, which can store more water than coarse-textured soils, may be more preferable for basin areas (Boers et al., 1986a; Previati et al., 2010). In a macrocatchment water harvesting experiment in Pakistan, Khan et al. (2009) studied how different soil texture (silty clay, clay loam, silty clay loam, silt loam and loam) in the basin area affected the grain and straw yield of a wheat crop. They found that the highest wheat grain and straw yields were obtained from loam soils and the lowest from silty clay soils as a result of relatively heavy rainfall in the months prior to harvest of the wheat crop. Similarly, Critchley et al.

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(1991) reported that loam soils are best suited to water harvesting systems since they are ideal for plant growth in terms of nutrient supply, biological activity and nutrient- and waterholding capacity. On the other hand, hydraulic soil properties affect the runoff and infiltration rates, which should be considered in the water harvesting design. For example, the soil moisture content, which is affected by soil hydraulic conductivity (K), has been shown to act as a threshold for runoff generation (Cammeraat, 2004). The important parameters to consider in the implementation of a water harvesting system in terms of land topography include the size of the runoff area and the length and gradient of the slope because these determine the runoff water supply to the basin area and also affect the rate of erosion (Oram and de Haan, 1995). Topography factors are also often directly correlated with soil properties, e.g. Casanova et al. (2000) reported a tendency for an increase in K at field level with increasing slope gradient. This is because fine-textured soils are often found at the bottom of slopes and have small water intake and large runoff potential.

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METHODS OF RUNOFF WATER HARVESTING Runoff water harvesting systems tend to be very site-specific. According to Pereira et al. (2009), water harvesting for crops varies from one region to another according to indigenous knowledge, land form, soil type, runoff intensity and the crops to be irrigated. In general, a distinction is made between inter-row water harvesting, where water is collected at the location in which it is used; microcatchment water harvesting, where rain is collected in part of the area and infiltrated into a downstream cropping zone; macrocatchment water harvesting, where runoff water is collected from large areas to be stored in earth dam reservoirs or tanks and used to irrigate downstream fields; and floodwater diversion systems, also called spate irrigation systems, where appropriate structures in the river bed divert the flood runoff in a controlled manner to nearby cropped fields. Runoff water harvesting systems consist of two basic components: the collection of water from a ‗runoff area‘ and its storage for future use in a ‗basin area‘. A number of runoff water harvesting specifications have been reported in the literature and deal with factors such as size, design, etc. Some examples are presented in Figures 1 and 2. This chapter does not introduce a new classification system but instead uses the most common classification according to the size of the runoff water harvesting system, grouping these into microcatchment and macrocatchment systems.

Microcatchment Water Harvesting Boers and Ben-Asher (1982) defined microcatchment water harvesting as a method to collect surface runoff from a runoff area over a distance of less than 100 m and store it in the rootzone of an adjacent infiltration basin area in order to supply crop water requirements. They noted that the overall aim of microcatchment water harvesting is to store sufficient runoff water in the rootzone below the basin area during the rainy season to meet the water requirement of crops or trees during the growing season.

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Figure 1. Classification of runoff harvesting systems a) adapted from Oweis et al. (1999) and b) adapted from Critchley et al. (1991).

Figure 2. Classification of major rainwater harvesting systems in dryland areas (from Oweis et al., 2001).

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Figure 3. Water balance components of runoff and basin areas during the rainy and growing seasons in a microcatchment water harvesting system (adapted from Boers et al., 1986a). R: runoff; Pa: rainfall in runoff area; Pb: rainfall in basin area; Ea: evaporation from runoff area; Eb: evaporation from basin area; Da: increase in storage of shallow soil water in the runoff area; T: transpiration by crop or tree; ΔW: increase in soil water storage.

In designing a microcatchment water harvesting system, the hydrological year may be divided into two seasons: the rainy season and the growing season. Boers et al. (1986a) established different water balance equations for microcatchment water harvesting by considering the inputs (rainfall), outputs (evapotranspiration and deep percolation) and time boundaries of the water balance equations, as shown in Table 1 and Figure 3. It is important to note that in these equations the following assumptions were made: Lateral soil water flow below the basin was negligible; during the rainy season trees were inactive; open water evaporation was negligible because water remained in the infiltration basin for short periods in winter; during the growing season there was no rainfall and no runoff; all temporary shallow water stored in the runoff area evaporated during the growing season; deep percolation in the basin area ceased at the end of the rainy season; and during the growing season no further evaporation occurred in the basin area. Boers et al. (1986b) proposed that for a given time period, the water balance equation of the basin area in a microcatchment water harvesting system can be represented as: T = Pb + R – Eb – Db – ΔW

(1)

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components for which it was designed using the coefficients shown in Table 2 (Boers et al., 1986a). Table 1. Water balance equations in a microcatchment water harvesting system during the hydrological year (adapted from Boers et al., 1986a) Runoff area Basin area Rainy season R = P a – E a – Da ΔW = R + Pb – Eb – Db Growing season E a = Da ΔW = T R: runoff; Pa: rainfall in runoff area; Pb: rainfall in basin area; Ea: evaporation from runoff area; Eb: evaporation from basin area; Da: increase in storage of shallow soil water in the runoff area; T: transpiration by crop or tree; ΔW: increase in soil water storage.

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Table 2. Coefficients for evaluating the performance of microcatchment water harvesting systems Coefficient

Equation

Considerations

Runoff efficiency (er)

er = R/Pa

Storage efficiency (es)

es = ΔW/(Pb + R)

Microcatchment efficiency (emc)

emc = ΔW/(Pa + Pb)

The er value can be increased by making the catchment are more impervious, reducing infiltration losses in that zone The es value depends on the effective depth of the soil profile. Although es can be increased by enlarging the storage capacity of the basin area, this may cause water in the basin to spread over a large area, thus decreasing the depth of water that would infiltrate The emc value can be increased by considering the recommendations for er and es

Some microcatchment systems are simple and usually consider only a small runoff area constructed around a tree known as ‗negarim‘ (Ojasvi et al., 1999; Sepaskhah and Foolandmand, 2004), whereas other microcatchment techniques include contour furrows (Abau-Zanat et al., 2004), terraces (Fleskens et al., 2005; El Atta and Aref, 2010), and contour, semicircular and trapezoidal bunds. Some studies include a comparison of the performance of different microcatchment systems, e.g. Wang et al. (2008) and Al-Seekh and Mohammad (2009). Four examples of microcatchment systems are shown in Table 3. In China, researchers have developed a microcatchment water harvesting technique called ridge and furrow rainfall harvesting, where the crop is sown in the furrow (basin area) between film-covered ridges (runoff area). Using this system, Xiao et al. (2007) found that it was possible to improve soil water storage and reduce water losses by evaporation. Water harvesting systems considered intermediate between micro- and macrocatchments in terms of size have been classified as mini-catchment or external catchment systems. An example of the external catchment system is the ‗teras‘ technique, which is widespread in semiarid central Sudan (mean annual rainfall of 200-500 mm).

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This water harvesting method aims to conserve water in the soil for crop production, but can also control erosion because it reduces flow velocities to less erosive magnitudes. According to Van Dijk and Ahmed (1993), the ‗teras‘ include two main characteristics: a basin area surrounded by ditches on three sides and a runoff area located at the open side, upslope of the basin area (see Figure 4). The dimensions of the system vary with slope and amount of runoff expected in the basin area, with the base contour ditch ranging in length from 50 to 300 m and the arms from 20 to 200 m. Table 3. Microcatchment system descriptions (adapted from Critchley et al., 1991) Name

Description

‗Negarim‘

A diamond-shaped basin area is surrounded by small earth bunds with an infiltration pit in the lowest corner of each. Runoff is collected from within the basin and stored in the infiltration pit, which is mainly

Figure

used for growing trees or bushes.

Contour bunds

Contour bunds for trees follow the contours, at close spacing, and small earth ties divide the system

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into individual microcatchments.

Contour ridges

These are used for crop production, with ridges following the contours at a spacing of usually 1 to 2 m. Runoff is collected from the uncultivated strip between ridges and stored in a furrow just above the ridges.

Semicircular bunds

Earth embankments are arranged in a semicircle with the tips of the bunds on the contour. The bunds are of varying dimensions and are used mainly for rangeland rehabilitation or fodder production, but also for trees, shrubs and crops.

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Figure 4. Layout of a ‗teras‘ water harvesting system (adapted from Van Dijk and Ahmed, 1993).

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Macrocatchment Water Harvesting Macrocatchment runoff or floodwater farming consists of large-scale rainwater harvesting where the flow collected is immediately diverted to flood-irrigate an adjacent agricultural field. The catchments are usually many square kilometres in size and the runoff water flows through a major ‗wadi‘ (bed of an ephemeral stream), necessitating more complex structures of dams and distribution networks. Critchley et al. (1991) noted that the main characteristics of a macrocatchment system include: Turbulent channel flow harvested either by diversion or by spreading within channel bed/valley floor; runoff stored in the soil profile; runoff/basin area ratio above 10:1; and provision for overflow of excess water. There are two main types: ‗floodwater harvesting‘ within the stream bed, which involves blocking the water flow to inundate the valley bottom of the entire flood plain, forcing the water to infiltrate and using the wetted area for crop production or pasture improvement; and ‗floodwater diversion‘, which involves forcing the ‗wadi‘ water to leave its natural course and conveying it to nearby areas suitable for arable cropping. Oweis and Hachum (2006) noted that the runoff areas are often natural rangeland or mountainous areas, which are usually outside the boundaries of the macrocatchment water harvesting system and beyond the control of farmers using the system. Although runoff efficiency in a macrocatchment system is normally less than for a microcatchment system, the large macrocatchment area ensures that the runoff volume and flow rates are high (Hatibu et al., 2002). However, this sometimes gives rise to problems in managing potentially damaging peak flows during intensive rainfall events, which can cause serious erosion and/or sediment deposition. Another important problem associated with these systems involves water rights and the distribution of water, both between the catchment and

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cultivated areas and between various users in the upstream and downstream areas of the watershed (Oweis, 2005). An integrated watershed development approach can overcome this problem, as discussed later in this chapter. Macrocatchment water harvesting systems have been used since ancient times, e.g. the Nabateans and Byzantines created a network of isolated stations to sustain trade routes in the Negev Desert, involving induced runoff from the upper slopes of a catchment, often through the removal of soil and stones, and either channelling the flow through stone spillways into cisterns or tanks, or spreading it in fields behind terraces and dams for crop production. Thus, to cope with very low rainfall amounts, they showed that it was possible to ‗trade land area for water‘, concentrating the runoff of a comparatively large area into a cistern, small plot or field. Through these very labour-intensive efforts, it was possible to grow forage, food crops and orchards for more than 1,000 years (Hutchinson and Herrmann, 2008). Although some of the principles for microcatchment water harvesting design presented in Table 3 are relevant for macrocatchment design, the latter is a more complex task involving the design of various water harvesting structures, analysis of which is beyond the scope of this review. The reader is referred to Critchley et al. (1991) for detailed descriptions of macrocatchment water harvesting design, the most common of which are:

a. ‘Wadi’-Bed Cultivation This consists of a series of dikes constructed across the ‗wadi‘ or ephemeral channel to retard the runoff water coming down the channel. Excess water flows around the end or over the spillway to the next area, as shown in Figure 5 (Frasier, 2005). The dikes, which are usually made of earth, slow down the flow of floodwater and spread it over the land to be cultivated, thus allowing it to infiltrate (Critchley et al., 1991). Due to the slow water velocity, eroded sediment usually settles in the ‗wadi‘ bed, providing a more fertile seedbed (Hutchinson and Herrmann, 2008). This technique is commonly used with fruit trees and other high-value crops, but it can also be helpful for improving rangelands on marginal soils. b. Jessour ‗Jessour‘ is the Arabic term for a widespread indigenous system in southern Tunisia comprising a hydraulic unit with three main components: a dike or ‗tabia‘, a terrace and an impluvium (Ouessar et al., 2004). The ‗tabia‘ is a barrier made of either soil or stones, or both, created to block runoff and sediment, and sediment accumulation helps increase the water storage capacity of the terraces (Fleskens et al., 2005). The ‗tabia‘ has a spillway, usually made of stone, to allow the release of excess water (Hutchinson and Herrmann, 2008). The terrace is a basin area gradually formed by sedimentation processes, which is planted with trees (e.g. olives, almonds, figures, pomegranates, date palm, etc.) in the neighbourhood of the ‗tabia‘ and crops (e.g. pea, chickpea, lentil, broad bean, barley, wheat) in the remaining areas (Nasri et al., 2004). The impluvium is the area designed for collecting and channelling floodwater, which is contained by the natural watercourses (Ouessar et al., 2004). According to Hutchinson and Herrmann (2008), a series of ‗jessour‘ are usually placed along the ‗wadi‘, which originates from a mountainous catchment. Al-Seekh and Mohammad (2009) reported that this ‗jessour‘ system in the terraces is effective in increasing soil moisture storage, prolonging the growing season for natural vegetation, and decreasing the amount of supplemental irrigation required for growing fruit trees. Figure 6 shows a ‗jessour‘ system.

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Figure 5. Two general methods of water spreading by diversion from an intermittent stream (‗wadi‘) onto adjacent land: a) diversion of an uncontrolled flow over unlevelled land by means of a zigzag series of earthen dikes; and b) diversion of a controlled flow from a detention dam to a series of level basins with concrete- or stone-lined spillways (adapted from Hillel, 1982).

Figure 6. A row of ‗jessour‘ in the south of Tunisia (adapted from El Amami, 1984).

c. Water-Spreading This technique is often referred as floodwater diversion and sometimes as spate irrigation (Critchley et al., 1991). Part of the flow is usually diverted by building a structure across the ‗wadi‘ to raise the water level above the nearby areas to be irrigated, where it is stored solely in the rootzone of the crops (Hutchinson and Herrmann, 2008). Ghazavi et al. (2010) found that water spreading can influence all the area under this operation, with soil properties, vegetation cover, water levels and water quality and even socio-economic factors being altered after the implementation of floods.

d. Large Bunds The large bund system, also called ‗tabia‘, consists of large, semicircular, trapezoidal or open V-shaped long earthen/low rock dams across valleys slowing and spreading floodwater Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

Runoff Water Harvesting as a Strategy for Increasing Agricultural Production… 13 to support trees, shrubs and annual crops (Critchley et al., 1991). These structures are often aligned in long staggered rows facing up the slope and the distance between adjacent bunds on the contour is usually half the length of each bund (Hutchinson and Herrmann, 2008).

RESEARCH INTO WATER HARVESTING IN ARID AND SEMIARID ZONES Extensive research during the past 25 years has documented the effects of runoff water harvesting in increasing water supplies for agricultural production on hillslope areas in arid and semiarid zones. Some examples of the microcatchment and macrocatchment runoff water harvesting systems in practice in different countries are presented in Table 4. Most of these studies have focused on integrating water harvesting techniques with soil management practices in order to study the effects of different factors on water harvesting performance and the economics of water harvesting.

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a. Reducing Infiltration in Runoff Areas A number of studies have evaluated the use of plastic covers and the application of soil amendments, dispersants and sealing materials to reduce infiltration and increase runoff in runoff areas. Ben-Hur (1991) evaluated the effects of application of polymetaphosphate (NaPMP) and sodium tripolyphosphate (STP) on seal formation and runoff rate and found that dispersant agents weakened the stability of the soil aggregates, increased clay dispersion and enhanced seal formation, with NaPMP being more efficient than STP in increasing runoff. In another study, Rauzi et al. (1973) studied the effects of applying salt (NaCl), plastic covered with pea gravel and asphalt-coated roofing felt and found that the roofing felt gave the highest runoff efficiency. Fink et al. (1980) tested the application of paraffin wax to soils to create a water-repellent runoff area and reported an average runoff efficiency of 87% during 7 years. While the use of plastic covers or the application of chemical products to the runoff areas increase the runoff efficiency, the improvement achieved in runoff may not justify the costs unless the water is used for high-value crops or trees (Oweis and Taimeh, 1996). Depending on the soil type, natural sealing of the runoff area may occur over time. For instance, a study in India by Sharma (1986) found that after 7 years, the soil crust formed over the microcatchment surface became more dense and impervious, increasing runoff by 1.3-2.7 times the original level. Similarly, in a macrocatchment experiment in Jordan, AbuAwwad and Shatanawi (1997) found that runoff water harvesting worked best on sloping soils with a surface crust and thus a low infiltration rate. Another less expensive method to increase runoff in runoff areas is to compact the soil surface, but to be effective this practice requires the soil in the area to have a high clay content (Ciuff, 1989).

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b. Increasing Infiltration in Basin Areas It is widely accepted that a higher proportion of collected runoff stored in basin areas remains in the subsoil than in the topsoil (Suleman et al., 1995). Thereafter, one strategy can be increase water infiltration in the basin area and store the water deeper in the soil profile, thus reducing evaporation losses. For example, Abu-Zreig et al. (2000) found that using sand ditches in clay soils could increase the soil water content by intercepting runoff and at same time preventing soil erosion. Yuen et al. (2001) reported similar results using gravel-filled trenches in Australia.

c. Reducing Evaporation and Increasing Water Storage in Basin Areas Another strategy to increase the water use efficiency in water harvesting systems is to include some soil management practices in the basin areas to reduce evaporation losses from soil. Studies evaluating the use of gravel mulch in the basin area for this purpose have found that the gravel reduces loss of water by evaporation and improves crop yield and tree growth (Li et al. 2000b; Li et al. 2006). Similarly, Wang et al. (2009) suggested using straw and gravel/sand as a surface mulch in the basin area to improve rainwater harvesting efficiency and increase crop yield. It is also possible to increase the water-holding capacity of soil in the basin area by applying organic matter, e.g. Zougmoré et al. (2004) found a synergistic effect of combining water harvesting techniques with supply of organic compost, increasing water use efficiency.

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d. Optimum Runoff Area/Basin Area Ratio Water harvesting systems provide ideal sites to study runoff behaviour covering a range of conditions likely to react quickly to rainfall in arid and semi-arid landscapes. A number of studies compare the effects of slope and length of runoff area on water harvest microcatchment water systems. For example Sharma (1986) reported that for a sandy loam soil in arid north-west India, it was possible to harvest 13.3-32.1%, 36.1-45.4% and 26.5-44.3 of rainfall as runoff from 0.5, 5 and 10% slopes, respectively, depending upon the length of runoff area, which ranged from 5 to 15 m. These factors are important in determining the optimum runoff area/basin area ratio, e.g. Schiettecatte et al. (2005) estimated that the runoff area/basin area ratio should be at least 7.4 to provide sufficient water for olive cultivation in an area of Tunisia, with mean annual precipitation of 235 mm. In an area of semiarid Tanzania (mean annual precipitation 825 mm) with maize as the main crop, Hatibu et al. (2003) compared a runoff area/basin area ratio of ≥1:1 in a microcatchment harvesting system and ≥10:1 in a macrocatchment systems with the local practice of flat cultivation as the control. They concluded that although the macrocatchment system provided the highest benefits for maize production, it was also associated with a potential erosion hazard related to the high flow rates of runoff.

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Table 4. Summary of some microcatchment and macrocatchment experiments carried out in arid and semiarid areas during the past 25 years

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Water harvest system Micro

Location

Mean annual precipitation (mm)

Soil texture class topsoil (USDA)

Crop/tree1

Measuring period (years)

Reference

Israel Israel India

300-500 91 700

Loam, clay Silt loam Loam

1980-1982 1982-1983 1980-1981

Agassi et al. (1985) Boers et al. (1986b) Kamra et al. (1986)

India Israel Jordan

360 209 150

1975-1981 1982-1984 1990-1992

Sharma (1986) Ben-Hur (1991) Abu-Irmaileh (1994)

India Pakistan Niger Jordan Sudan India Jordan China Jordan Iran Burkina Faso Ethiopia

300 180-305 570 150 150-400 264 – 263 150 420 800 450

Sandy loam Sandy clay loam Silty clay, Silty clay loam Loamy sand Silt Sand Silty clay loam Loam Sand Silty clay Sandy loam Silt Loam Sandy loam Loam

Wheat Pistacia vera Diplachna fusca, Brachiaria mutica – Wheat Natural vegetation

1990-1992 1990-1991 1985 1988-1989 1983-1990 1995-1996 1996-1998 1998 1995-1998 1983-1987 2000-2001 2000

Gupta (1994) Suleman et al. (1995) Tabor (1995) Oweis and Taimeh (1996) van Dijk (1997a) Ojasvi et al. (1999) Abu-Zreig et al. (2000) Li et al. (2000b) Abau-Zanat et al. (2004) Sepaskhah and Foolandmand (2004) Zougmoré et al. (2004) Abdelkdair and Schultz (2005)

Tunisia

240

Sandy loam

Azadirachta indica Grasses Millet and sorghum Almond – Jujube Olive Maize Atriplex spp. Grapes Sorghum Acacia spp. and Panicum maximun Olive

1998-2001

China China Ethiopia China Israel Burkina Faso

263 400 765 382 250-400 650

Silt loam Loam Sandy loam, loamy Clay loam Clay, loam –

Tamarix ramosissima Wheat Maize Potato Natural vegetation Millet, sorghum, rice, maize

2001-2004 2000-2003 2003-2004 2002-2003 2005 2004-2006

Fleskens et al. (2005), Schiettecatte et al. (2005) Li et al. (2005), Li et al. (2006) Xiao et al. (2007) Welderufael et al. (2008) Wang et al. (2008) Al-Seekh and Mohammad (2009) Barbier et al. (2009)

Table 4. (Continued) Water harvest system

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Macro

1

Soil texture class topsoil (USDA)

Crop/tree1

Syria China

Mean annual precipitation (mm) 210 250-350

Loam –

Saudi Arabia

270-338

Tunisia Chile

Location

Reference

Olive Sorghum and maize

Measuring period (years) 2002-2005 2005-2006

–

Juniperus procera

2006-2007

El Atta and Aref (2010)

240-300 317

Sand, clay Sandy loam

Olive Acacia saligna

2003 1996-2010

Previati et al. (2010) Salazar (2003), Salazar et al. (2006), Leiva (2005) and Casanova et al. (2010)

Botswana Jordan Sudan China

550 100-200 150-400 263

Sandy loam Silty clay loam Loam Sandy loam

1986-1989 1994-1996 1988-1990 1998-1999

Carter and Miller (1991) Abu-Awwad and Shatanawi (1997) van Dijk (1997b) Li et al. (2004)

Tunisia Pakistan

141 217

1995-1999 2006-2007

Nasri et al. (2004) Khan et al. (2009)

Tunisia

160-235

Sandy clay Silty clay, clay loam, silty clay loam, silt loam and loam Sand

Sorghum and maize – – Stipa purpurea, Artemisia scoparia, and Waldst. Et Kitag. (Virgate Sagebrush) Peas, olive and vineyard Wheat

1973-1984

Ouessar et al. (2009)

Chile Iran

100 290

Sandy loam Sandy loam

Rangeland, olives and cereals Rangeland -

1997-2005 2005-2006

Verbist, K. et al (2009) Ghazavi et al. (2010)

Experiments within crops mainly refer to runoff plot experiments.

Tubeileh et al. (2009) Wang et al. (2009)

Runoff Water Harvesting as a Strategy for Increasing Agricultural Production …

17

e. Effects of Soil Tillage Previati et al. (2010) concluded that tillage is one of the most important soil management practices in basin areas because it prevents a crust forming at the soil surface, favouring water infiltration. Welderufael et al. (2008) evaluated the potential benefits on maize yields of water harvesting with conventional tillage or no-tillage and found no statistical differences between the treatments. They attributed this to the rapid breakdown of clods in the conventional tillage treatment and rapid crust formation in both treatments.

f. Effects on Biometric and Physiological Plant Parameters A number of studies have found that water harvesting can have positive effects on biometric and physiological parameters of crops and trees. In an experiment in an olive plantation in Syria, Tubeileh et al. (2009) found that water harvesting improved stomatal conductance, leaf water content, leaf N content and growth of olive tree trunks. In Botswana, Carter and Miller (1991) found that water harvesting improved the plant available water content, increasing sorghum grain yield most during years of low or poorly distributed rainfall. In their study area, the probability of receiving runoff during three critical crop development stages exceeded 80%.

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g. Effects in Soil Fertility Case studies carried out to evaluate the effects of water harvesting on soil fertility status mainly relate this to the effect of solute and sediment transport in the runoff and to higher water volumes from runoff areas ‗washing‘ the soil profile. Niemeijer (1998) found that in a ‗teras‘ water harvesting system in Sudan, the organic carbon, nitrogen, phosphorus, potassium and magnesium contents were higher in the soils inside the basin areas than in upstream soils where no sedimentation occurred. Similarly, Ghazavi et al. (20101) reported that sediment depth, EC, Na, K, and Mg changed significantly in a basin area in Iran after implementation of a flood spreading macrocatchment water harvesting system. In studies on an arid Spanish island with some saline-sodic soils, Jiménez et al. (2004) found that compared with natural soils that did not receive runoff, soils with water harvesting had substantially lower EC and exchange sodium percentage values, an effect attributed to the change in the soil moisture regime caused by higher water supplies. In a study on an alkaline soil in India, Kamra et al. (1986) found that the pH value in the top 15 cm of soil in the basin area decreased from 10.6 to 9.0 after four years of runoff water harvesting. Van Dijk (1997a) reported that the bunds used in the ‗teras‘ water harvesting system in Sudan can also harvest sediment and organic material, such as animal droppings and crop residues from upslope locations, which may enhance the soil nutrient status of the soil in the basin areas. Gichangi et al. (2007) recommend combining water harvesting with integrated nutrient management, including farmyard and inorganic fertilisers, as an important strategy for increasing crop production in arid and semiarid regions.

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h. Economic Analysis In recent years there have been a number of economic analyses to evaluate the feasibility of runoff water harvesting projects in arid and semiarid areas. These studies usually attempt to determine the annual net benefit from water harvesting as the difference between the gross annual benefits from water harvesting and the annual cost of the capital investment in water harvesting, expressed as a benefit/cost ratio (Sharma et al., 2010). Economic analysis has to evaluate factors such as the size of the project (micro- or macro- water harvesting), the runoff area/basin area ratio, plant components (crops and/or trees), soil characteristics, management practices (fertiliser, tillage, etc.) and the life of the water harvesting structures. It will be particularly important in future economic analyses to consider climate factors, such as possible changes in rainfall amount and distribution in arid and semiarid regions as a result of predicted climatic change, which may affect the benefit/cost ratio. In India, several economic analyses have been carried out on water harvesting systems. For instance, Goel and Kumar (2005) evaluated different water harvesting alternatives in a mountainous region of India in terms of the size of the water harvesting structures and their expected life (25 and 40 years) and found benefit/cost ratios ranging from 0.41 to 1.33, by taking into account different crop return from maize and wheat. In a regional study in different districts of India, Sharma et al. (2010) carried out an economic analysis of water harvesting for different crop groups such as cereals, pulses and oilseeds and found that although water harvesting was economically viable, even at the regional scale, for all crop groups, it was more attractive for pulses and oilseed crops. Machiwal et al. (2004) evaluated the economics of low-cost water-harvesting structures using locally available materials and adapted to the socio-economic conditions in a semiarid region in India and concluded that dry stone masonry structures are very cost-effective for the region, with a benefit/cost ratio of 3.5:1. In Africa, an economic analysis by Hatibu et al. (2006) for a semiarid area of Tanzania considered the effect of rainfall variability during the year, with a season being defined as ‗below-average‘ when the rainfall amount was below the long-term mean and/or unevenly distributed within the season, and ‗above-average‘ when it was above the long-term mean and more evenly distributed. They found that water harvesting provided more benefits during above-average seasons compared with below-average. In Burkina Faso and Kenya, a benefit/cost analysis by Fox et al. (2005) indicated that there is a great need for support from government institutions through policies that enhance farmers‘ willingness to act with selfinterest, such as credit systems, and that provide extension services for farmers. A further conclusion was that implementation of water harvesting systems is only economically viable if combined with improved soil fertility management. The latter highlights the necessity of integrating runoff water harvesting with other management practices.

RUNOFF WATER HARVESTING MODELLING The mechanisms determining runoff water harvesting from hillslope areas in arid and semiarid zones are complex and depend on many factors, such as rainfall characteristics, soil surface conditions, stoniness and vegetation cover (Boers and Ben-Asher, 1982). In addition,

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 19 at the hillslope scale the spatial variability of surface characteristics and hence the hydrological response at the outlet of the catchment are difficult to predict, considering that the continuity of runoff pathways through the catchment depends on the interactions between a range of factors. The development of computer simulation models has provided tools to describe the hydrological and soil characteristic aspects of water harvesting. These have often been integrated with Geographic Information Systems (GIS) tools. A number of models are available to simulate runoff water harvesting processes, ranging from simple regression models to complex process-based models, including deterministic or stochastic approaches. A deterministic model has a set of initial inputs and boundary conditions with only one possible outcome of set of predictions, whereas a stochastic model contains random elements as a way of expressing uncertainty in initial inputs using a distribution of possible values and not a single deterministic value (Beven, 2008).

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a. Deterministic Modelling Approach Most of the models with a deterministic approach use soil, climate and crop parameters as inputs and usually produce as output the optimum ratio between runoff and basin areas. For instance, Boers et al. (1986b) developed a linear regression model combined with the transient one-dimensional finite difference water balance model ‗SWATRE‘ (Belmans et al., 1983) to simulate the complete water harvesting process in a microcatchment water system for a number of years. They used the model to evaluate the effect of different climatic conditions and soil physical properties on the optimum ratio between runoff area and basin area using equation (1) shown in a previous section. The SWATRE model is used to predict soil water content, assuming that groundwater is absent and there is only unsaturated flow. In this approach some data have to be measured e.g. daily rainfall, soil texture, while others can be estimated from measurements, e.g. unsaturated hydraulic conductivity can be estimated from soil texture. Using this model, Boers et al. (1986b) found that for the arid conditions of the Negev desert (annual rainfall around 200 mm), a microcatchment water system for pistachio trees would include a basin area of 40 m2 and a runoff area of between 40 and 80 m2. Similarly, Sepaskhah and Foolandmand (2004) designed a water balance model for a vineyard in Iran (annual rainfall around 420 mm) and found that for the local grape vine spacing of 3 x 3 m, the optimum runoff area should be 9 m2. More specific deterministic runoff models have been used to predict the water supply from runoff areas to basin areas, such as the Morin and Cluff (MC) runoff model (Welderufael et al., 2008). Other studies have used deterministic crop models to determine the effects of higher runoff water supply harvested from rainfall on crop yields. For instance, Stephens and Hess (1999) evaluated the PARCH model in a maize crop in an area of Kenya with mean annual rainfall of 400 mm, but ranging between 250 and 700 mm. They found that although runoff harvesting produced a significant yield increase in average years, there was no significant increase in dry and wet years. In a study in Zimbabwe, Mwenge Kahinda et al. (2007) used the Agricultural Production Simulator Model (APSIN) to simulate the effect of different combinations of water harvesting and organic/inorganic fertilisation on the yield of maize and concluded that water harvesting combined with inorganic fertiliser was the only treatment that closed the yield gap.

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A more complex deterministic model proposed by Young et al. (2002), the ParchedThirst model, combines crop, soil and runoff models. The combined model allows the most appropriate water harvesting technique for given conditions to be identified and provides information on transferring successful techniques to other areas. In addition, a sensitivity analysis performed in the model found that predicted runoff is very sensitive to saturated hydraulic conductivity as estimated using pedotransfer function models. Different modelling approaches have been used to fully describe the hydrological processes that occur in water harvesting systems. For example, Verbist et al. (2009) proposed an inverse modelling approach based on a combination of high spatial and temporal soil water content monitoring and the deterministic HYDRUS-2D model to evaluate the water balance of a simple water harvesting system in Chile, which included an infiltration trench in the basin area. Goswami (2007) developed a deterministic model to estimate the water balance in macrocatchment water harvesting systems considering the flow front in the inundation plain in the valleys (basin area), which was successfully evaluated in three catchments with area ranging from 500 to 1000 ha.

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b. Stochastic Modelling Approach Few stochastic approaches have been reported in water harvesting modelling, although Sanchez et al. (1995) noted that water harvesting modelling is best approached from a stochastic viewpoint, which offers a better platform for decision making since different hypothetical scenarios can be studied. They also recommended that stochastic approaches be used to study systems that are characterised by the occurrence of discrete random events, such as rainfall events in drylands. For instance, Tsubo et al. (2005) used a stochastic model to represent the rainfall intensity pattern in simulating long-term runoff and crop yield in water harvesting systems in South Africa. Sanchez et al. (1995) concluded that stochastic methods may also allow physical and financial risks in water harvesting systems to be quantified. On the other hand, it is possible to create a framework or hybrid model that can lump deterministic and stochastic models, e.g. Walker et al. (2005) developed a framework for rainfall-runoff-crop modelling for microcatchment water harvesting systems in South Africa using deterministic crop and runoff models combined with a stochastic rainfall intensity model. They found that the combination of deterministic and stochastic approaches resulted in a more flexible performance than the current empirical models of rainfall-runoff processes. Similarly, Tsubo and Walker (2007) used the same approach to demonstrate El Niño/La Niña effects on maize yield with a microcatchment water harvesting production system in a semiarid region of South Africa.

c. Geographic Information System Integration The growing interest in GIS tools has led to numerous modelling approaches in which this technique is included, mainly to identify potential areas for water harvesting projects. For instance, Sekar and Randhir (2007) developed a framework at watershed scale using spatial analysis tools of GIS to assess surface and groundwater harvesting potential, which they tested in a watershed in Massachusetts, USA. Their results showed that a spatially variable harvesting strategy can be used to minimise runoff losses and increase water supply.

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 21 Similarly, Ramakrishnan et al. (2009) utilised GIS in a study in India as a tool to store, analyse and integrate spatial and attribute information pertaining to runoff, slope, drainage, etc., but using the Soil Conservation Service Curve Number (SCS-CN) method to estimate runoff. These approaches can clearly improve the level of accuracy of locating areas for runoff water harvesting due to the ability of GIS to utilise spatial information in an integrative manner and to display this spatially through maps (de Winnaar et al., 2007). Recent evidence shows that the integration of hydrological models and GIS offers a potential synergy that appears to be the key feature for effective planning and design of runoff water harvesting systems at the catchment and regional scale. For example, Mwenge Kahinda et al. (2009) in South Africa developed a GIS-based runoff water harvesting decision support system (RHADESS) which identifies suitable areas for different types of runoff water harvesting and quantifies their impact in terms of changes in runoff. Ouessar et al. (2009) adapted and evaluated the GIS-based watershed model SWAT for simulating the water balance of a macrocatchment water harvesting system in Tunisia. Similarly, Andersson et al. (2009) used the SWAT model to estimate water availability for potential water harvesting in smallholder agriculture in South Africa. Attention has also focused on large-scale water harvesting planning by integrating GIS and remote sensing technologies to select suitable sites for construction of water harvesting structures. Many examples in the published literature demonstrate the capability of the GISremote sensing approach for runoff water harvesting planning over larger areas, for instance in Tanzania (Mbilinyi et al., 2007) and in a number of studies in India (Gupta et al., 1997; Kumar et al., 2008; Jasrotia et al., 2009; Singh et al., 2009). In addition, in a study of indigenous knowledge as a decision support tool for water harvesting planning in Tanzania, Mbilinyi et al. (2005) concluded that GIS may be an important tool for collecting and upscaling the utility of diverse indigenous knowledge in the decision-making process. One further way in which GIS may have great value is in transforming the results obtained from economic evaluations of the implementation of water harvesting systems into tools for decision-makers, e.g. by assessing the agro-ecological and socio-economic conditions under which investment in water harvesting measures could be a viable undertaking in arid and semiarid regions (Ouessar et al., 2004).

d. Uncertainty Estimation It is important to note that water harvesting modelling is demanding in terms of input data, which are often difficult to verify. Some estimations are needed when there is a lack of inputs and this incorporates uncertainties that are propagated in each step of the calculations. Thus, the number of unknown parameters and initial values is usually large enough with respect to the experimental data to ensure that calibration will find a set of values to provide a good fit. For instance, most of the runoff models require soil hydraulic properties, but direct measurements of these properties are time-consuming and therefore costly. As an alternative, pedotransfer functions have been proposed to indirectly estimate soil hydraulic properties from more easily measured and more readily available soil properties, such as particle size distribution, organic matter content and bulk density. Although these estimated parameters introduce additional uncertainties, most of the evaluations of water harvesting modelling in the literature lack an uncertainty analysis. Uncertainty analysis aims to measure the overall

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uncertainty associated with the model response as a result of uncertainties in measurements used as model inputs, boundary conditions and model structures (Beven, 2008). A few studies have included uncertainty estimation in the modelling building process, e.g. Andersson et al. (2009) used an uncertainty fitting algorithm (SUFI-2) for model calibration and uncertainty estimation. Uncertainty analysis should be an essential prerequisite for water harvesting model building, providing information on the pedigree of model predictions to users and decision-makers.

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AGROFORESTRY COMBINED WITH WATER HARVESTING In arid and semiarid zones, the components of agroforestry systems may compete rather than complementing each other as regards water use (Le Roux et al., 1995; Kho, 2000). Under such conditions, the expected yield advantage for annual crops in agroforestry systems will not occur, because it only arises when the water status of the soil profile remains high throughout the entire growing season (McIntyre et al., 1997). Furthermore, in such conditions nutrient contribution through fine root turnover is small, particularly in relation to that of aboveground biomass (Govindarajan et al., 1996). Based on experimental results, Lövenstein et al. (1991) suggest that agroforestry combined with runoff water harvesting in drylands can be a viable solution. Runoff water harvesting has been used for supplemental irrigation of agroforestry systems in rainfed areas, helping both to maintain and increase food production in these regions (Bhushan et al., 1992; Tabor, 1995; Li et al., 2000a). Droppelmann and Berliner (2003) noted that agroforestry combined with runoff water harvesting system is less affected by inter-annual rainfall variability than rainfed systems, and supports the natural regeneration of degraded rangeland. It is important to note that some combined agroforestry and water harvesting systems include the use of multipurpose trees, which may become an essential part of the livestock production system when the highly irregular rainfall in dryland areas causes the virtual disappearance of nutritious grasses during the dry season (Abdelkdair and Schultz, 2005). In this system, trees are planted in rows with intercropping, usually of cereals, in the basin area, as shown in Figure 7. When agroforestry is combined with water harvesting, differences in the rooting systems mean that soil water uptake by the trees and the annual crop has different spatial and temporal patterns (Morris et al., 1990; Lehmann et al., 1998a). In such cases, the tree roots do not explore the upper soil layers exhaustively but take up water from deeper layers, so the water from surface layers can be used by annual crops without affecting production of the perennial crop (Lövenstein et al., 1991).

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 23

Figure 7. Diagram of a system in which agroforestry is combined with water harvesting.

Furthermore, the tree root systems can react to the change from dry to wet seasons and compensate by growing deeper during drought periods (Lehmann et al., 1998b). Thus, the integration of deep-rooting trees with a cultivated crop allows a higher efficiency of nutrient use (Hartemink et al., 1996; Lehmann et al., 1999).

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CASE STUDY: AGROFORESTRY COMBINED WITH MICROCATCHMENT WATER HARVESTING IN THE SEMIARID ZONE OF CHILE A field study was carried out in a rainfed area of central Chile, 20 km from Santiago (33°28´S; 70°50´W, altitude 470 m a.s.l) between 1996 and 2000. The field experiment was located at the Germán Greve Silva Experimental Station, part of the Faculty of Agronomic Sciences at the University of Chile (Figure 8). A detailed description of the area, measurements and management practices in the field experiment is given by Salazar (2003), Leiva (2005) Salazar et al. (2006), and Casanova et al. (2010). The soil at the site is a sandy loam up to 100 cm depth, resting on a colluvial substratum (gravel and stones) with a sandy clay loam matrix. The gravel content in the 0-40 cm layer ranges from 3 to 7%. The soil is located in a piedmont position on a slightly inclined plain (slope 7-10%) and has a colluvial origin but with alluvial influence (Luzio et al., 2010). It belongs to the Cuesta Barriga Soil Series and is classified as a Typic Haploxeroll with a thermic soil temperature regime and xeric soil moisture regime (CIREN, 1996). The soil is well drained, with moderately slow internal drainage and rapid external drainage. The climate in the study area is classified according to the Köppen-Geiger system as temperate with dry and warm summer seasons, corresponding to Csb (Peel et al., 2007). The site has a mean annual air temperature of 14.2 °C and mean annual precipitation of 317 mm (using 1960-2003 data from a meteorological station at the Germán Greve Silva Experimental Station), and is characterised by a strong seasonal rainfall distribution, with 75% falling in the winter months. For instance, between 1996 and 2000, the rainfall distribution was irregular

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between years, ranging from 80 to 671 mm year-1, with the highest monthly amount falling during June (see Figure 9).

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Figure 8. Field experiment at the Germán Greve Silva Experimental Station, Chile.

The objective of the study was to evaluate the influence of combined agroforestry and water harvesting on some soil fertility parameters, such as soil organic matter (SOM), total nitrogen (NT), total phosphorus (PT) and total potassium (KT) contents, which were measured at regular soil sampling depths of 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm. Fifteen plots were installed in a randomised block design (Blocks 1-3). The treatments were two crop management systems, two water management systems and a control, with three replicates per treatment. The plot size was 15 m x 11 m. The microcatchment water harvesting plots consisted of a runoff catchment area of 10 m x 11 m and a growing area of 5 m x 11 m. This runoff area/basin area ratio (3:1) was calculated considering previous runoff measurements made by Joel et al. (2002) in the same area. The crop management systems were agroforestry and woody perennials. Acacia saligna (Labill.) H. Wendl was used as the woody perennial component. All plots were covered by native Mediterranean annual prairie. The annual crop was oats (Avena sativa L.), which was only sown in the first year after ploughing to a depth of 10 cm. Therefore, after the second year there were three crop and water management systems: annual prairie (P), woody perennial and annual prairie (A and W), and woody perennial and annual prairie with water harvesting (AR and WR) (Table 5).

Figure 9. Rainfall distribution (mm month-1) between 1996 and 2000 in central Chile. Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 25 Table 5. Description of treatments (P: annual prairie; A: agroforestry; AR: agroforestry with water harvesting; W: woody perennial; WR: woody perennial with water harvesting) used in the field experiment in central Chile Treatment P A AR W WR

Control Agroforestry Agroforestry with water harvesting Woody perennial Woody perennial with water harvesting

Species 1996 Annual prairie Acacia, oats and annual prairie Acacia, oats and annual prairie

1997-2010 Annual prairie Acacia and annual prairie Acacia and annual prairie

Acacia and annual prairie Acacia and annual prairie

Acacia and annual prairie Acacia and annual prairie

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In addition, to determine the plant development of Acacia saligna trees, the trunk basal perimeter (BP) was measured at 10 cm above the ground line. Biomass production of the Mediterranean annual prairie was determined according to the point quadrat method.

Figure 10. a) Soil organic matter content (SOM) and b) total nitrogen (NT) content in different soil layers in 2008 for the treatments control (P), agroforestry (A), agroforestry with water harvesting (AR), woody perennial (W) and woody perennial with water harvesting (WR).

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In the treatment control (P), there was a slight trend of decreasing soil organic matter (SOM) over time, which may indicate a negative SOM balance in the degraded Mediterranean annual prairie system with low C inputs. Unlike treatment P, the treatments with Acacia saligna trees (A, AR, W and WR) increased the SOM stocks, probably due to higher SOM inputs from the litter and root turnover. In 2008, the highest amounts of SOM content were found in the 0-10 cm layer (Figure 10a). In this layer, agroforestry with water harvesting (AR) and agroforestry treatment (A) showed the highest SOM contents, with 6.2% and 7.6%, respectively. In these treatments the tillage may have improved the infiltration capacity of the soil surface, augmenting the soil water supply to the processes of litter and root turnover. The treatment woody perennial with water harvesting (WR) gave the most homogeneous distribution of SOM in the soil profile. On the other hand, the control (P) gave the lowest SOM content in all layers, with values ranging from 4.3% in the 0-10 cm layer to 1.5% at 30-40 cm depth (Figure 10a). On average, the treatments with water harvesting (AR and WR) had the highest SOM contents, which suggests that this practice had positive effects in improving the water content in the soil and thus stimulating biomass production of Acacia saligna and its decomposition and favouring the process of root turnover. This higher biomass production of Acacia saligna in AR and WR was reflected in these treatments in the highest values of trunk basal perimeter (BP), a biometric parameter directly related to high biomass production of Acacia saligna in some studies (Steward and Salazar, 1992; Lövenstein and Berliner, 1993; Droppelmann and Berliner, 2000). Comparing N stocks measured in 2000 and 2008, there was a trend of increasing N content in the treatments with Acacia saligna trees (A, AR, W and WR), which had higher N stocks than the P treatment, probably due to higher N inputs from N fixation. The highest average N stocks were found in the treatments with water harvesting (AR and WR), which suggests that this augmentation of N content might also be related to positive effects of higher water content on root litter input. For instance, in 2008 the AR and WR treatments had the highest total N content in the 0-10 cm layer, 0.30% and 0.34% respectively, whereas the P treatment had the lowest total N content, 0.20% (Figure 10b). Treatments with water harvesting (AR and WR) showed a lack of significant differences compared with the other treatments (P, A and W) in terms of pH and total P and total K levels in 2008 (Figure 11). This might be due to the fact that this study was of short duration and therefore its potential contributions towards improving soil properties may not have been fully realised. For example, Nair et al. (1995) noted that in agroforestry, the potential long-term benefits of soil improvement are often not manifested in the short-term. Despite this, agroforestry combined with water harvesting showed some positive effects, with the highest accumulation of both SOM and NT content as a result of increased litter and root turnover (Figure 11).

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 27

Figure 11. a) Total phosphorus (PT) content and b) soil reaction (pH) in different soil layers in 2008 for the treatments control (P), agroforestry (A), agroforestry with water harvesting (AR), woody perennial (W) and woody perennial with water harvesting (WR).

FUTURE CHALLENGES IN RUNOFF WATER HARVESTING A wealth of recent information on future trends in climate change has been obtained from modelling studies, which usually predict a decline in regional precipitation and an increase in temperature, leading to higher crop water stresses in arid and semiarid regions (World Water Council, 2009). Thus runoff water harvesting has been proposed as a means to mitigate the effects of climate change in arid and semiarid regions. For instance, Rost et al. (2009) quantified the water limitations in global crop production and the potential of runoff water harvesting and reduced soil evaporation to improve crop growth under projected climate change scenarios. They determined that a combination of runoff water harvesting and techniques to reduce soil evaporation could increase global crop production by almost 20%.

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However, a number of problems with water harvesting implementation in arid and semiarid regions remain unsolved and these must be tackled to transform runoff water harvesting into a viable option to mitigate the uncertain future water availability in drylands. One of the most important future challenges will be to increase the adoption of runoff water harvesting in many arid and semiarid regions. The factors behind the current lack of implementation of water harvesting techniques in these areas first need to be identified. As noted by Li et al. (2000a), there can be constraints caused by technological, agrohydrological, ecological, social, cultural, economic and political factors. For instance, He et al. (2007) applied a logistic model to identify factors, other than pure agronomic characteristics, affecting the implementation of water harvesting in a semiarid area in China and found that e.g. educational background and contact with extension workers explained the decision to adopt water harvesting. Once the underlying factors have been identified, the next challenges will be to find ways of embedding innovative water harvesting systems by adapting them to the site-specific biophysical and socio-economic context of the farmers, and to involve all stakeholders in planning, design and implementation of water harvesting systems (Rockström, 2000; Oweis and Hachum, 2009). Rockström and Falkenmark (2000) noted that is also necessary to ensure strong research-farming-extension technical communication, which may help during the design and implementation of water harvesting systems. This is especially important in areas where small-holder farming is dominant, which usually lack government and institutional technology transfer. Moreover, Hatibu et al. (2002) concluded that family labour availability and access to farm power are important characteristics of farms influencing adoption of runoff water harvesting techniques. The future water availability projections for dryland due to climate change are not very optimistic. Huge efforts will be needed to provide available water to sustain the increasing food demand in arid and semiarid regions with rainfed agricultural systems. Thus it is possible that in the future, governments and public institutions will require information from watershed or regional scale studies as operational units for planning national water management programmes to increase water availability for crop production in these areas (Vohland and Barry, 2009; Wani et al., 2009). However, most of the water harvesting studies carried out in arid and semiarid regions during the past 25 years have mainly focused on the field scale, using microcatchment water harvesting systems. This is probably because water harvesting remains practicable only on a small scale (with catchments of about 100 m2 or less), as is most common in traditional or isolated settings. In addition, Hutchinson et al. (2010) point out that over the past 50 years, large-scale industrial water harvesting systems have not proven economically viable, primarily due to the cost of labour. Therefore, we suggest two alternatives: 1) Increase the number of water harvesting macrocatchment projects connected to regional governmental water programmes, and 2) upscale the current microcatchment water harvesting systems to larger scales. The latter can be achieved with the help of hydrological models to evaluate the possible impacts of runoff water harvesting at larger scales. For example, Glendenning (2009) developed a conceptual water balance model to evaluate the effects of microcatchment water harvesting structures at catchment scale in India. However, it is important to consider that an increase in the number of macrocatchment water harvesting projects may also increase the competition and conflicts in sharing harvested runoff water among a large number of stakeholders at regional scale (Hatibu et al., 2003). This will be a new challenge, especially in areas where farmers lack any concept of communal organisation beyond the extended household level (Hogg, 1988). This

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 29 constraint may have to be overcome by new policies, legislation and institutional order to manage runoff water harvesting systems and thus ensure the successful implementation of these systems (Ngigi, 2003). Finally, it is important to note that successful implementation of water harvesting systems will also rely on their integration with other crop management practices, such as tillage, nutrient and crop residue management, crop rotations, application of amendment or sealing in runoff areas, etc. These have been stressed in other reviews as critical points to be resolved in arid and semiarid zones (Kronen, 1994; Mupangwa et al., 2006; Tenywa and Bekunda, 2008; Vohland and Barry, 2009). There is evidence to suggest that unless these management practices are included, e.g. to reduce infiltration in runoff areas and reduce evaporation and increase water storage in basin areas, the potential of water harvesting to mitigate adverse climate change effects on drylands will not be fully realised.

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CONCLUSION Research carried out over the past 25 years clearly demonstrates that properly designed runoff water harvesting techniques can be a real alternative to increase agricultural production on hillslope areas in arid and semiarid zones. Research into water harvesting during this period can be roughly grouped into experimental and modelling approaches. Although experimental field studies have attempted to link water harvesting with soil management practices such as tillage, nutrient and crop residue management, crop rotation, etc., the integration of soil and water management practices is still a critical point that has to be overcome in future research in arid and semiarid zones. Indeed, there is evidence to suggest that unless soil management practices are included, the potential of water harvesting to mitigate adverse climate change effects on drylands will not be fully realised. To date, modelling has tended to focus on identifying areas with potential for use in runoff water harvesting, usually with the help of Geographical Information Systems (GIS). One of the main objectives for future modelling studies will be to assess the impact of future climate change on the efficiency of runoff water harvesting techniques. Well calibrated and validated models may help evaluate how possible changes, e.g. in distribution and amount of rainfall in arid and semiarid zones, may be ameliorated by modifying the design and management of the current runoff water harvesting systems. Moreover, the widespread availability of digital geographical data opens up new opportunities for using models in water harvesting planning at regional scale. Thus the integration of simulation models and GIS offers a potential synergy that appears to be key for effective development of water harvesting as a measure to mitigate future increasing water scarcity in arid and semiarid regions. However, most of the existing modelling studies on water harvesting lack an uncertainty analysis, which should be an essential prerequisite for model building in future modelling approaches. In the example presented in this chapter, the use of runoff water for supplemental irrigation of agroforestry systems in central Chile proved to be beneficial for soil properties such as organic matter content and total nitrogen content.

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Runoff Water Harvesting as a Strategy for Increasing Agricultural Production … 37 Salazar, O., Casanova, M., Benavides, C. et al. (2006). Propiedades químicas de un suelo bajo agroforestería y cosecha de agua en el secano interior de la zona central de Chile. TERRA Latinoamericana: 24 (4), 471-476. (in Spanish with English summary). Sánchez, C.I., Lopes, V.L., Slack, D.C. et al. (1995). Assessing risk for water harvesting systems in arid environments. Journal of Soil and Water Conservation: 50 (5), 446-449. Schiettecatte, W., Ouessar, Gabriels, D. et al. (2005). Impact of water harvesting techniques on soil and water conservation: a case study on a micro catchment in southeastern Tunisia. Journal of Arid Environments: 61 (2), 297-313. Sekar, I. and Randhir, T.O. (2007). Spatial assessment of conjunctive water harvesting potential in watershed systems. Journal of Hydrology: 334 (1-2), 39-52. Sepaskhah, A.R. and Foolandmand, H.R. (2004). A computer model for design of microcatchment water harvesting systems for rain-fed vineyard. Agricultural Water Management: 64 (3), 213-232. Sharma, K.D. (1986). Runoff behaviour of water harvesting microcatchments. Agricultural Water Management: 11 (2), 137-144. Sharma, B.R., Raob, K.V., Vittal, K.P.R. et al. (2010). Estimating the potential of rainfed agriculture in India: Prospects for water productivity improvements. Agricultural Water Management: 97 (1), 23-30. Singh, J.P., Singh, D. and Litoria, P.K. (2009). Selection of suitable sites for water harvesting structures in Soankhad watershed, Punjab using remote sensing and geographical information system. Journal of the Indian Society of Remote Sensing: 37 (1), 21–35. Stephens, W. and Hess, T.M. (1999). Modelling the benefits of soil water conservation using the PARCH model – case study from a semi-arid region of Kenya. Journal of Arid Environments: 41 (3), 335-344. Stewart, J.L. and Salazar, R. (1992). A review of measurement options for multipurpose trees. Agroforestry Systems: 19 (2), 173-183. Suleman, S., Wood, M.K., Shah, B.H. et al. (1995). Development of a rainwater harvesting system for increasing soil moisture in arid rangelands of Pakistan. Journal of Arid Environments: 31 (4), 471-481. Tabor, J.A. (1995). Improving crop yields in the Sahel by means of water-harvesting. Journal of Arid Environments: 30 (1), 83-106. Tauer, W., Prinz, D. andVögtle, T. (1991). The potential of runoff-farming in the Sahel region : developing a methodology to identify suitable areas. Water Resources Management: 5 (3-4), 281-287. Tenywa, M.M. and Bekunda, M. (2008). Managing soils in Sub-Saharan Africa: challenges and opportunities for soil and water conservation. Journal of Soil and Water Conservation: 64 (1), 44A-48A. Tsubo, M., Walker, S. and Hensley, M. (2005). Quantifying risk for water harvesting under semi-arid conditions. Part I. Rainfall intensity generation. Agricultural Water Management: 76 (2), 77-93. Tsubo, M. and Walker, S. (2007). An assessment of productivity of maize grown under water harvesting system in a semi-arid region with special reference to ENSO. Journal of Arid Environments: 71 (), 299-311. Tubeileh, A., Bruggeman, A. and Turkelboom, F. (2009). Effect of water harvesting on growth of young olive trees in degraded Syrian dryland. Environment, Development and Sustainability: 11 (5), 1073-1090.

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van Dijk, J.A. (1997a). Indigenous soil and water conservation by teras in eastern Sudan. Land Degradation and Development: 8 (1), 17-26. van Dijk, J.A. (1997b). Simple methods for soil moisture assessment in water harvesting projects. Journal of Arid Environments: 35 (), 387-394. van Dijk, J.A. and Ahmed, M.H. (1993). Opportunities for expanding water harvesting in Sub-Saharan Africa: the case of the Teras of Kassala: Volume 40. International Institute for Environment and Development, Gatekeeper Series. Verbist, K., Cornelis, W.M., Gabriels, D., et al. (2009). Using an inverse modelling approach to evaluate the water retention in a simple water harvesting technique. Hydrology and Earth System Sciences: 13 (10), 1979-1992. Vittal, K.P.R., Vijayalakshmi, K., Rao, U.M.B. (1988). Interception and storage of surface runoff in ponds in small agricultural watersheds, Andhra Pradesh, India. Irrigation Sciences: 9 (1), 69-75. Vohland, K. and Barry, B. (2009). A review of in situ rainwater harvesting (RWH) practices modifying landscape functions in African drylands. Agriculture, Ecosystems and Environment: 131 (3-4), 119-127. Walker, S., Tsubo, M. and Hensley, M. (2005). Quantifying risk for water harvesting under semi-arid conditions Part II. Crop yield simulation. Agricultural Water Management: 76 (2), 94-107. Wang, Q., Zhang, E., Li, F. et al. (2008). Runoff efficiency and the technique of microwater harvesting with ridges and furrows, for potato production in semi-arid areas. Water Resource Management: 22 (10), 1431-1443. Wang, Y., Xie, Z., Malhi, S.S. et al. (2009). Effects of rainfall harvesting and mulching technologies on water use efficiency and crop yield in the semi-arid Loess Plateau, China. Agricultural Water Management: 96 (3), 374-382. Wani, S.P., Sreedevi, T.K., Rockström, J. et al. (2009). Rainfed agriculture – Past trends and future prospects, in: Wani, S.P, Rockström, J. and Oweis, T. (Eds.), Rainfed Agriculture: unlocking the potential, CAB international, pp. 1–35. Welderufael. W.A., Le Roux. P.A.L., Hensley, M. (2008). Quantifying rainfall–runoff relationships on the Dera Calcic Fluvic Regosol ecotope in Ethiopia. Agricultural Water Management: 95 (11), 1223-1232. World Water Council. (2009). Vulnerability of arid and semiarid regions to climatic change – Impacts and adaptive strategies: Volume. 9. Perspectives on water and climate change adaptation Series. Xiao, G., Zhang, Q, Xiong, Y., et al. (2007). Integrating rainwater harvesting with supplemental irrigation into rain-fed spring wheat farming. Soil and Tillage Research: 93 (2), 429-437. Young, M.D.B., Gowing, J.W., Wyseure, G.C.L. et al. (2002). Parched-Thirst: development and validation of a process-based model of rainwater harvesting. Agricultural Water Management: 55 (2), 121-140. Yuen, E., Anda, M., Mathew, K. et al. (2001). Water harvesting techniques for small communities in arid areas. Water Science and Technology: 44 (6), 189-194.

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Zhao, X.N. Wu, P.T., Feng, H. et al. (2009). Towards Development of Eco-Agriculture of Rainwater-Harvesting for Supplemental Irrigation in the Semi-Arid Loess Plateau of China. Journal of Agronomy and Crop Science: 195 (6), 339-407. Zougmoré, R., Mando, A. and Stroosnijder, L. (2004). Effect of soil and water conservation and nutrient management on the soil–plant water balance in semi-arid Burkina Faso. Agricultural Water Management: 65 (2), 103-120.

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In: Water Recycling and Water Management Editor: Daniel M. Carrey

ISBN: 978-1-61761-305-0 © 2011 Nova Science Publishers, Inc.

Chapter 2

WATER MANAGEMENT IN DROUGHT-PRONE AREA M. H. Ali Agricultural Engg. Division, Bangladesh Institute of Nuclear Agriculture BAU Campus, Mymensingh 2202, Bangladesh

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1. BACKGROUND Water deficit in an area may arise from many factors such as low rainfall, uneven distribution, high losses due to evaporation and runoff, and absence of source of irrigation water. Seasonally dry tropics are spread over parts of 49 countries covering an area of over 20 million km2 in five continents and support more than 600 million people mostly living at subsistence level on small farms and practicing rainfed agriculture to meet their food and fodder requirements. Most of Indian subcontinent falls under the semi-arid tropics where 74% of the arable land is rainfed and contributes only 45% to the national food production. Improved water management will determine the prospects of increasing crop production in such seasonally dry areas, but the management techniques may vary from region to region depending on the amount and distribution of rainfall, nature and properties of soil, crop grown and socio-economic conditions.

2. THE CONCEPTS, TYPES AND INDICES OF DROUGHT Concept of Drought An understanding of the drought conditions in time and space is fundamental to a wide range of water management problems. Drought occurs in virtually all climatic zones. However, its characteristics vary significantly from one region to anther. Drought is a normal, recurrent feature of climate (although many people erroneously consider it a rare and random



Email: [email protected], [email protected]

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event). Drought is a temporary aberration; it differs from aridity, which is restricted to low rainfall regions and is a permanent feature of climate.

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Types of Drought Drought has been defined under different perspectives: hydrological, meteorological, agricultural, socio-economic, etc. Hydrological drought refers to deficiencies in surface and subsurface water supplies. It is measured as stream-flow and as lake, reservoir, and groundwater levels. There is a time lag between lack of rain and less water in streams, rivers, lakes, and reservoirs, so hydrological measurements are not the instantaneous indicators of drought. When precipitation is reduced or deficient over an extended period of time, this shortage will be reflected in declining surface and subsurface water levels. Meteorological drought is usually an expression of precipitation‘s departure from normal (long-term average) over some period of time. This definition is usually region-specific, and presumably based on a thorough understanding of regional climatology. Socioeconomic drought occurs when physical water shortage starts to affect people individually and collectively. Agricultural drought occurs when there is not enough soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought happens after meteorological drought but before hydrological drought. Agriculture is usually the first economic sector to be affected by drought. Drought risk is based on a combination of the frequency, severity, and spatial extent of drought (the physical nature of drought) and the degree to which a population or activity is vulnerable to the effects of drought. The degree of a region‘s vulnerability depends on the environmental and social characteristics of the region and is measured by their ability to anticipate, cope with, resist, and recover from drought. Drought can result in many direct and indirect impacts. Some of these may be more important than others in terms of individual‘s values and interests. Addressing the most significant impacts first will help target limited resources and hopefully have a larger effect in reducing drought impacts and vulnerabilities. One important aspect of reducing vulnerability is to understand the impacts of drought. Each drought produces a unique set of impacts, depending not only on the drought‘s severity, duration, and spatial extent but also on everchanging social conditions. These impacts are often symptoms of other underlying problems (vulnerabilities). Understanding trends in drought occurrence and impacts over time is important for projecting potential future impacts and understanding our changing vulnerabilities. With a good understanding of drought impacts that have affected or could affect our livelihood or activity, the most significant impacts can then be identified for further review by conducting a drought impact assessment.

Indices of Drought The quantity and distribution of rainfall during a cropping season accounts for a large proportion of the year-to-year yield variation of summer annual crops. Drought may be avoided by matching crop phenology with periods during the cropping season when water

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supply is likely to be more abundant. This approach has been an effective tool for crop grown in monsoonal climates where they are sown near the beginning of the wet season and mature before the dry season. Various kinds of drought indices are available in practice. There are several indices that measure how much precipitation for a given period of time has deviated from historically established norms. Although none of the major indices is inherently superior to the rest in all circumstances, some indices are better suited than others for certain uses. For example, the Palmer Drought Severity Index has been widely used by the U.S. Department of Agriculture to determine when to grant emergency drought assistance, but the Palmer is better when working with large areas of uniform topography. The National Drought Mitigation Center of USA is using a newer index, the Standardized Precipitation Index, to monitor moisture supply conditions. Distinguishing traits of this index are that it identifies emerging droughts months sooner than the Palmer Index and that it is computed on various time scales. It is useful to consult one or more indices before making a decision. An introduction to each of the major drought indices in use are given below.

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Percent of Normal The percent of normal precipitation is one of the simplest measurements of rainfall for a location. Analyses using the percent of normal are very effective when used for a single region or a single season. Percent of normal is also easily misunderstood and gives different indications of conditions, depending on the location and season. It is calculated by dividing actual precipitation by normal precipitation—typically considered to be a 30-year mean—and multiplying by 100%. This can be calculated for a variety of time scales. Usually these time scales range from a single month to a group of months representing a particular season, to an annual or water year. Normal precipitation for a specific location is considered to be 100%.

Standardized Precipitation Index (SPI) The SPI is an index based on the probability of precipitation for any time scale (Hayes et al., 1999). The SPI can be computed for different time scales, can provide early warning of drought and help assess drought severity, and is less complex than the Palmer. SPI value 2.0+ 1.5 to 1.99 1.0 to 1.49 -.99 to .99 -1.0 to -1.49 -1.5 to -1.99 -2 and less

Characteristic extremely wet very wet moderately wet near normal moderately dry severely dry extremely dry

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One of the disadvantages of using the percent of normal precipitation is that the mean, or average precipitation is often not the same as the median precipitation, which is the value exceeded by 50% of the precipitation occurrences in a long-term climate record. The reason for this is that precipitation on monthly or seasonal scales does not have a normal distribution. Use of the percent of normal comparison implies a normal distribution where the mean and median are considered to be the same.

Palmer Drought Severity Index (PDSI) Palmer developed an index to measure the departure of the moisture supply (Palmer, 1965), which is then called as Palmer Drought Severity Index (PDSI). Palmer based his index on the supply-and-demand concept of the water balance equation to evaluate drought severity, taking into account more than just the precipitation deficit at specific locations, which is normalized for the departure from climatological norms. From the inputs, all the basic terms of the water balance equation can be determined, including evapotranspiration, soil recharge, runoff, and moisture loss from the surface layer. Human impacts on the water balance, such as irrigation, are not considered. The objective of PDSI was to provide measurements of moisture conditions that were standardized so that comparisons using the index could be made between locations and between months (Palmer 1965).When conditions change from dry to normal or wet (for example), the drought measured by the PDSI ends without taking into account stream flow, lake and reservoir levels, and other longer-term hydrologic impacts.

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Crop Moisture Index (CMI) The Crop Moisture Index (CMI) uses a meteorological approach to monitor week-toweek crop conditions. It was developed by Palmer (1968) from procedures within the calculation of the PDSI. Whereas the PDSI monitors long-term meteorological wet and dry spells, the CMI was designed to evaluate short-term moisture conditions across major cropproducing regions. It is based on the mean temperature and total precipitation for each week within a climate division, as well as the CMI value from the previous week. The CMI responds rapidly to changing conditions, and it is weighted by location and time.

3. WATER MANAGEMENT: APPROACHES AND STRATEGIES Basic Approaches The basic approach to planning of any resource is to determine:   

the needs the resources, and ways to develop the resources to meet needs, on the basis of the technological, financial and human resources, which are available.

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Water resources should be managed in the context of a national water strategy that reflects the nation‘s social, economic, and environmental objectives and is based on an assessment of the water resources. The assessment would include a realistic forecast of the demand for water, based on projected population growth and economic development, and a consideration of options for managing demand and supply, taking into account existing investment and likely to occur in the private sector. There are two major approaches for improving and sustaining crop productivity in a water-short (drought-prone) environment:  

Modifying the environment to suit the plant, and Modifying the plants to suit the environment.

The first approach resembles to ‗water supply management‘ and the second approach resembles to ‗water demand management‘.

Estimation of Demand and Supply of Water For proper planning and management of any resource, knowledge of demand and supply is pre-requisite.

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Demand Estimation The evaluation of future effective water consumption is more difficult as it implies knowledge of interventions by man. For example, a country may change its fundamental economic options: agriculture vs industrialization following a change in government. New technological development may promote the conservation of water, such as inexpensive methods for surface water treatment in tropical countries, or by changing water needs through the use of drip irrigation. An evaluation of future demand should be based on the results of a recent comprehensive survey of water users. Forecasts of future uses of water resources on the basis of various ‗scenarios‘ for exploitation should also be undertaken. These can be achieved by means of mathematical models. Demands for water in a region can be classified into following sectors: i. ii. iii. iv.

demand for domestic, industrial and commercial uses irrigation demand evaporative demand for fisheries, forestry and environment, and in-stream demand

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Management Strategies of Water Resources Management strategies of water can be broadly categorized into two classes: a) Demand management, and b) Supply management.

Demand Side Management Demand management options refer the actions that influence the use of water after the entry point. Demand side management is commonly implemented together with a water conservation program. Water conservation is generally accepted to mean ―the minimization of loss or waste, the preservation, care and protection of water resources and the efficient and effective use of water‖. Demand side management involves a broad range of measures that aim to increase the efficiency of water use. Demand management may be defined as the adaptation and implementation of a strategy by a water institution to influence the water demand and usage in order to meet any of the following objectives: economic efficiency, social development, social equity, environmental protection, sustainability of water supply and services, and political acceptability.

Different Approaches of Demand Management

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The measures for demand management include:          

conservation-oriented rate structures (e.g. metering and prices) water ordinance reduction of conveyance loss water conservation measures cultivating drought tolerant species water savings irrigation practices in agriculture water reuse pressure management in irrigation system water audit public awareness campaigns, etc.

Demand side management may be pursued for various reasons, including postponding construction of new water or wastewater infrastructure, decreasing operation and maintenance costs, and environmental impacts of increasing withdrawals. Demand managed strategies applied around the world today can be grouped into four categories: i.

technological

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ii. economic iii. institutional, and iv. behavioral In the agricultural water sector, techniques include:      

reduction / removing of pricing subsidies selecting crops with high yields per unit water consumed introducing efficient irrigation devices/ methods land leveling water-wise tilling/field preparation efficient/water-saving irrigation scheduling

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Description of Different Approaches Metering and Pricing Metering and pricing are generally considered to be the building blocks of a demand side management. Metering may be more widespread in the industrial and institutional sectors. These categories may have fewer but larger water users, than in the residential and commercial sectors. In the short-term, the introduction of metering can impact for water. However, ultimately metering must be used in combination with appropriate pricing structures, to provide an incentive for customers to reduce water use. Along with various rate structure, the increasing block-rate pricing structure (also termed as tiered water prices) may be an explicitly water conserving rate structure: when water use reaches a certain threshold (the boundary between ―blocks‖), the price per unit goes up. Tiered pricing provides an incentive for the farmers to choose efficient combinations of irrigation methods and management levels. However, to remain effective, such a structure must be keyed to inflation so that the amount charged for water is consistent with the real cost of providing the service. Declining block rate often are thought to encourage higher levels of water use, as the price per unit of water used goes down in steps or blocks, the amount used increases. Water Ordinance (by-Law) State or municipal ordinance may promote water conservation and efficient use of water. Water rate ordinance simply authorize various rate structures in place. Other ordinances (i.e. plumbing fixture, mandatory fixture retrofit, restrictions on specific users, and others) may also be employed. Regional municipalities or agricultural area may have lawn watering ordinances in place, compare to others. Operational and Maintenance Measures Directing Reduce Water Loss A wide range of operational and maintenance (O and M) measures directed at reducing water losses and consumption may be employed. Several of these measures, including leak detection, repair of water distribution lines, may be part of normal infrastructure maintenance. Other measures, such as installing new meters on unmetered accounts, reservoir renovation, water pressure reduction, etc. may be aimed at reducing water loss.

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Water-Saving Irrigation Scheduling Alternate Furrow Irrigation Experimental results suggest that water use can be decreased by almost 33 % by irrigating alternate furrows instead of every furrow. Most of the water savings, however occur on the lower part of the field. Alternate Wetting and Drying of Rice Field In rice cultivation, instead of continuous ponding the field to a certain depth, irrigating after 3 to 5 days of disappearance of ponded water saves about 30 ~35 % water without reduction in yield.

Soil Drying During Ripening of Crop In most crops (especially in cereals), we are interested to produce higher grain yield, but not the straw yield. Soil drying during the grain filling period of rice and wheat enhance early senescence. The grain filling period may be shortened under such a condition, but a faster rate of grain-filling and enhanced mobilization of stored carbohydrate to grain minimizes the effect on yield. Thus, water demand can be minimized without reduction in yield. In some cases, it increases yield.

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Deficit Irrigation Omitting irrigation at less sensitive growth stages of plants (with respect to water deficit) minimizes irrigation requirement without significant yield reduction. Adopting Efficient Irrigation Method On-farm water use efficiency can be improved by moving to a more efficient irrigation system. Sprinkler and drip irrigation can save non-effective water loss. Minimization of water loss during land preparation in wet-land culture of rice (substitution by dry-seeded rice) leads to lower total water requirement. Water Loss Minimization Water loss in the conveyance system can be reduced through canal lining. A range of materials are available for that purpose. On-farm water loss (seepage through boarders of the plot) can be reduced through minimizing holes and proper maintenance of the boarders with sufficient height. Thus, actual need of irrigation water would be reduced. Public Awareness Approaches Public awareness and education have been identified as key aspects of any demand side management plan in many places around the world. The most frequently used public awareness approaches directed to encourage water conservation are print media (brochures), information packages, media information, public lectures and meetings, working with local school, low water use landscape demonstration, etc. Demonstration of real cost savings to consumers may be an effective means to reduce water loss.

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Other Measures

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These include working with large water users to conserve water, water conservation plans or strategies, water audit of homes or businesses, and working with other organizations or groups to promote water conservation. The appropriateness of different types of demand side measures may be a function of factors related to municipality type (e.g. village or towns), financial and organizational capacity, type of housing stock, etc. Any combination of the measures or awareness campaign (suitable for the site concern) may be implemented. The effectiveness of some measures is known to depend on the presence of others. For instance, while metering can lead to a shortterm 30 to 50 % reduction in demand, water consumption can return to previous levels if metering is not combined with pricing rate structures that tie the cost to the amount used. The long-term effectiveness of some measures can declined if certain considerations are not accounted for implementing them. For example, while increasing block rates have the potential to be effective conservation measures, to remain effective over the long-term they must be keyed to inflation. Demographic factors such as per capita income should also be considered in setting rates. The nominal price of water would have to be raised annually by the rate of inflation plus the rate of change in real income simply to maintain constant rather than increasing water use. There may be considerable variations in the water savings among the demand side measures (10 ~ 30 %). The water conservation (WC)/demand management (DM) principles should be integrated fully into water supply planning, i.e. water potentially produced through increased efficiency and decreased losses should be considered alongside other options at the beginning of supply planning processes. Although the policy and legal framework for implementing WC/DM has been established in many countries, very few measures have been put in place. Water management entities should establish specific targets/standards for water use efficiency and allowable loss for each water sector, and develop strategies to achieve those targets.

Supply Side Management Principal Options and Measures Supply management options refer the actions that affect the quantity and quality of water at the entry point to the distribution system. Principal supply management options include:  

Development of new supply source (surface/groundwater) Cloud seeding

This includes construction of new dams and reservoirs, excavation of ponds, rehabilitation of natural water bodies such as lakes, rivers, and other lowlands. Rubber dam, a flexible and technically and economically sound technology, has been increasingly used in many parts of the world. But in all cases, environmental and ecological perspectives should be taken into consideration. Surface water schemes generally involve one or a small number of water storage and/or diversion facilities. Development of surface-water source includes rainwater harvesting

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through dam, farm pond, lake, and in-situ practices. A centralized structure (such as dam or barrage) can be easily monitored by a public, semi-public or private organization. Development of groundwater source includes identification of aquifer and installation of tubewells, increasing groundwater storage through artificial recharge. In general, large-scale groundwater development requires the construction of a great number of wells and the use of a considerable amount of energy to extract groundwater. In selecting the technologies to be used, a number of factors have to be taken into account which go beyond the physical merits of the technologies themselves, that is, human and financial resources available, compatibility with cultural habits, level of dependence on foreign imports, etc.

Measures of Supply Management Supply management options include the following measures:

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i. Development of surface water source ii. Development of groundwater source iii. Increasing groundwater reserve/storage through artificial recharge iv. Rainwater harvesting v. Sharing of international rivers vi. Treating and using non-conventional water vii. Network rehabilitation viii. Reallocation through volumetric constraints ix. Import of virtual water x. Implementing dual water supply system xi. Clod seeding

Description of Different Measures Development of Groundwater Source For proper development of groundwater, a systematic survey and determination of aquifer characteristics is essential. Groundwater should be withdrawn based on safe yield concept. Safe yield of each aquifer should be determined and groundwater should be exploited accordingly. It is also important to specify the spacing between two discharge wells based on the aquifer properties. Unwise installation of discharge well (i.e. improper design and spacing) causes excessive drawdown and results in less discharge of the well. If the groundwater withdrawal is not based safe yield or greater than the natural recharge (for long-term consideration), groundwater mining (or overdraft) occurs, which causes numerous adverse effects or environmental consequences, such as:      

Failure of suction-mode pump Reduction in stream flow Dry up of ponds and ditches Shallow rooted trees become endanger Degradation of water quality Rising water-tables of polluted water (brackish or saline water) in coastal areas

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Disruption of ecosystem Land subsidence

Development of Surface Water Resource The water can be arrested / harvested from rainfall or surface flow, and then can be stored in canals, dams or water holes. Small dams are normally constructed across the width of the natural channel in hilly areas where the channel width is narrow and the slope is not so high, and the dam can store sufficient water. Earthen, concrete and/or rubber dam can be build depending on the availability of raw material, cost, and economic and technical factors.

Surface Storage and Groundwater Recharge Water from cloud seeding operations or other surplus water that may be available should be stored for later use when water is scarce. Any fresh water that runs into an ocean or other place from where it cannot be recovered is a serious loss where conservation of water is important, ecological considerations notwithstanding. Water can be stored above ground behind dams, or underground in aquifers. Underground storage can be enhanced by increasing the wetted area (width) of streams, using weirs or dams, or constructing levees in the streambed or flood plain.

Rubber Dam – A New Prospect of Surface Water Storage/Harnessing

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Rubber dam is a relatively new technology to harness runoff flow in hilly/sloppy areas. It is a flexible (inflatable and deflatable) hydraulic structure. A unique characteristic of the rubber dam is its ability to function as a reliable minimal maintenance, adjustable-crest gate. The rubber dam has the following advantages over other relevant hydraulic structures: i. ii. iii. iv. v.

Can be quickly deflated, thus facilitating discharge during overflow Low cost Environmentally friendly Adjustable crest gate Requires minimal maintenance

The rubber dam system usually comprises four parts: a. a rubberized fabric bladder, b. a concrete foundation, including upstream and downstream cut-off walls, which are used to lengthen the groundwater seepage path and reduce uplift pressures exerted by groundwater, c. a control house accommodating mechanical and electrical equipment for inflating and deflating the bladder, such as an air blower, water pump, automatic inflation and deflation mechanism, and d. an inlet/outlet pipe system.

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M. H. Ali The schematic view a rubber dam is given in Figure 1.1.

Figure 1.1. Schematic view (cross-section) of a rubber dam.

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In some cases, it may necessary for rubber dam to retain water at both upstream and downstream. Now-a-days, two-side water retaining rubber dam has been built. The following factors should be taken into account for selecting the most suitable site: i. hydrology ii. geology iii. geomorphic condition iv. hydraulic condition v. river sediment vi. meteorology vii. construction difficulties or easiness viii. management difficulties or easiness

Increasing Groundwater Storage through Artificial Recharge Recharge is the process by which groundwater is replenished or riched. It occurs as rain and surface water percolates down through the natural filter constituting fine-grained soil. When a balance between recharge and extraction is maintained, the groundwater aquifer remains static.

Methods of Groundwater Recharge In order to increase in groundwater storage, priority should be given to harvest the excess water. However, the availability of excess water and favorable geo-hydrological conditions are the pre-requisites for successful implementation of such a program. Options of recharge include: a) Recharge from natural water bodies b) Artificial recharge

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Recharge from Natural Water Bodies Exposure of the soil to the water is a must in the recharging process. Water bodies have an important role in recharge. Water from the water bodies continuously seeps into the ground. Artificial Recharge Recharge can be augmented through artificial arrangement. Artificial groundwater recharge through structures may be the most effective means for increasing groundwater potential in the rapidly declining groundwater areas. Artificial recharge includes several ways to recharge, from low cost to high cost involvement:      

Recharge from crop lands by making ridge Recharge through canal water supply during off-irrigation season Recharge through land-overflow/infiltration basin Recharge by making dam/sluice gates Recharge by making large reservoir Recharge through tube-well (recharge well)

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Recharge from Crop-lands by Making Ridge During the period of heavy rainfall or monsoon, farm-lands can be used as a recharge area. If the lands are bounded by high ridges (~30 cm), the water can be percolated downward, and ultimately to the groundwater/aquifer. This is an easy way and involves no additional cost. Only requirement is the initiation and motivation of the mass people. Recharge through Canal Water Supply During Off-Irrigation Season In many regions of the world, rainfall runoff and limited canal water during lean periods of irrigation requirement may be utilized for artificial groundwater recharge. Recharge through Land-Overflow/Infiltration Basin Water can be spread over vast lands (infiltration basin) which can provide opportunity to infiltrate and percolate. Sufficient bunds (barrier) should be provided to hold the water within a regime. The performance of infiltration basins for artificial recharge of groundwater is very sitespecific, and some local experimentation normally is necessary before a system can be designed and operated for maximum performance. Aspects to be studied include the optimum size and depth of the basins, optimum lengths of flooding and drying periods, response of groundwater to recharge, etc. Artificial recharge of groundwater with infiltration basin requires presence and availability of land with sufficiently permeable soils (loamy sands or coarser) to give acceptable infiltration rates. Also, aquifers should be unconfined. Where these requirements are not met, artificial recharge can be achieved with recharge wells.

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Recharge by Making Dam/Sluice Gates Recharge from large land surfaces can be facilitated through stagnating water by artificial barrier. The barrier may be sluice gate, dam or other forms depending on the catchment size, outlet and other physiographic and hydraulic condition. Recharge by Making Large Reservoir Recharge area can be established by making large reservoir in suitable low-land area, where water is compounded or provided, and thus facilitating recharge for long time.

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Recharge through Recharge Well Large amount of water can be recharged through recharge well. In many regions of the worlds, although the region may have moderate or low average rainfall, high intensity rainfall creates flash flood that goes to sea as waste. Such flash floods need to be arrested at various locations for recharge at accelerated rate. In flat topography, where extensive groundwater development has taken place at shallow depth, recharge structures with tubewell are often better choice than surface storage. In areas having alluvial aquifers with good transmissibility, hydraulic conductivity and specific yield; recharge tubewells improve water quality and availability more quickly than gradual percolation from percolation tank or check dams. During construction of recharge well, a filter pit is to be excavated and filled with filter material. Filter materials should be designed properly, so that suspended solids and contaminants can not enter to the aquifer. The filter materials would be in the order - pebbles at the bottom, then gravels, and then coarse sand at the top (Figure 1.2). Mechanical analysis of the base material (soil from the canal bed or surrounding soils) should be made for proper design of filter. Even then, recharge wells tend to become clogged and must be cleaned or redeveloped. For wells in alluvial materials, specific capacities for recharge wells often are only 25 to 75 % of those for pumping wells. Rainwater Harvesting Rainwater harvesting can be defined as the collection of rainfall or rainfall runoff for agricultural production or domestic purposes or livestock watering. In areas where there is inadequate groundwater supply, or surface resources are either lacking or insufficient, rainwater harvesting offers an ideal solution. Countries like Germany, Japan, United States, and Singapore are adopting rainwater harvesting. Productivity of rainfed agriculture can be improved through supplemental irrigation via water harvesting. Rainwater harvesting in existing local ponds, and use them for dry-season cropping (particularly low water demanding crops, such as pulses, oilseed, wheat) seems a prospect in dry area.

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Figure 1.2. Schematic of a recharge well. Various forms of rainwater harvesting have been used traditionally throughout the centuries. The importance of traditional, small-scale systems has recently been recognized. The potential of water harvesting for improved crop production received great attention in the 1970s and 1980s. This was due to the widespread droughts in Africa which left a trial of crop failures and a serious threat to human and livestock life. The pre-determined condition for rainwater harvesting in any area is that the area has sufficient rainfall in storms of considerable intensity, with intervals during which there is practically no or very little rainfall. It requires adequate provision for the interception, collection and storage of the water. Depending on the circumstances, the catchment of the water is on the ground or building roofs.

Techniques of Rain-Water Harvesting Various techniques have been evolved for harvesting rain-water. These include from traditional or ancient technique to modern rubber dam. Selection of appropriate technique for a site depends on various factors such as source (distance) and amount of rain-water, soil condition, technical and socio-economic condition. Rain-Water Harvest from External Catchment This system involves the collection of runoff from external areas which at an appreciable distance from where it is being used. Runoff from natural drainage is diverted towards collection point through diversion ridge. The runoff water is sometime conveyed through structures of diversion and distribution networks. This is sometimes used with intermediate storage of water outside the catchment basin for later use as supplementary irrigation.

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In-Situ Rain-water Harvest This may be accomplished by deep tillage, contour farming, agronomic practices, mulching, or a combination. This approach works better where the water holding capacity of the soil is higher and organic matter is rich. The stored soil moisture may be sufficient for germination, establishment and maturity of some dry-land crops. In in-situ rain-water harvesting, high volume of runoff can not be stored in soil profile. Deep tillage increases water holding capacity of soil through increasing porosity and infiltration rate, and facilitate root elongation. Thus moisture and nutrient uptake from deeper layer increases. Mulching through crop residues reduces surface runoff and evaporation loss from the soil profile. Tillage mulching of top few centimeter soil breaks the capillary channel of water movement, thus reduces moisture loss through evaporation.\

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Harvesting in Farm-Pond In this approach, a suitable size pond is constructed at a corner or centre of the individual farm. Water is stored in this pond during monsoon period or from heavy rainfall events. Water can also be harvested through runoff collection. Rainwater harvesting can be a valuable practice in creasing crop production in semi-arid regions. It is also useful in humid and sub-humid region during dry or off-monsoon period, and even in monsoon for long dry-spell. In semi-arid region, water harvested in a farm-pond can be used to irrigate low water demanding crops and irrigating only at critical growth stages (which is sensitive to water stress/deficit). Supplemental irrigation from farm pond during dry spell can ensure sustained and higher crop yield. Sharing of International Rivers More than 300 major river basins across national boundaries exist worldwide, which comprise about half of the total land of the world. The large river basins are shared by several countries. International treaty should be accomplished and employed to share the water among the countries. Good relation should be established among the countries in terms of cultural, trade, and other levels. If needed, some sort of sacrifice in other sectors may be allowed to hold the good relation and get share of the water. Bilateral and multilateral environmental agreements should be accomplished and employed to deal with trans-boundary freshwater issues. Network Rehabilitation Initiation of rehabilitation projects for municipal supply network would save water. This option would be the easiest to implement and would bring overwhelm social acceptance. Similarly, reducing conveyance loss in irrigation system provides a large savings and hence, an increase in supply at the user point. Reallocation through Volumetric Constraints The process of reallocating water from agriculture to cover deficits in household and industrial uses, or lower value crops to higher value crops may be an option to manage the scarce water resource.

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Import of Virtual Water High water-demanding crops may be avoided to grow, rather low water-demanding crops may be grown and import the high water-demanding crops (the virtual water). This technique lowers the demand and hence, increases the supply for the others.

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Dual Water Supply System Where good-quality water is available in limited quantity and transported over long distances, it may be economical to conserve this water for only potable use and to employ recycled water for other uses. In dual supply systems, two grades of water (one potable and the other sub-potable or non-potable) are supplied to consumers through separate distribution systems in accordance with quality and quantity requirements. Since only a fraction of household water must be of potable quality, the volume of water to be treated by an expensive and sophisticated process is also small, allowing economy in treatment. Cloud Seeding Cloud seeding is a technique for conserving water because clouds moving over an area without producing rain is a form of water loss for that area. Much work has been done over the years about the efficacy of cloud seeding. The picture emerging from these studies is that cloud-seeding should be done during rainy periods to increase precipitation so that it can be stored for future use. If cloud seeding is delayed until there is drought, there usually are not enough seedable clouds to produce significant increases in rain. Orographic storms are much more productive for seeding than convective storms. In the western United States, seeding of orographic storms is excepted to increase precipitation from those storms by 10 to 15 percent (the percentage increase is higher in dry years than in wet years). The preferred seeding technique is with ground generated silver iodide crystals. Seeding from airplanes is much more expensive. Since only about 5 percent of the water in orographic storm-clouds falls on the ground as natural precipitation, a 10 to 15 percent increase in precipitation due to cloud seeding would still leave plenty of water in the clouds for areas downwind from the seeded areas. Depending on local conditions, the economic aspects of cloud seeding can be quiet favorable. For a program under development in Arizona for example, cloud seeding produced $9 to $12 worth of water for every dollar invested in the seeding program. Use of Non-Conventional Water Contaminated water, sewage and municipal discharge, drainage outflow, and saline water may be considered for use in agriculture after appropriate treatment and/or management. Water reuse after treatment is not new concept. On-farm recycling of irrigation water is becoming more common. Treated effluent can also be used for recharging groundwater aquifers, and for maintenance of stream flows and wetland conditions. In water-short areas, usually there is no single solution for solving problems of inadequate water supplies. Rather, a broad approach is needed, saving water, using water more efficiently, and reusing water wherever possible. Only then can limited water supplies in arid and semiarid regions be effectively managed.

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4. WATER CONSERVATION MEASURES Concept of Water Conservation Water conservation is a special form of water management for water short areas, where water must be used as efficiently as possible and water losses must be minimized. A water loss is defined as the transfer of water to a place or condition from which it cannot readily be recovered for further use. Such losses include evaporation and transpiration, discharge of fresh water into salt water (oceans, lakes, or aquifers), storage or transit in the vadose (unsaturated) zone, and serious pollution by industrial, agricultural, or other chemicals.

Principles or Approaches of Water Conservation Water conservation can be achieved by:

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       

reducing evaporation reducing transpiration/evapotranspiration reducing seepage reducing quality degradation cloud seeding increasing groundwater recharge or other storage treating and reusing sewage or other contaminated water using super-absorbents

Description of Different Approaches Reducing Evaporation Water surfaces: Evaporation from open water bodies can be reduced by covering them with monomolecular layers of hexadecanol or octodecanol. Water loss can be more successfully reduced with floating objects in small reservoirs. Floating sheets of foam, rubber have been successfully used. Evaporation reductions of close to 100 percent have been obtained with such covers. Evaporation from open water surfaces can also be reduced by reducing the area of the water surface. For small surface storage facilities, this can be achieved by storing the water in deep, small reservoirs instead of in shallow, large reservoirs. For larger facilities, several ponds or compartmentalized ponds have to be available. When water levels in the ponds begin to drop, water is then transferred between ponds or between compartments so that only one or a few deep ponds are kept full while the others are dry, thus minimizing the water surface area per unit volume of water stored. If the ponds are unlined, the effect of water depth on seepage loss from the pond must be taken into account.

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From a hydraulic standpoint, increasing the water depth would increase seepage the most if there is a layer of sediment or other clogging material on the pond wetted perimeter through which most of the head due to water depth is dissipated. Water depth in the pond also has a significant effect on seepage if the ground water table is higher than the pond bottom. This situation, however, is unlikely to occur in water-short areas.

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Dry-Land Farming Evaporation from soil is reduced by dry-land farming techniques that are aimed at conserving water in the root zone during the fallow season for use by the crop in the next growing season. The main strategies are weed control, tillage, and leaving the stubble or other crop residue in the fields during the dry or fallow season. Weed control prevents transpiration losses. Tillage is primarily needed on heavy soils that may crack during fallow and lose water by evaporation through the cracks. The purpose of the tillage, then is to close the cracks. Sands and other light-textured soils that do not crack are ―self-mulching‖ and do not need tillage. Leaving the stubble or crop residue on the field during fallow periods reduces evaporation losses from the soil by lowering soil temperature and reducing wind velocities close to the soil surface. Finally, evaporation of water from soil surfaces can be reduced by reducing the extent of wet areas from which water evaporates. In irrigated fields with incomplete crop covers (row crops in the beginning of the growing season, vineyards, orchards), evaporation from soil can be reduced by irrigating only the areas near the plants and leaving the rest of the soil (surface or subsurface). This can be accomplished, for example, with drip irrigation systems (surface or subsurface).

Reducing Evapo-Transpiration Irrigation Efficiency Most of the irrigation systems are surface or gravity systems, which typically have efficiencies of 60 to 70 percent. This means that 60 to 70 percent of the water applied to the field is used for evapo-transpiration by the crop, while 30 to 40 percent is ―lost‖ by surface runoff from the lower end of the filed and by deep percolation of water that moves through the root zone. Field irrigation efficiencies of gravity systems can be increased by better management of surface irrigation systems (changing rate and/or duration of water application), modifying surface irrigation systems (changing the length or slope of the field, including using zero slope or level basins), or by converting to sprinkler or drip irrigation systems where infiltration rates and water distribution patterns are controlled by the irrigation system and not by the soil. Surface irrigation systems often can be designed and managed to obtain irrigation efficiencies of 80 to 90 percent.

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Thus, it is not always necessary to use sprinkler or drip irrigation systems when high irrigation efficiencies are desired.

Irrigation Scheduling Improved scheduling of irrigation conserves water only if runoff and/or deep percolation from the irrigated fields cannot be reused. Scheduling of irrigation can be based on sol water measurements (tensions and/or contents), or on estimates of daily evapotranspiration rates using climatological methods, evaporation pans, or lysimeter. Measurement of the plant water status through remotely sensed plant or crop canopy temperatures with infrared thermometers, shows promise as a technique for scheduling irrigations. This approach also requires measurement of relative humidity and temperature of the ambient air. Better timing of irrigation could also increase crop yields per unit of evapotranspiration, thus increasing crop water use efficiencies. Antitranspirants Spraying plants with antitranspirants may have some application for ornamental plants (lawns and shrubs) where production or fast growth is not important. For agricultural crops, however, a reduction in transpiration usually also means a severe reduction in yield. Thus, antitranspirants generally are not feasible for reducing water use of agricultural crops.

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Natural Vegetation and Phreatophytes Considerable amounts of water are used by natural vegetation. To reduce evapotranspiration of natural vegetation, deep-rooted plants (trees) can be replaced by shallow-rooted plants (grasses). Water use by phreatophytes can be reduced by removing them from the flood plain (eradication). Seepage Control As irrigation is the largest water use sector, it is of great importance to reduce wastage. Unlined irrigation canals not only loss water, but also creates salinity problems to the adjacent land. Lining channels with concrete has the added advantage of providing better weed control and canal maintenance. The following measures may be undertaken: a) b) c) d)

Lining of earth channels by concrete. Replacing of channels by pipelines. Applying high efficiency irrigation systems such as drip, sprinkler and spray. Application of water meters to measure the water used and charging of water rates in the case of government projects, so that the farmer would become careful in wasting water.

Reducing Quality Degradation Degradation of quality to the point where water can no longer be used for its intended purpose or is no longer suitable for beneficial use in general, is another form of water loss. Such losses occur when fresh water is polluted or when fresh water is discharged into salt

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water or seeps down to saline aquifers from where it no longer can be separately recovered. Where water is scarce and water conservation is a necessity, such losses should be minimized. Another example of quality degradation is urban use of water, which converts fresh water to sewage effluents.

Using Super-Absorbents Super-absorbents have the ability to make more efficient use of water, by extending the period in which soil moisture is available to plants, and by trapping gravitational water which would normally be lost to plants in free draining soil. Their main function is to reduce moisture stress and transplant shock, thus creating optimum moisture conditions for plant growth. The water-holding capacity of the various super-absorbents ranges from 30 to 1000 times their own weight of water. Super-absorbent compounds are available in two basic forms (Gallacher, 1984): a) Biodegradable powders or flakes with an in-ground life span of six to 18 months. These are a combination of natural cereal-starch polymers grafted to synthetic starch polymers. Some will break down after exposer to ultraviolet rays. b) Non-degradable cross-linked acrylamide copolymers with a potentially indefinite life span.

Applications of Super-Absorbents

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Super-absorbents can be used in four basic ways: i. ii. iii. iv.

Adding to growing media in the dry form. Broadcasting over surfaces prior to planting or seeding. As a gel dip when combined with water. As a seed coating.

In landscape construction, super-absorbents can be used as establishment aids for trees, shrubs, lawns and instant application. Trees and shrubs are probably best treated with biodegradable absorbents, as these will assist in the first year of the plant‘s life and the effects will gradually diminish, enabling the plant to fully adapt to its new environment. The longlife polymers are ideally suited to use in lawn and instant turf establishment, where shallowrooted grasses will obtain maximum benefit. Nurseries can benefit by incorporating superabsorbents into soil mixes, to reduce watering of plant stock and enable plants to retain water for longer periods when being transported.

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5. INCREASING WATER PRODUCTIVITY IN CROP PRODUCTION Background and Concept of Water Productivity Scarce water resource and growing competition for water will reduce its availability for irrigation. Effective management of water for crop production in water scarce areas requires efficient approaches. Increasing crop water productivity (WP) and drought tolerance by genetic improvement and physiological regulation may be the means to achieve efficient and effective use of water. Water productivity (WP) can be expressed as agricultural production per unit volume of water, i.e. WP = Agricultural production / water applied The numerator may be expressed in terms of crop yield (kg ha-1) or, when dealing with different crops, yield may be transformed into monetary units (i.e. $/ha-1). Water productivity is an indicator of best irrigation scheduling with deficit supplemental irrigation of cereals, in analyzing the water saving performance of irrigation systems and management practices, and to compare different irrigation systems, including deficit irrigation. Water productivity can be divided into irrigation water productivity (IWP) and water productivity (WP), as follows: IWP = Grain or seed yield / irrigation water applied , (kg/ha-cm)

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WP = Grain or seed yield / crop evapo-transpiration , (kg/ha-cm)

Factors Affecting Water Productivity From the above formulation of IWP or WP, it is revealed that, the factors which affect or influence crop yield, and water applied or need to be applied, obviously affect or influence the water productivity. The factors are (Ali and Talukder, 2008):    

Crop cultivar type Amount of applied water Remobilization of pre-stored carbon, the variable fraction in grain filling Soil factor

Techniques to Improve WP Many technologies to improve WP and the management of scarce water resources are available. Among the most promising and efficient proven techniques is deficit irrigation for optimizing the use of the limited water. The main pathways for enhancing WP along with targeted yield with limited irrigation are to increase the output per unit of water (engineering

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and agronomic management aspects), reduce losses of water to unusable sinks, reduce water degradation (environmental aspects), and reallocate water to higher priority uses (social aspects). Improving crop water productivity, however, requires exploiting not only water management but rather all other inputs such as improved germplasm, fertility and cultural practices which influence yield.

Deficit Supplemental Irrigation There are different ways to manage deficit irrigation. The irrigator can reduce the irrigation depth, refill only part of the root zone, reduce the irrigation frequency by increasing the interval between successive irrigation, refill a fraction of the soil water capacity of the root zone, wetting furrows alternately or placing them further apart.

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Proper Sequencing of Water Deficit Optimal sequencing of water deficit reduces the detrimental effect on yield, and hence increase WP. Liang et al.(2002) demonstrated that the drying-rewatering alteration (alternate deficit) had a significant compensatory effect that could reduce transpiration and keep wheat growing and WP significantly increased under drought conditions. Ali et al. (2007) obtained highest WP and IWP in alternate deficit treatment in wheat. If a certain amount of water deficit is at hand, it should be spread out in whole growth period with alternate wetting and drying. When plants are subjected gradually to water stress, hardening processes take place which make plants less sensitive to renewed water stress by osmotic adjustment of the leaves, by influencing leaf morphology, and change in the elastic modulus of leaf cells. Osmotic adjustment allows for the maintenance of photosynthesis and growth by stomatal adjustment and photosynthetic adjustment. Increasing Soil Fertility Liu et al. (1998) indicated that maximum yield and highest WP were achieved under the optimum fertilizer input in the semiarid field conditions of loess hilly area in Ningxia. By Improving Assimilate Partitioning to Grain (By Increasing Harvest Index and Harvest Ratio) In most crops (especially in cereals), the farmers are interested to produce higher grain yield, but not the straw yield. Zhang et al. (1998) found with field-grown wheat that, a soil drying during the grain filling period enhance early senescence. They found that while the grain filling was shortened by 10 days (from 41 to 31 days) in unwatered (during this period) plots, a faster rate of grain-filling and enhanced mobilization of stored carbohydrate minimized the effect on yield. Zhang and Yang (2004) showed that WP may be enhanced through an improved harvest index (HI). Ali et al. (2007) found highest HI, harvest ratio and IWP with alternate deficit treatment, having drying at grain filling stage. Wet-seeded or Direct-Seeded Rice The wet-seeded or direct-seeded technique is an alternative to the transplanting method of rice crop establishment. This technique increases productivity and water use efficiency.

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Priming of Seed The technique of seed priming, where the seed is soaked in water (usually overnight), then surface dried and then sown, has been shown to improve plant stands and provide benefits in terms of earlier maturity and increased seed yield in a range of crops (wheat, maize, lentil, chickpea, etc.) in rainfed as well as irrigated crops grown on normal soils. This technique reduces the post-sowing or pre-sowing irrigation needs and saves water. Besides, priming had a significant positive effect on yield. Application of Farmyard Manure / Organic Matter Nitrogen management is one of the major factors to attain higher productivity (which in turn increase WP) in dry-land farming, particularly under limited water supply, where use of higher dose of inorganic fertilizers is restricted. Under such conditions, organic source of nitrogenous fertilizer such as farmyard manure, bio-fertilizer are more appropriate. Legumebased cropping system can enhance fertility status through addition of atmospheric nitrogen. Incorporation of organic matter/farmyard manure, a way of improving soil physical and chemical conditions, could increase water-holding capacity for a more efficient water use. Organic matter/manure improve water storage properties, and release water slowly, facilitating proper crop growth and thus increase yield and water productivity.

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Other Management Factors Among the management factors for more productive farming systems are the use of improved or suitable crop rotation, sowing dates, crop density, mulching, weed control, pests and disease control. Mulching with crop residues during the summer fallow can increase soil water retention. Tillage Increasing water storage within the soil profile is necessary to increase plant available soil water. Tillage roughness the soil surface and breaks any soil crust. This leads to increased water storage by increased infiltration. Promoting water-saving agriculture is not only able to increase water productivity, but can also facilitate the structural adjustment needed by agriculture. Combining biological watersaving measures (drought tolerance by genetic improvement and physiological regulation) with engineering solutions, and soil and agronomic manipulation may solve the problem to a certain extent.

6. SUSTAINABILITY ISSUES IN WATER RESOURCE MANAGEMENT Water sustains life. It is our duty to sustain all sources of water. Scarcity and misuse of fresh water pose a serious and growing threat to sustainable development and protection of the environment. Human health and welfare, food security, industrial development, and the ecosystems on which they depend, are all at risk, unless water and resources are managed more effectively at present and beyond what they have been in the past.

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Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations. Sustainable water management and development is defined as a set of actions to secure the present functions of water without jeopardizing the interests of future generations. Sustainable management implies managing for the long-term. Water resources systems that are able to satisfy to the extent possible the changing demands placed on them over time, without system degradation, can be called ‗sustainable‘. Sustainability as defined in the Brundtland Commission‘s report ‗Our Common Future‘ (WCED, 1987) focuses on meeting the needs of both current and future generations. Development is sustainable if,

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―.. it meets the needs of the present without compromising the ability of future generations to meet their own needs.‖

Since the Brundtland report of 1987, sustainable development has become the subject of discussions and debates throughout the world. While the world ―sustainability‖ can mean different things to different people, all would agree that it includes a consideration of the future. The Brundtland Commission was concerned about how our actions today will affect, ―..the ability of future generations to meet their needs.‖ The question arises ‗what will those needs be?‘. We today can only guess as to what they may be. We can also argue over whether or not it is appropriate to try to meet present or future needs if they over-stress the system designed to meet them. Another question arises, ―over what time and space scales should we do it ?‖ How do we allocate over time and space our renewable resources, i.e. the waters that exist in many deep groundwater aquifers that are not being replenished by nature? To preserve non-renewable resources now for the use of our descendants in the future, in the interests of sustainability, would imply that those resources should never be consumed as long as there is a future. If permanent preservation seems unreasonable, then how much of a non-renewable resource might be consumed, and when? It raises the question; does everything need to be sustained? If not, just what should? And over what spatial and temporal scales should sustainability considerations apply? Obviously we do enhance the welfare of future generations by preserving or enhancing the current state of our natural environmental resources and ecological systems. The debate over the definition of sustainability is among those who differ over just what should be sustainable and how to achieve it. ASCE (1998) defined sustainability in water resources as: ―Sustainable water resource systems are those designed and managed to fully contribute to the objectives of society, now and in the future, while maintaining their ecological, environmental, and hydrological integrity‖.

Sustainable water resource systems are those designed and operated in ways that make them more adaptive, robust, and resilient to the changes in the natural system due to geomorphological process, changes in the engineered components due to aging and improved technology, changes in the demands or desires due to a changing society, and even changes in the supply of water, possibly due to a changing climate. In the face of changes and uncertain impacts, an evolving and adaptive strategy is a necessary condition of sustainable water resources management. Adaptive management is a process of adjusting management actions and directions, as appropriate, in light of new information on the current and likely future

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condition of our total environment and on our progress toward meeting our goals and objectives. Sustainable issues are not new issues, nor is sustainability a new concept. Yet the current interest in sustainable water resources management clearly comes from a realization that some of the activities that we who inhibit this earth today perform could be causing irreversible damage. This damage may have adverse effect not only our own lives but also the lives of those who follow us.

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REFERENCES Ali, M.H., Talukder, M.S.U. (2008). Increasing water productivity in crop production – A synthesis. Agric. Water Manage. 95: 1201 – 1213. Ali, M.H., Hoque, M.R., Hassan, A.A., Khair, M.A.(2007). Effects of deficit irrigation on yield, water productivity, and economic returns of wheat. Agric. Water Manage. 92, 151161. ASCE Task Committee for Sustainable Criteria (1998). Sustainable criteria for water resource systems. ASCE Division of Water Resources Planning and Management, ASCE Press, Reston, VA, 253pp. Gallacher, B (1984) An alternative water management technology for landscaping. Landscape Australia 3: 184-186. Hayes, M.J., Svoboda, M.D., Wilhite, D.A., Vanyarkho, O.V. (1999). Monitoring the 1996 drought using the standardized precipitation index. Bull. Am. Meteorol. Soc. 80: 429-538. Liang, Z. S., Zhang, F.S., Zhang, J. H. (2002). The relations of stomatal conductance, water consumption, growth rate to leaf water potential during soil drying and rewatering cycle of wheat. Botanical Bull. Academia Sinica 43: 187 –192. Liu, Z.M., Shan, L., Deng, X.P., Inanaga, S., Sunohara, W., Harada, J. (1998). Effects of fertilizer and plant density on the yields of root system and water use of spring wheat. Research of Soil and Water Conservation 5(1): 70-75. Palmer, W.C. (1965). Meteorological drought. Res. Paper no.45. U.S. Dep. of Commerce Weather Bureau, Washington, DC. Palmer, W.C. (1968). Keeping track of crop moisture conditions, nationwide: The crop moisture index. Weatherwise 21: 156-161. Zhang, J., Sui, X., Li, B., Su, B., Li, J., Zhou, D. (1998). An improved water use efficiency for winter wheat grown under reduced irrigation. Field Crop Res. 59: 91-98. Zhang, J., Yang, J. (2004). Improving harvest index is an effective way to increase crop water use efficiency. In: Proc. 4th Int. Crop Sci. Congress, held at Brisbane, Sept. 2004, on the theme ―Crop Science for Diversified Planet‖.

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Chapter 3

WATER MANAGEMENT IN SALT-AFFECTED AREAS M. H. Ali* Agricultural Engineering Division, Bangladesh Institute of Nuclear Agriculture (BINA), BAU Campus, Mymensingh, Bangladesh

1. BACKGROUND

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1.1. Extend of Salt Affected Soils Excess salt ions in the soil or from irrigation water can cause salinity and limit agricultural production. Saline soils are found throughout almost all parts of the world. Soil salinization has been identified as a major process of land degradation. Based on the FAO/UNESCO Soil Map of the World, the total area of saline soils is about 394 million hectare and that of sodic soil is 434 million hectare (ha). Soil salinization is the accumulation of free salts in soil to such an extent that it leads to degradation of soils and vegetation. The salts originate from the natural weathering of minerals or from fossil salt deposits left from ancient sea beds. Salts accumulate in the soil of arid climates as irrigation water or groundwater seepage evaporates, leaving minerals behind. Irrigation water often contains salts picked up as water moves across the landscape, or the salts may come from human-induced sources such as municipal runoff or water treatment. As water is diverted in a basin, salt levels increase as the water is consumed by transpiration or evaporation. Countries experiencing salt problem include Australia, Argentina, Bangladesh, Canada, India, Pakistan, Thailand, South Africa, Turkey, USA, etc. Understanding the soilsalinization processes and limitations is the key to improvements and helps in taking amelioration measures.

* Dr. M. H. Ali, Agricultural Engineering Division, Bangladesh Institute of Nuclear Agriculture (BINA), BAU Campus, Mymensingh 2202, Bangladesh, Email: [email protected], [email protected] Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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1.2. Classification of Saline Soils and Water 1.2.1. Classification of Saline Soils Classification Based on Development Mode Based on the mode of development, salinity can be grouped as: 1. Primary salinity 2. Secondary salinity

Primary Salinity This form of salinity is developed naturally, as a result of long-term continuous discharge of saline groundwater, or from rocks having high salt content, or from the sea base material deposits. These soils often have high EC (electrical conductivity) values. Secondary Salinity This type of salinity is man-made, and is the result of human activities that have changed the local water movement patterns of an area. Soils that were previously non-saline have become saline due to changes in saline groundwater discharge. This type of soil may have lower EC values and may be improved with management. Classification Based on Sodium and SAR Salt-affected soils may be divided into three groups depending on the amounts and kinds of total soluble salts present and exchangeable sodium percentage (ESP) (Table 1): Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved.

Table 1. Generalized classification of salt-affected soils Soil class Saline soil Sodic (alkali) soil Saline-sodic soil Note: Normal soil- EC < 2 dS/m, ESP < 15

EC (dS/m) >2 2

Criteria ESP < 15 > 15 > 15

pH < 8.5 > 8.5 < 8.5

Saline Soil Salinity refers to the amount of salts in soils. Saline soils are high in soluble salts but low in sodium. When a solution extracted from saturated soil is 2.0 dS/m or greater, the soil is saline. This soil is commonly referred to as white-alkali soil due to the formation of white crust on soil surface. Crop losses may occur with irrigation water containing as little as 700 to 850 mg/L TDS (total dissolved solids) or EC>1.2 dS/m. Sodic Soil Sodicity refers to the amount of sodium in soils. Sodic soils are low in soluble salts but high in sodium. This soil is commonly referred to as ‗black alkali soil‘.

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Saline-Sodic Soil These soils contain large amounts of total soluble salts and greater than 15 percent exchangeable sodium. The pH is generally less than 8.5. Physical properties of these soils are good as long as an excess of soluble salts is present. Effective management of salinity or sodicity problem requires correct diagnosis of the problem. A salt-alkali soil test should be established to identify whether the soil is saline, sodic, saline-sodic, or not affected by salts. An examination of the soil profile along with soil survey information will help to determine soil permeability characteristics, which are important in leaching salts.

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1.2.2 Classification of Saline Water Richards (1954) classified irrigation water based on electrical conductivity (EC) and sodium absorption ratio (SAR), and the classification was shown in a diagram (Fig. 1).

Figure 1. Diagram for the classification of irrigation water (after Richards, 1954)

CAUSES OF SALINITY DEVELOPMENT Salinity problems are caused from the accumulation of soluble salts in the root zone. The problems include high total salts, excess exchangeable sodium, or both. Originally salts came

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from the weathering of rocks that contain salt. In some areas (for example in Australia), salinity is an inherent situation (enormous amounts of salts are stored in the soils). However, human practices have increased the salinity of top soils by bringing salt to the surface through disrupting natural water cycles, by allowing excess recharging of groundwater and accumulation through concentration. Sodicity is generally dependent on the parent material from which a soil is formed and is found on older soils where there has been sufficient weathering of clay minerals to cause a dominance of sodium. The most common salts in soil include chlorides, sulfates, carbonates and sometimes nitrates of calcium, magnesium, sodium and potassium. Generally, it is a natural process, and may results from:

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      

high levels of salt in soil‘s parent materials irrigation with saline water shallow saline groundwater landscape features that allow salts to become mobile (movement of water table) climatic conditions that favor accumulation of salts land-use practice & rainfall pattern man-made activity

The development of saline soils is related to the flow of groundwater. As the groundwater flows between particles of rock and soil, it dissolves and transports soluble salts. The groundwater emerges at the soil surface in a discharge area. When the water evaporates, the salts are left behind on the soil surface. Over time, the salts accumulate in the discharge area, and eventually the salt concentration becomes so high that plant growth is restricted. Groundwater can also move under unsaturated conditions through the smaller soil pores by the process of adhesion. That is, when soil moisture content is close to field capacity, soil particles will yield water molecules to other soil particles with lower moisture levels. Unsaturated flow is common around sloughs, dugouts and other water bodies. Like saturated flow, it can dissolve and transport salts to the soil surface. For saline soils to form, the water table needs to come close enough to the soil surface to allow capillary action to raise the groundwater to the soil surface. In general, the water must be within 2 m (6 ft) of the soil surface for this to occur, but the critical depth varies with soil texture. In Australia, salts (mainly sodium chloride) occur naturally at high levels in the subsoils of most Australian agricultural land. Some of the salts in the landscape have been released from weathering rocks, but most have been carried inland from the oceans on prevailing winds and deposited in small amounts with rainfall and dust. Over years, it has accumulated in sub-soils. In other countries, the causes and sources of dry-land salinity are similar in some cases (e.g. north-east Thailand, parts of South Africa) but different in others. Knowing the source of salt problems can be helpful in diagnosing and managing salt-affected fields. Generally, the tests required for identification of salinity or sodicity are given in Table 2.

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Table 2. Test requires for different problem identification. Tentative problem Test required Suspect a salinity or sodicity problem Soil EC, pH, SAR, ESP A salinity problem exists Soil EC, irrigation water EC, consider spatial mapping of field EC A sodicity problem exists ESP, and/or SAR

3. IMPACT OF SALINITY AND SODICITY The consequences of salinity are detrimental effects on plant growth and final yield damage. Salinity causes damage to the soil structure - including dispersion, erosion and water-logging. This reduces plant available water content (PAWC) and root depth for dryland agriculture. When crops are too strongly affected by the amounts of salts, it disrupts the uptake of water into roots and interferes with the uptake of competitive nutrients. Sodic soils are low in total salts but high in exchangeable sodium. The combination of high levels of sodium and low total salts tends to disperse soil particles, making sodic soils of poor tilth. These soils are sticky when wet, nearly impermeable to water. Dispersion occurs when the clay particles swell strongly and separate from each other on wetting. Crop growth and development problems on sodic soils can be nutritional, associated with poor soil physical conditions, or both. Plants on sodic soils usually show a burning or drying of tissue at leaf edges, progressing inward between veins.

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4. RELATIVE SALT TOLERANCE OF CROP Some crops are more sensitive to salinity stress than others. Crops such as pulses, and some other crops are particularly sensitive to salinity. The salt tolerance of some crops changes with growth stages. The factors influencing tolerance to crop are:      

Variety or species Growth stage Environment Salinity-stress history or sequence of salinity stress Moisture condition Soil type

Variety Crops differ in their ability to tolerate salt accumulation in soils, but if levels are high enough (> 12 dS/m), only tolerant plants will survive. The wheat is genetically moderately tolerant to salinity (6~8 dS/m) (Ali and Rahman, 2009a).

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Rice has long been grown in the coastal regions of India and other countries where salinity is a perpetual problem due to inundations from the sea, and intrusion of sea water through rivers, estuaries, etc.

Growth Stage All growth stages of crop are not similar in their response to salinity stress. Most plants are more sensitive to salinity during germination than at any other growth stage (Table 3). However, there are large variations in the sensitivity of germinating seeds to salinity. Some crops are sensitive at flowering to fruit formation stages. Table 3. Tolerance of crops to salts at two stages of growth (Canada Department of Agriculture, 1977). Crop

Degree of tolerance at

Wheat

Germination stage Fairly good

Establishment stage Fair

Barley

Very good

Good

Sugarbeet

Very poor

Good

Beans

Very poor

Very poor

Alfalfa

Poor

Good

Table 4. Yield potential of selected crops as affected by soil salinity (ECe) or irrigation water salinity (ECw) (Adapted from Mass and Hoffman (1977), and Mass (1984)).

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Crop Rice (Oriza sativa) Wheat (Triticum aestivum) Wheat, durum (Triticum turgidum) Corn (maize) (Zea maize) Sorghum (Sorghum bicolor) Sugarbeet (Beta vulgaris) Barley (Hordeum vulgare) Potato (Solanum tuberosum) Tomato (Lycopersicon esculentum) Sugarcane (Saccharum officinarum) Soybean (Glycine max) Cotton (Gossypium hirsutum) Onion (Allium cepa) Carrot (Daucus carota) Cabbage (Brassica oleracea capitata) Bean (Phaeseolus vulgaris) Sweet potato (Ipomoea batatas) Alfalfa (Medicago sativa) Barley (forage) Corn (forage) (maize) (Zea maize) Wheatgrass, tall (Agropyron elongatum) Sudan grass (Sorghum sudanese) Bermuda grass (Cynodon dactylon) Date palm (phoenix dactylifera) Grape (Vitus sp.) Orange (Citrus sinensis)

Yield potential 100 % ECe 90 % ECw ECe ECw 3.0 2.0 3.8 2.6 6.0 4.0 7.4 5.0 5.7 3.8 7.6 5.0 1.7 1.1 2.5 1.7 6.8 4.5 7.4 5.0 7.0 4.6 8.7 5.8 7.9 5.2 10 6.7 1.7 1.1 2.5 1.7 2.5 1.7 3.5 2.3 1.7 1.1 3.4 2.3 5.0 3.3 5.5 3.7 7.7 5.1 9.6 6.4 1.2 0.8 1.7 1.2 1.0 0.7 1.6 1.0 1.8 1.2 2.8 1.9 1.0 0.7 1.5 1.0 1.5 1.0 2.4 1.6 2.0 1.3 3.4 2.2 6.0 4.0 7.4 4.8 1.8 1.2 3.2 2.1 7.5 5.0 9.8 6.5 2.7 1.8 5.0 3.4 6.9 4.6 8.5 5.6 4.0 2.6 6.8 4.5 1.5 1.0 2.5 1.7 1.6 1.0 2.3 1.6

75 % ECe ECw 5.1 3.4 9.5 6.3 10 6.9 3.8 2.5 8.4 5.6 11 7.4 13 8.7 3.8 2.5 5.0 3.4 5.9 4.0 6.3 4.2 13 8.4 2.8 1.8 2.8 1.9 4.4 2.9 2.3 1.5 3.8 2.5 5.3 3.5 9.5 6.5 5.2 3.5 13 9 8.6 5.7 11 7 11 7.2 4.0 2.6 3.3 2.1

50 % ECe ECw 7.2 4.8 13 8.7 15 10 5.9 3.9 9.9 6.7 15 10 18 12 64 7.6 5.0 10 6.8 7.5 5.0 17 12 4.3 2.9 4.6 3.0 7.0 4.5 3.6 2.4 64 96 13 8.6 8.6 5.7 19 13 14 9.6 15 9.7 18 12 6.6 4.5 4.8 3.3

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0% ECe ECw 11 7.7 20 13 24 16 10 6.8 13 8.7 24 16 28 20 10 6.8 13 8.4 19 12 10 6.8 26 18 7.4 5.0 8.0 5.5 12 8 6.3 4.3 11 7 16 10 20 13 15 10 30 20 26 17 23 15 32 21 12 8 8.0 5.4

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Sensitive crops, such as pinto beans, cannot be managed profitably in saline soils. Table 4 shows the relative salt tolerance of field, forage, and vegetable crops. The table shows the approximate soil salt content (expressed as the electrical conductivity of a saturated paste extract (ECe) in dS/m at 25 degrees C) where 0, 10, 25, and 50 percent yield decreases may be expected. Actual yield reductions will vary depending upon the crop variety and the climatic conditions during the growing season. Fruit crops may show greater yield variation because a large number of rootstocks and varieties are available. Also, stage of plant growth has a bearing on salt tolerance. Plants are usually most sensitive to salt during the emergence and early seedling stages. Tolerance usually increases as the crop develops. The salt tolerance values apply only from the late seedling stage through maturity, during the period of most rapid plant growth. Crops in each class are generally ranked in order of decreasing salt tolerance.

5. USE OF SALINE WATER FOR CROP PRODUCTION Supplies of good quality irrigation water are expected to decrease in the future. Thus, irrigated agriculture faces the challenge of using less water, in many cases of poorer quality. The water having salinity and sodicity may require only minor modifications of existing irrigation and agronomic strategies in most cases, there will be some situations that require major changes in the crops grown, the method of water application, and the use of soil amendments. Use of saline water in agriculture requires the following principal changes from standard irrigation practices:

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i. ii. iii.

Selection of appropriate salt tolerant crops, Improvements in the water management, and in some cases, the adoption of advanced irrigation technology (such as drip, sprinkler, sub-irrigation); and Maintenance of soil physical properties to assure soil tilth and adequate soil permeability to meet crop water and leaching requirements.

Irrigation with saline water may cause some degree of salinization of the soil. This will cause a decrease in crop yield relative to yield under non-saline conditions. Relative yields decrease with increasing salinity of the irrigation water.

6. WATER MANAGEMENT IN SALINE SOILS 6.1. Management Strategies Water management strategies can be grouped into two: a) Demand side management, and b) Supply side management.

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Supply Side Management Supply management options may be defined as the actions that affect the quantity and quality of water at the entry point to the distribution system of a farm. Demand Side Management Demand management may be defined as the adaptation and implementation of a strategy by a water institution to influence the water demand and usage in order to meet any of the following objectives: economic efficiency, social development, social equity, environmental protection, sustainability of water supply and services and political acceptability. Demand management options include the actions that influence the use of water after the entry point. Demand side management is commonly implemented together with a water conservation program.

6.2. Water Supply Management Water supply management options include the following measures:

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i. ii. iii. iv. v.

Innovation/development of new supply source Harvesting rainwater at farm pond or canal Increase of usable water through mixing saline water with fresh water Increase of groundwater reserve through artificial recharge during monsoon Alternate use of saline and fresh water

Innovation /Development of New Source Of Supply In most natural saline zones, a relatively fresh-water aquifer underlains the saline shallow aquifer (Rashid, 2008; Asghar et al., 2002). If such an aquifer is found, it could be used as a source of irrigation supply. Other management practices may be needed along with irrigation, depending on the salinity level of the water and the salt tolerance of the desired crop. Harvesting Rainwater at Farm Pond or Canal During monsoon, the excess rain-water can be harvested at the excavated farm-pond or canal to cultivated dry-season crop, when the salinity is high and there is no source of freshwater. Ali and Rahman (2009b) found that 20 :1 ratio of land area to pond area is sufficient to cultivate low-water demanding dry-land crops (other than rice) in saline area.

Increase in Groundwater Reserve Through Surface Water Recharge by Recharge Well Through recharge tube-wells, excess rainwater during monsoon can be conveyed to aquifer. Large amount of water can be recharged through recharge well. As a result, the salinity of the aquifer water will be lower due to dilution and become within usable range. In flat topography, where aquifer with good transmissibility exists at shallow depth (in the first aquifer of 20-60 m depth), recharge structures with tubewell are often better choice than

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surface storage. Fig 2 illustrates the design of a recharge well. In principle, it is similar in construction to discharge well.

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Figure2. Schematic of a recharge well Mixing Saline Water with Fresh Water Irrigable water can be increased by mixing highly saline water with fresh water (good quality or low salinity water) to lower the salinity to acceptable/tolerable limit. Mixing does not reduce the total solute content, but reduce the solute concentration due to dilution. The salinity of the mixed water or the mixing ratio can be obtained by using the following equation (Adapted from Ayers and Westcot, 1985): Cm = (C1 × r1) + (C2 × r2 ) Where,

(1)

Cm = salt concentration of mixed water, mg/l C1 = salt concentration of first category of water, mg/l r1 = proportion of first category of water C1 = salt concentration of 2nd category of water r2 = proportion of 2nd category of water and, r1 + r2 = 1

Alternate Irrigation of Saline and Fresh Water Fresh and saline water can be applied at alternate sequence to increase irrigable water and to minimize salinity hazard. In such a practice, some sort of stress hardening of salinity stress also developes in plant.

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Irrigation with Saline Water at Less Sensitive Growth Stages As the fresh water is scarce, fresh water should be applied when it is essential. All growth stages of crops are not equally sensitive to salinity stress. Hence, irrigation with fresh water at sensitive stage(s) and irrigation with saline water (or a mix) at relatively insensitive stage(s) can facilitate optimum plant growth and yield. Irrigation Management Water management is the key to successful salinity management. Frequent light watering, using sub-surface drip or sprinklers, can help leach excess salts without allowing excess deep drainage to contribute water table problems. Irrigation management also impacts on nutrition of saline soil.

6.3. Water Demand Management

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In salt affected areas, demand of fresh water can be minimized or managed through the following principles:         

Saline water irrigation along with chemical amendment Controlling upward movement of salt Increasing leaching capacity developing / growing salt-tolerant crop variety providing optimum soil moisture at sowing/early stage Irrigating with saline water at less sensitive growth stages Irrigating at alternate furrows Drip or micro irrigation Saline irrigation and leaching

Saline Irrigation with Chemical Amendment Due to irrigation with saline water, salts are accumulated at the soil surface to such an extent that crop growth is restricted. Since sodium chloride is most often the dominant soluble salt, the SAR of the soil solution of saline soils is also high. Sometimes amendment (gypsum, elemental sulphur, or sulphuric acid application) is necessary for the reclamation of saltaffected soil depending on the practical importance. Chemical amendment neutralizes exchangeable Na and sodium carbonate. Leaching followed by amendment is needed for removal of salts derived from the reaction of the amendments. Reclamation by gypsum (Na+ is replaced by Ca++): Ca++ replaces the Na+ from the colloidal surface, and Na+ with SO4- - form Na2SO4 which is readily soluble in water and leach down or drain out from the field with irrigation water.

2NaX + CaSO4 = CaX + Na2SO4

(leaching to the soil system)

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In reclamation of saline-sodic soils, the leaching of excess soluble salts must be accompanied (or preceded) by the replacement of exchangeable sodium by calcium. If the excess salts are leached and calcium does not replace the exchangeable sodium, the soil will become sodic. Even non-irrigated sodic or saline-sodic soils show dramatic improvement with gypsum application.

Control of Upward Movement of Salts Crop residue at the soil surface reduces evaporative water losses, thereby limiting the upward movement of salt (from shallow, saline groundwater) into the root zone. Evaporation and thus, salt accumulation, tends to be greater in bare soils. Under crop residue, soils remain wetter, allowing fall or winter precipitation to be more effective in leaching salts, particularly from the surface soil-layers where damage to crop seedlings is most likely to occur. Plastic mulches used with drip irrigation effectively reduce salt concentration from evaporation.

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Increasing Leaching Capacity In the soils showing poor water-transmission property, addition of amendments like sand, rice- husk or rice-straw may be used to improve leaching under limited water availability. Presence of subsurface drains may also help in increasing the leaching of salts in silty clayloam soil. Incorporation of organic manure in the soil has two principal beneficial effects on saline soil: improvement of soil permeability and release of carbon dioxide and certain organic acids during decomposition. Growing Salt Tolerant Crop Variety There are some situations where it is either impossible or too costly to attain desirably low soil salinity levels, or to get fresh water. Under such circumstances, the only viable management option is to plant salt-tolerant crops. Thus, crop selection may be a good management tool for moderately water and soil salinity. Sensitive crops, such as pinto beans, cannot be managed profitably in saline soils. Determination of appropriate crops for irrigation should be done on the bases of the salt tolerance of the crop and the salinity of the irrigation water. Table 3 serves as a general guide of salt tolerance ratings for crops, realizing that management practices, irrigation water quality, environment, and crop variety also affect tolerance. Just as crops differ in tolerance to high salt concentrations, they also differ in their ability to withstand high sodium concentrations. Providing Optimum Soil Moisture at Sowing/Early Stage Most crop plants are more susceptible to salt injury during germination or in the early seedling stages. An early-season application of good quality water, designed to fill the root zone and leach salts from the upper 15 to 30 cm of soil, may provide good enough conditions for the crop to grow through its most injury-prone stages. Irrigation at Alternate Furrows Alternate furrow irrigation may be desired for single-row bed systems. This is accomplished by irrigating every other furrow and leaving alternating furrows dry. Salts are pushed across the bed from the irrigated side of the furrow to the dry side. Care is needed to

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ensure enough water is applied to wet all the way across the bed to prevent build up in the planted area.

Drip Irrigation In water scarce areas, the drip irrigation provides opportunities to enhance the use of saline waters, and even on saline soils. It results in considerable savings in irrigation water thus reducing the risks of secondary salinization. Sub-Surface Irrigation Sub-surface drip irrigation pushes salts to the edge of the soil wetting front, reducing harmful effects on seedlings and plant roots. Management of salt-affected soils requires a combination of agronomic practices depending on soil characteristics, water quality, and local conditions including climate, crops, economic, social, political and cultural environment, and existing farming systems. There is usually no single way to combat salt-problem in irrigated agriculture. However, several practices can be combined into an integrated system to achieve a satisfactory yield goal.

6.4. Other Management Practices

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Other management practices that could reduce the salinity hazard include:

Row / Seed Bed Manipulation In addition to leaching salt below the root zone, salts can also be moved to areas away from the primary root zone with certain crop bedding and surface irrigation systems. The goal is to ensure the zones of salt accumulation stay away from germinating seeds and plant roots. Double-row bed systems require uniform wetting toward the middle of the bed. This leaves the sides and shoulders of the bed relatively free from injurious levels of salinity. Without uniform applications of water (one furrow receiving more or less than another), salts accumulate closer to one side of the bed. Periodic leaching of salts down from the soil surface and below the root zone may still be required to ensure the beds are not eventually salted out. Optimum Fertilizer Application Well-adjusted fertilization could improve the yields of crops. There have been only a limited number of studies on the effect of salinity on the nutrition of crops in respect of micronutrients. A disturbed balance in the uptake and composition of major nutrients is bound to influence the plant composition of micronutrients. High salinity may interfere with the growth and activity of the soil‘s microbial population and thus indirectly affect the transformation of essential plant nutrients and their availability to plants. In saline soils, the availability of P is more a function of plant root length and area and the negative effect of excess chlorides on P absorption by roots. Application of judicious quantities of P-fertilizers in saline soils helps to improve crop yields by directly providing phosphorus and by decreasing the absorption of toxic elements like Cl. On moderately saline soils, the application of potassic fertilizers may increase the crop yields either by directly supplying K

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or by improving its balance with respect to Na, Ca and Mg. However, under high salinity condition, it is difficult to exclude Na effectively from the plant by use of K-fertilizers.

Control of Saline Water There are two areas of concern of saline soils; recharge and discharge areas. We should be realized that salinity is a water problem in most cases, not a soil problem. Excess water at the recharge area is what causes most salinity problems. Preventing the accumulation and resulting deep percolation of water to the bedrock is important. Excess water in recharge areas may arise as a result of man made ponding, excess accumulation of snow, excessive summer-fallowing, excess annual cropping, and decreased forage and perennial cropping. Control of water accumulation in recharge areas can be established by drainage. Care should be taken when attempting any type of drainage as it may result in causing salinity elsewhere. There are also different management strategies for saline discharge sites. The goal of discharge management should not be to remove salts completely, rather decrease the salt concentration in the top 12 inches of the soil. Practicing direct seeding in these areas reduces evaporation and increases deep percolation of water. This is achieved because the trash layer insulates the soil and consequently reduces evaporation. The trash layer also decreases water runoff which increases deep percolation. Removing Surface Salts The total salts and sodium must be reduced before plants can grow normally. The only effective way to reduce salts in soil is to remove them. Soils having a shallow watertable, or a highly impermeable profile; surface flushing of salts from soils that contain salt crusts at the surface may be practiced to ameliorate the saline soil.

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6.5. Pattern of Salinity and its Management: Case Study- Bangladesh 6.5.1. Land, Weather And Cropping Pattern Out of 9.03 million hectares of the cultivable area of the country, the coastal and offshore area is about 2.85 million hectares. The coastal zone is affected by varying degrees of salinity throughout the year, and the dry period (November – April) in particular, having high degrees of salinity (up to 24 dS/m). Factors contributing to salinity are inherent saline deposits, inundation of land by saline water or brackish tidal water during wet season, vertical rise of saline groundwater during dry season, and intrusion of saline tidal flow at lowlands. The availability of fresh water in that area is scarce. During dry period, the evaporation from soil surface takes place and the salt is left, hence accumulated on the surface over time. Weather, specifically the amount and distribution of rainfall, is contributing on the development of seasonal salinity. Long-term average of monthly total rainfall amount, salinity level of bare land and the canal water (connected to tidal flow of the sea) are pictured in Figure 3.

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Figure 3. Pattern of monthly rainfall and salinity level of bare soil and canal water at the saline area Transplanted Aman (T. aman) rice grown during the wet season (July-November) dominates the area as a mono-crop. Due to salinity problem, vast lands remain fallow during the dry season. The intensity of cropping in the saline zone is about 135 % (BBS, 2005), indicating potential for increasing crop production through technological intervention. Appropriate irrigation and water management practices along with other cultural practices could facilitate introducing additional crop during Rabi and/or Kharif season ( i.e. winter and early summer crop) in that area.

6.5.2. Farmers Management In the low-salinity affected areas, peoples are cultivating two crops, although yields are reduced to some extent. In the medium salinity affected areas, the farmers are growing only one crop, rice, during the rainy season, when the soil salinity becomes very low. In some years, when the rainfall is low, the rice fields in the highland are also affected by salinity. To avoid such salinity hazard, the farmers hold the rain water in the plot by making high bunds (levees) around the plot. During dry periods of the year (Dec.-Mar.), some farmers try to grow some winter crops (wheat, sesame, etc.) and Boro rice, with the water they stored in the ponds, located at the

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farm or close to their house. After using the limited stored water, they rely on natural rainfall. Sometimes they are successful (if early monsoon rainfall occurs), sometimes failed to grow crops due to lack of rainfall. Some farmers try to withdraw and use groundwater in addition to their pond-water. But due to high salinity of the groundwater, they are not successful with only groundwater. Some farmers use tactical strategies. Due to high iron content in the groundwater (saline), they withdraw the groundwater and left it on the ponds (within the pond water) for several days (2~3 days). When they feel that the iron has deposited at the bottom of the pond, they irrigate with that water. Actually, they used the mixing or blending method to reduce the salinity, although they are not aware of that technical term.

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6.5.3. Technological Intervention The researchers has developed /identified some salinity tolerant rice and wheat genotypes. The cultivars can tolerate medium salinity level – the wheat cultivars up to 12 dS/m salinity tolerance with moderate yield potential, one rice cultivar upto 6 dS/m and other two with up to 12 dS/m salinity tolerance. In addition, a deep aquifer with relatively fresh water (3~ 4 dS/m water salinity) underlying the shallow saline aquifer (12~ 20 dS/m water salinity) has been identified in several locations. This fresh aquifer is using as a source of irrigation to cultivate dry-season rice at a limited scale. But the researchers cautioned regarding the hydrologic balance of the area if large scale withdrawal of such groundwater continues for longer period. 6.5.4. Challenges Remaining Bangladesh, a country of about 160 million people, is striving to achieve self-sufficiency in food production. To achieve this, government policy is to utilize all available resources including intensive use of all cultivable area of the country for increasing agricultural production. The growth and development of crops depend on their genetic constitution and environmental conditions of soil, water and climate. Two types of factors limit the production in coastal saline zone of Bangladesh in specific, and in many coastal zones of the world in general. These are: hydro-geologic factor and (extreme) meteorological events (also called environmental constraints). Hydro-geologic condition throughout the coastal region of Bangladesh varies greatly from east to west and also from the distance of sea and height from the mean sea level. The technological solution in one location can not be directly applied in other locations. It needs verification, adaptation or modification. In addition, withdrawal of huge amount of groundwater may adversely affect the coastal hydrologic equilibrium.

6.6. Challenges of Water Management in Saline Areas Water management strategies adaptable to normal areas may not be applicable to saline areas. In saline areas, multiple factors (environment, soil type, subsurface geo-hydrology, drainability, depth to water-table, salinity of groundwater, etc.) affect the plant-water relation, availability of plant nutrient, and finally on crop growth and yield. Unavailability of some

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plant nutrients due to salinity effect and existence of some elements at toxicity level under saline condition are common. Different approaches of water management have been evolved for salt affected soils and also for saline water irrigation, but the benefit-cost ratio must be considered for their wide-spread adoption. The best method of water management must be cost-effective, sustainable, and environment friendly. Development of such a technology is a challenge to the researchers. In the future, adoption of water management technology in saline conditions will tentatively be governed by the economic factor rather than a technological means.

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REFERENCES Ali MH, Rahman MA (2009a) Study on the effect of different levels of saline water on wheat yield. In: Annual Report 2008-09. Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh. Ali MH, Rahman MA (2009b) Study of natural pond as a source of rain-water harvest and integrated salinity management under saline agriculture. In: Annual Report 2008-09. Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh. Asgar MN, Prathapar A, Shafique (2002) Extracting relatively fresh groundwater from aquifers underlain by salty groundwater. Agric. Water Manage. 52(2,3): 119-137 Ayers RS, Westcot DW (1985) Water quality for agriculture. FAO Irrigation and Drainage Paper 29 Rev.1, FAO, Rome, 174 p. Maas EV (1984) Salt tolerance of plants. In: The Handbook of Plant Science in Agriculture. B.R. Christie (ed.). CRC Press, Boca Raton, Florida. Maas EV, Hoffmann GJ (1977) Crop salt tolerance – current assessment. ASCE J. Irrig. and Drainage Div. 103(IR2):115-134 Richards LA.(1954) Diagnosis and improvement of saline and alkali soils. USDA Agricultural Handbook No.60, US Department of Agriculture, Washington D.C., 160 p. Rashid, MA (2008) Fresh water investigation for irrigation in coastal saline areas of Bangladesh. Proc. Paper meet 2008, Agril. Engg. Division, The Institution of Engineers, Bangladesh.

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Chapter 4

WATER DISINFECTION USING PERACETIC ACID M. M. Muñío1 and J. M. Poyatos2

1

Department of Chemical Engineering, University of Granada, Campus de Fuentenueva s/n., 18071 Granada, Spain 2 Department of Civil Engineering, University of Granada, Campus de Fuentenueva s/n., 18071 Granada, Spain

ABSTRACT

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Water disinfection consists in the deactivation, removal or killing of pathogens in order to avoid their growth and reproduction. If disinfection step is not carried out, diseases such as typhoid and paratyphoid enteric fevers, cholera, hepatitis and diarrhoea can alter human health. A lot of disinfection systems have been developed over the last years, but in general these systems should deactivate all pathogens in the water to be effective. An ideal one is able to provide long term disinfection to all water, safe, with minimum maintenance and economical. Although several methods comply with the conditions exposed above, chlorination is the most commonly used. But chlorine compounds reacts with a lot of substances present in water, as amino acids, ammonia, organic matter, iron, manganese and others. The result of such as reaction variety is an extensive range of disinfection by-products (DBPs) like trihalomethanes (THMs), haloacetic acids (HAAs), chlorophenols, haloketones and chloramines. These DBPs could cause human health problems, endanger aquatic life and stay in the environment for long periods. Some other chemical disinfectants (sodium hypochlorite, chlorine dioxide, hydrogen peroxide, bromine, peroxone, ozone, peracetic acid, etc.) and even physical treatments (ultraviolet light, gamma-rays, heat, sound, etc.) could be used to get disinfected water. Peracetic acid (PAA) is a mixture of acetic acid and hydrogen peroxide in watery solution. Its degradation products are non-toxic and can easily dissolve in water; it is a very powerful oxidant and the oxidation potential outranges that of chlorine and chlorine dioxide. This acid can be applied for the deactivation of a large variety of pathogenic microorganisms, spores and viruses. A great advantage is that its activity is hardly influenced by organic compounds that are present in the water. 

E-mail: [email protected]

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M. M. Muñío and J. M. Poyatos Nowadays PAA is applied for water purification as a disinfectant and it is suitable for cooling tower water disinfection where it controls Legionella bacteria. This chapter is about the use of peracetic acid as wastewater disinfectant. In general, PAA disinfection is applied to wastewater from secondary or biological treatment. Several factors have been analyzed: contact time and doses for different types of wastewater, effectiveness of the disinfection, combination with other treatments (as ultraviolet light), etc.

Keywords: wastewater, peracetic acid, disinfection.

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1. INTRODUCTION The availability of freshwater to meet different water needs has raised serious concerns in the last decades all around the world. Water scarcity, deterioration of quality and increasing demand has led to the development and use of alternative sources of water. Reclamation and recycling are now considered as key components of water and wastewater management policies around the world. [1]. Wastewater treatment plants (WWTPs) are complex systems, with different physicochemical and biological phenomena taking place simultaneously. Wastewater contains a number of chemicals compounds such as heavy metals, polyaromatic hydrocarbons, polar polycyclic organic chemicals (bisphenol A, phthalates and pharmaceutical and personal care products) and microorganisms. Wastewater collected from municipalities and communities must ultimately be returned to receiving waters or to the land, the most common disinfection method used in WWTPs is add chlorine, ozone or apply ultraviolet (UV) [2]. Chlorine is a powerful disinfectant against microorganisms [3]. Usually the bacterial are removed efficiently, although solid suspension could affect the disinfection capacity; however it is necessary a big amount of free chlorine for inactivate viruses and cyst [4]. There are some methods to increase the chlorination efficiency in wastewater, recently has been published a research where ultrasound has been applied to improve it [5], due to the ultrasound can break the microorganisms cellular membrane, improve the disintegration, improve the chlorine dispersion in the water and improve its diffusion in the cellules. Nevertheles, one of the mayor drawbacks of the use of chlorine is the formation of disinfection by-products (DBP), such as trihalomethanes, halogenated acetonitriles, cetones and aldehydes and phenols [2]. Ozone is a chemical agent extensively used in Europe for removal pathogen microorganisms in drinking water [6, 7]. There are some researches where ozonation has been used as wastewater treatment increasing the energetic costs and consequently the process cost [8], this increase of cost is more influenced by the presence of organic substances in the wastewater than by the presence of suspended solids [9]. Recently, the ozone has some relevance in the endocrine disruptors oxidation and has an optimal removal of Coliforms in wastewater [10]. Although there are some advantages, ozone presents some problems such as: influence of the solids suspended in the process efficiency, influence of the organic matter in the resistance of microorganisms, some subproducts are formed and there is a high energetic cost.

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The disinfection with ultraviolet (UV) system is other of the methods more used in wastewater due to its capacity for bacteria inactivation, viruses, spores and protozoan cysts [11]. This disinfection with UV has been used in industry wastewaters and in urban wastewater treated, and it is evident that it is much more efficient the use of UV systems in drinking water treatment due to the turbidity of wastewater treated is bigger, so the UV transmittance decreases [12]. By other hand, one of the problems of the UV technologies is the microorganism photo-reactivation; some microorganisms have the capacity for nucleic acid damage reparation [13]. The microorganisms‘ reactivation has been extensively studied and it has been closely related with the process temperature [14]. Due to the mentioned problems and the cost of operation, peracetic acid (PAA) is an alternative disinfection method to chlorination, ozonation or UV process, and it is known since the 1960s for its bactericidal, virucidal, fungicidal and sporicidal properties [15]. The aim of this chapter is to describe the properties and effect of PAA as water disinfectant.

2. USE OF PERACETIC ACID AS DISINFECTANT 2.1. Peracetic Acid Characteristics and Commercialization Peracetic acid (CH3COOOH) is a mixture of acetic acid and hydrogen peroxide in an aqueous solution with a low pH value (2.8). It is a colourless and bright liquid with no foaming capabilities and with an acrid (vinegar) odour. Peracetic acid can be produced by a reaction between hydrogen peroxide and acetic acid.

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CH3COOH  H 2O2   CH3COOOH  H 2O But oxidation of acetaldehyde also produces peracetic acid [16].  20 º C Acetaldehyde monoperacetate   CH 3COOH  CH 3CHO

Usually, PAA is produced in concentrations of 5-15%. When it is dissolved in water, it disintegrates to hydrogen peroxide and acetic acid, which finally split into basic molecules as water, oxygen and carbon dioxide. This acid is a very powerful oxidizing agent and as can be observed in Table 1 it has a stronger oxidation potential than chlorine or chlorine dioxide. Peracetic acid is considered a more potent biocide than hydrogen peroxide, being a sporicidal, bactericidal, virucidal and fungicidal at low concentrations ( 20 m 25 25

Figure 5. Granulometric classification for the raw materials according to Winckler diagram. 1 = common clay; 2 = sludge from WTP.

The prompt incorporation of WTP into red ceramics, however, must consider other factors. The high content of organic matter is a problem. Another factor is its high plasticity. In general, the sludges from WTP have high values of plastic limit. This can result in difficult in high shrinkage upon drying and formation of defects in the ceramic pieces. For these reasons, the additions of sludges from WTP to ceramic pastes used in the manufacture of red ceramic products should be moderate.

5.2. Evaluation of the Effects of the WTP Incorporation The quality of the ceramic pieces incorporated with sludge from WTP after firing at 1050 ºC, was determined through measurements of linear shrinkage, apparent density, water absorption and flexural strength. The pieces with 0-wt.% sludge addition (formulation EM0, 100 % common clay) fired at 1050 ºC were taken as reference.

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Figure 6. Linear shrinkage of the fired pieces as function of the addition of sludge from WTP.

Figure 7. Apparent density of the fired pieces as function of the addition of sludge from WTP.

The linear shrinkage of the ceramic pieces, shown in Figure 6, presented only slight variation within the dispersion limits, with the addition of the WTP sludge. This is a consequence of the chemical, physical and mineralogical similarities between the sludge and the clay used. The values of linear shrinkage of the pieces between 6.0 – 7.4 % indicate that at 1050 ºC the ceramic pieces sintered mostly by viscous flow. The apparent density of the ceramic pieces incorporated with sludge from WTP is shown in Figure 7. It can be observed that the apparent density (1.90 – 1.92 g.cm-3) is insensitive to the addition of the sludge. This is in accordance with the linear shrinkage values (Figure 6).

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Figure 8. Water absorption of the fired pieces as function of the addition of sludge from WTP.

Figure 9. SEM/BSE micrograph of fracture surface of fired pieces at 1050 ºC: sample EM0 (0-wt% Sludge).

Figure 8 shows the results of the water absorption of the fired ceramic pieces. Water absorption is related to the volume of the open pores in the structure. It is observed that the water absorption remains practically constant with sludge addition. Figures 9 and 10 show the fracture surfaces of sludge-free and 15%wt sludgeincorporated pieces fired at 1050°C. Open and isolated pores are indistinguishable. As expected, the microstructures of the sludge-free and sludge-incorporated pieces are very

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similar. This result is very interesting, because clearly shows that the incorporation of sludge from WTP to a common clay in moderate amounts provoke only slight changes on the texture and porosity of the red ceramic products.

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Figure 10. SEM/BSE micrograph of fracture surface of fired pieces at 1050 ºC: sample EM15 (15-wt% sludge).

Figure 11. Flexural strength of the fired pieces as function of the addition of sludge from WTP.

The flexural strength of the ceramic pieces incorporated with sludge from WTP is shown in Figure 11. As can be observed, the flexural strength also presents a slight variation with the sludge addition, like the linear shrinkage and apparent density. Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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Figure 12. Weibull diagram for the formulation EM0 fired at 1050 ºC.

Figure 13. Weibull diagram for the formulation EM5 fired at 1050 ºC.

The Weibull approach was used to analyze the flexural strength data of the ceramic pieces fired at 1050 ºC as shown in Figures 12 - 15. Typical Weibull plots (ln.ln (1 / (1-F)) versus ln tension) representing the flexural strength data were used to determine the Weibull modulus (shape parameter) and the characteristic strength (at which the probability of failure is 63.2 %) of the pieces. The value of maximum rupture strength for each formulation was also determined. These values are summarized in Table 10. The correlation coefficients obtained by means of linear regression present values around 1. This indicates that the experimental flexural strength data of the ceramic pieces containing sludge from WTP fit well the Weibull distribution. It must be noticed that these Weibull distribution parameters are valid for the specific used testing conditions.

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Figure 14. Weibull diagram for the formulation EM10 fired at 1050 ºC.

Figure 15. Weibull diagram for the formulation EM15 fired at 1050 ºC.

If the testing conditions are altered, for example to samples collected from an industrial production flow line and proved under other procedure, the Weibull parameters will certainly differ. The values of the Weibull modulus in the range of 4.4 to 9.4 are within the usual range for clay ceramics [35]. It can also be noticed that the Weibull modulus increased up to 10 wt-% sludge additions, and decreased with 15 wt-% sludge addition. The highest value of the Weibull modulus was found for the pieces of the EM10 formulation. This result may be related to the better homogeneity of the structure of these pieces. On the other hand, it can be observed that there

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is no obvious influence of the WTP sludge additions on the characteristic strength and maximum rupture strength of the ceramic pieces. Table 10. Weibull analysis of flexural strength data of the pieces fired at 1050 ºC Formulation LC EM0 0.98609 EM5 0.99407 EM10 0.98854 EM15 0.98726 LC = linear correlation coefficient; WM = maximum rupture strength.

WM o (MPa) max (MPa) 4.4 16.54 23.37 6.8 19.44 23.63 9.4 15.58 19.26 6.1 19.19 23.04 Weibull modulus; o = characteristic strength; max =

In Brazil, the tolerated values of water absorption (wa) and mechanical strength () for industrial production of red ceramic products are: dense bricks (wa < 22 % and   2.0 MPa), ceramic blocks (wa < 22 % and   5.5 MPa), roofing tiles (wa < 18 % and   6.5 MPa). As can be observed in Figure 8 (water absorption data) and Figure 11 (flexural strength data), all ceramic pieces incorporated with sludge from WTP fired at 1050 ºC presented optimal values of water absorption and mechanical strength for red ceramic industrial production.

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5.3. Environmental Evaluation The potential environmental hazard represented by the pure WTP sludge and by the sludge-incorporated ceramic product (formulation EM15 fired at 1050°C) was evaluated through chemical leaching and solubilization tests according to Brazilian regulations. Tables 11 and 12 show the results of the leaching and solubilization tests. The reference values of the Brazilian regulation are also shown [11]. It can be seen in Table 11 that the concentration of silver, arsenic, barium, cadmium, total chromium and lead in the leachate are below the maximum limits accepted by the Brazilain regulation. Thus, these samples could be classified as non-hazardous solid waste materials. The solubilization data for the samples are given in Table 12. The results highlight that for the WTP sludge the concentration barium (0.97 mg.L-1), iron (2.59 mg.L-1), manganese (0.39 mg.L-1) and lead (0.06 mg.L-1) exceed the limits admitted by the regulation. Thus, this sludge from WTP can be classified as a non-inert waste material (class IIA). This result is important. It indicates clearly that the careless disposal of this sludge in the environment should be avoided. The solubilization test of the sample EM15 fired at 1050 ºC showed different results. It exhibits higher chemical resistance against solubilization. The concentration values are much smaller than those for the pure WTP sludge and within the ranges established by the Brazilian regulation. This is likely caused by the encapsulation of the elements in the vitreous phase that is formed above 1000°C in the structure. The fired sample of the EM15 formulation is classified as an inert material (class IIB). Therefore, there is no risk in relation to incorporation of the sludge from WTP in red ceramic products.

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Table 11. Results of the leaching test for the investigated samples (mg.L-1) Element Ag As Ba Cd Cr (total) Pb

Sludge from WTP < 0.01 < 0.01 0.100 < 0.001 0.03 0.04

Formulation EM15 < 0.01 < 0.01 0.06 < 0.001 < 0.01 0.07

Regulatory Level 5.0 1.0 70.0 0.5 5.0 1.0

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Table 12. Results of the solubilization test for the investigated samples (mg.L-1) Element Ag Al As Ba Cd Cr (total) Cu Fe Mn Pb Zn Hardness Nitrates Sulfates Surfactants

Sludge from WTP 0.01 0.07 < 0.01 0.97 < 0.01 0.02 0.02 2.59 0.39 0.06 0.02 180 < 0.01 45 < 0.20

Formulation EM15 < 0.01 0.04 < 0.01 0.08 < 0.01 0.01 0.03 0.23 0.07 0.01 0.03 100 < 0.01 34 < 0.20

Regulatory Level 0.05 0.20 0.01 0.70 0.005 0.05 2.0 0.30 0.10 0.01 5.0 500 10.0 250.0 0.50

CONCLUSION In this chapter the recycling of sludge from WTP as an alternative raw material in clayey formulations used in the manufacture of red ceramic products was investigated. The results showed that the chemical and mineralogical compositions of the WTP sludge are very similar to those of the common clay in which it is going to be incorporated. Experiments of incorporation have confirmed what the incorporation of up to 15 wt-% of sludge from WTP, allows red ceramic products (dense bricks, ceramic blocks and roofing tiles) for civil construction with good physical and mechanical characteristics to be produced. Furthermore, leaching and solubilization tests indicated that the red ceramic pieces fired at 1050 ºC do not represent any hazard to the environment. This result make the incorporation of the WTP sludge into red ceramic products a potentially interesting way to recycle this waste.

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REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

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[15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27]

Toffler, A. A terceira onda. 25th ed.; Record: São Paulo, SP, 2001. Richter, C.A. Tratamento de água: tecnologia atualizada. 2nd ed.; Edgard Blücher: São Paulo, SP, 1991. Davis, M.L.; Cornwell, D.A. Introduction to environmental engineering. 3rd ed.; McGraw-Hill: USA, 1998. Oliveira, E.M.S. Thesis Ph.D, UENF-PPGECM, Campos dos Goytacazes, RJ, 2004. Januário, G.F.; Ferreira Filho, S.S. Eng. Sanit. Ambient. 2007, 12, 117-126. Santos, P.S. Ciência e tecnologia de argilas, 2nd ed. Edgard Blücher: São Paulo, SP, 1989, Vol. 1. Perez, J.A.; Terradas, R.; Manent, M.R.; Seijas, M.; Martinez, S. Ind. Ceram. 1996, 16, 6-8. Dondi, M.; Marsigli, M.; Fabbri, B. Tile and Brick Int. 1997, 13, 218-225. Menezes, R.R.; Neves, G.A.; Ferreira, H.C. Rev. Bra. Eng. Agrí. Amb. 2002, 6, 303313. Segadães, A.M. Adv. Appl. Ceram. 2006, 105, 46-54. Brazilian Standard NBR – 10004, Solid Wastes: Classification, ABNT: Rio de Janeiro, RJ, 2004. Souza, G.P.; Sánchez, R.; Holanda, J.N.F. Cerâmica. 2002, 42, 102-107. Carretero, M.I.; Dondi, M.; Fabbri, B.; Raimondo, M. Appl. Clay Sci. 2002, 20, 301306. Bauluz, B.; Mayayo, M.J.; Fernandez-Nieto, C.; Cultrone, G.; López, J.M.G. Appl. Clay Sci. 2003, 24, 121-126. Khalfaoui, A.; Hajjaji, M. Appl. Clay Sci. 2009, 45, 83-89. Souza, G.P.; Rambaldi, E.; Tucci, A.; Espósito, L.; Lee, W.E. J. Am. Ceram. Soc. 2004, 87, 1959-1966. Olgun, A.; Erdogan, Y.; Ayhan, Y.; Zeybek, B. Ceram Int. 2005, 31, 153-158. Moreira, J.M.S.; Manhães, J.P.V.T.; Holanda, J.N.F. J. Mater. Proc. Tech. 2008, 196, 88-93. Monteiro, R.C.C.; Figueiredo, C.F.; Alendouro, M.S.; Ferro, M.C.; Davin, E.J.R.; Fernandes, M.H.V. Waste Manag. 2008, 28, 1119-1125. Freire, M.N.; Souza, S.J.G.; Holanda, J.N.F. Waste Resor. Manag. 2008, 161, 23-27. John, V.M.; Zordan, S.E. Waste Manag. 2001, 21, 213-219. Dominguez, E.A.; Ullmann, R. Appl. Clay Sci. 1996, 11, 237-249. Lemeshev, V.G.; Gubin, I.K.; Salelev, Y.A.; Tumanov, D.V.; Lemeshev, D.O. Glass Ceram. 2004, 61, 308-311. Teixeira, S.R.; Souza, A.E.; Santos, G.T.A.; Pena, A.F.V. J. Am. Ceram. Soc. 2008, 91, 1883-1887. Morete, G.F.; Paranhos, R.P.R.; Holanda, J.N.F. Soldagem Insp. 2006, 11, 141-146. Pantikes, Y.; Angelopoulos, G.N. Adv. Appl. Ceram. 2009, 108, 50-56. Andreoli, C.V.; Pegorini, E.S.; Hoppen, C.; Tamarini, C.R.; Neves, P.S. Produção, composição e constituição de lodo de tratamento de água (ETA), Projeto PROSAB/ABS: Rio de Janeiro, 2006.

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[28] JCPDS Cards: kaolinite: 14-164; quartz: 46-1045; gibbsite; 33-18; muscovite: 6-263; microcline: 19-926; goethite: 29-713. [29] Brazilian Standard NBR – 7181, Soil: Granulometric Analysis, ABNT: Rio de Janeiro, RJ, 1984. [30] Matsuo, Y.; Kimura, S. Techno Japan. 1988, 21, 8-19. [31] Quinn, G.D. Strength and proof testing, Engineering Materials Handbook: Ceramics and Glass, ASM International: New York, 1992, Vol. 4. [32] Brazilian Standard NBR – 10005, Solid Wastes: Leaching Test, ABNT: Rio de Janeiro, RJ, 2004. [33] Brazilian Standard NBR – 10006, Solid Wastes: Solubilization Test, ABNT: Rio de Janeiro, RJ, 2004. [34] Pracidelli, S.; Melchiades, F.G. Cerâmica Ind. 1997, 2, 31-36. [35] Zanotto, E.D.; Migliori Jr., A.R. Cerâmica. 1991, 37, 11.

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In: Water Recycling and Water Management Editor: Daniel M. Carrey

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Chapter 11

WATER AND INTERNATIONAL TRADE LAW: FRIENDS OR FOES? Vasiliki-Maria Tzatzaki* University of Athens, Athens, Greece

ABSTRACT

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A few years ago, water and international trade law barely knew each other. Water is a vital source for life, taken for granted and overexploited. International trade law is expanding, ignoring borders and nationalities. However, water scarcity, due to climate change and population growth, became the connecting link between water and international trade law. International trade on water, regardless of whether it is bottled or bulk, is a reality and raises questions of its regulation. Can water be a commodity? Which rules are applicable to water imports or exports? The aforementioned are some of the questions that this paper is addresses. In particular, it argues that water is certainly a product in its bottled form and therefore, is subject to the rules of international trade. Moreover, it deals with bulk water trade and further supports that, despite the debate, bulk water should also be considered a commodity, when transferred. Finally, as for the future perspectives, the issue of virtual water is considered. These issues are examined within the legal framework provided by the World Trade Organization, aiming at highlighting the ‗friendship‘ between water and international trade law. ―Water, thou hast no taste, no color, no odor; canst not be defined, art relished while ever mysterious. Not necessary to life, but rather life itself, thou fillest us with a gratification that exceeds the delight of the senses.‖ Antoine de Saint-Exupery, Wind, Sand, and Stars, 1939.

*

The author would like to gratefully acknowledge the contribution of Vassiliki Karzis, University of Athens.

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INTRODUCTION Water is life. Our bodies consist of water and we cannot survive without it. Day by day the population of the planet is increasing, which involves the increase of water demand. Water has multiple uses and satisfies many basic human needs such as sanitation, consumption, means of communication etc. In order for the aforementioned human needs to be satisfied, freshwater resources are being overexploited and depleted. Water, in its theoretical context, seizes to be just one of the four natural elements and becomes a multifaceted element with many values. Hence, it has cultural, ecological, social, political and economic dimensions. This paper focuses on the legal framework governing the international trade of water. In other words, it examines whether water is a commodity and therefore, the application of the rules of international trade law. The analysis does not deal with the advantages and disadvantages of considering water as a commercial good but focuses strictly upon the commodification of water. Moreover, the analysis is based on the fact that there is no explicit legal framework governing international trade of water, attempting to apply the already existing rules of the World Trade Organization in the transboundary movement of water as a commodity. For methodological reasons, the present paper is divided in three parts, according to the forms of water in international trade: trade of bottled water, bulk water imports and exports and last but not least, virtual water. Each of the three forms of water is examined two fold: first, the question whether water in each specific form is commodity is answered and secondly, the existing international trade rules that could apply are proposed. Despite the fact that state practice and jurisprudence are also mentioned, the question of whether water is a commodity is far from being easy to answer. This paper argues that water trade is increasing and the lack of an international legal framework aggravates the problems of water regulation.

1. BOTTLED WATER AS A COMMERCIAL COMMODITY Bottling water [1] is the most common way of commercialising this good [2]. The past few years, mainly due to health and sanitary reasons, consumers have shown their preference for bottled water, whilst expressing their insecurity for tap water consumption [3]. The ―battle‖ against bottled water focuses on the consequences of its consumption on the environment [4]. On the one hand, manufacturing and recycling water bottles demands huge amounts of energy [5], while simultaneously it constitutes a source of water and air pollution. On the other hand, the transportation of water, both domestically and transboundary, leads to power and fuel consumption [6]. It is worth noting that the extraction of water from aquifers has, from time to time, triggered the reaction of local communities [7]. Consequently, the consumption of bottled water amounts to environmental risks in general and, especially, to overexploitation of freshwater natural resources, a problem that is becoming even more serious in countries suffering from water deficit. The commerciality of bottled water is verified by the Agreement on Technical Barriers to Trade [8]. The states have the obligation to notify on the technical and sanitary regulations and standards that apply to bottled water [9]. Furthermore, Canada and the USA have agreed

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on the commerciality of bottled water and its exportation in this form by the first country to the second [10]. Finally, bottled water is considered a commercial commodity by the Harmonised System Codes [11]. Even though bottled water is not referred to as a commodity by the General Agreement on Tariffs and Trade (hereinafter GATT) [12], this can be derived from the definition of the term ‗primary products‘ [13]. Moreover, some scholars support that, since it is not explicitly excluded by the GATT, water as a commercial commodity falls within its regulatory framework [14]. The same argument supporting the commerciality of bottled water is also used when examining the regulations of the North American Free Trade Agreement (hereinafter NAFTA) [15]. According to the aforementioned, water in bottles is a product and consequently, follows the rules regulating international trade. International trade law and more specifically the law of the World Trade Organization, aim at facilitating the movement of goods through the abolition of governmental barriers and limits [16]. Since it is accepted that bottled water constitutes a commodity, the rules of the World Trade Organization establish a threshold to the governmental capacity of limiting its sales and exports. According to the NAFTA and GATT, barriers to the export of products and goods are banned, with a few exceptions –namely, GATT article XI, 2 (a). Specifically, States cannot set:

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―(...) prohibitions or restrictions other than duties, taxes or other charges, whether made effective through quotas, import or export licenses or other measures (…) on the exportation or sale for export of any product destined for the territory of another [state]. [17]‖

The above prohibition also applies to any State restrictions to imports and exports of bottled water. However, notwithstanding the explicit prohibition [18], both the NAFTA and GATT, allow States to exceptionally impose restrictions for environmental purposes [19] that are linked to the protection and preservation of exhaustible natural resources [20]. A question that arises at this point is to what limit are freshwater resources ‗exhaustible‘. Hence, do they fall within the scope of the NAFTA and GATT? Some may support that the term ‗exhaustible natural resources‘ does not include freshwater resources, since they are renewable, due to the water cycle [21]. Before examining whether freshwater is ‗exhaustible‘ or ‗renewable‘ resources from a legal point of view, it is important to refer to certain underground springs. Water cycle, which actually renders water a renewable resource, does not apply to all cases of water resources. For example, confined aquifers cannot be renewed and thus, constitute indeed an ‗exhaustible‘ natural resource [22]. The United Nations‘ International Law Commission decided to examine the aforementioned resources through a separate Resolution [23] which defines that confined groundwater: ―(...) is groundwater not related to an international watercourse (...)‖ [24].

On the other hand, natural water resources, especially underground, or in arid or semiarid areas of the planet, are also ‗exhaustible‘ rather than ‗renewable‘ resources. In other words, natural water resources can morphologically differ from each other, in such a way that some are surface, others are underground and some interlock while others don‘t. These morphological differences do not imply that a separate legal regulation should be adopted for every type of water resource, since this would lead to the fragmentation of the already

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existing regulatory framework. According to the aforementioned, in combination with the intense water famine in several areas of the world, natural water resources could fall within the ambit of the term ‗exhaustible‘ under the GATT and NAFTA. In fact, the jurisprudence of the World Trade Organisation has interpreted broadly the term ‗exhaustible natural resources‘, including fresh air [25] and sea turtles. Namely, in the Shrimp-Turtle [26] case, the Appellate Body of the World Trade Organization adopted an evolutionary interpretation of the term. Promoting the achievement of sustainable development [27] and reiterating the Advisory Opinion of the International Court of Justice in the Namibia [28] case, the Appellate Body found that the term ‗exhaustible natural resources‘ is not static but evolutionary. Based on the textual interpretation, the Appellate Body decided that the term ‗exhaustible resources‘ does not exclude the renewable resources [29]. The Appellate Body‘s approach to the term ‗exhaustible natural resources‘ indicates its support to environmental positions, promoting at the same time a flexible relationship between environment and trade [30]. This environment-friendly approach of the Appellate Body reinforces the argument that freshwater resources could be considered as ‗exhaustible natural resources‘ according to international trade law. In conclusion, within the framework of international trade law, bottled water is a commodity, subject to it rules and regulations. States have the ability to regulate and limit the consumption and export of bottled water to the extent that it is necessary for the preservation of natural water resources within their domain. The above limits should not be treated as barriers to the application of proper state-policies concerning water regulation. On the contrary, the restrictions set by international trade law oblige States to regulate the market of bottled water according to the notion of sustainable development and the necessity to protect and preserve freshwater resources.

2. BULK WATER TRADE Contrary to water in bottles, questions arise as to whether water can be tradable in its bulk form. The international trade of bulk water can take place either between states [31], or between a State and a private company [32], or finally, between two private companies of different nationalities [33]. Furthermore, bulk water exports [34] can take many forms, some less and some more expensive. In particular, it can be carried out by pipes, by large scale diversions or by super tankers. The particular nature of water, the socioeconomic consequences resulting from its commodification, as well as the aforementioned forms of bulk water exports render the general matter even more complex, both from a legal, as well as from a technical point of view. For methodological reasons, the current section is divided in two parts: the first part examines the methods used for the export of bulk water along with state practice, while the second part attempts to define whether bulk water is a commodity and consequently, whether it is regulated by rules of international trade law.

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Methods for Trading Bulk Water Water diversion from transboundary freshwater resources [35] is the first method of bulk water trade. From a technical point of view, the diversion of water in an natural resource does not equal to international trade. It equals to the alteration of the flow of water resources in general, including the construction of dams [36], so as the water can flow in a specific direction. From a legal point of view, the diversion can cause disputes due to emerging technical difficulties, as well as the lack of a specific regulatory framework. For example, in the Bayview case [37], Texan farmers claimed that the surface waters of the Rio Grande River have become a commodity, because the river is deprived of its natural flow, due to large scale diversions, in order for the USA and Mexico to control its flow. According to their arguments, this provides them with property rights and makes them investors on the other side of the border. On the contrary, Mexico argued that there is no foreign investment giving rise to a dispute. The tribunal adopted the latter opinion and ruled in favour of Mexico, highlighting that the applicants didn‘t have property rights equivalent to a foreign investment, as defined in the NAFTA [38]. However, the most common form of international trade of bulk water is its export or import through pipelines [39]. For example, Turkey is abundant in natural freshwater resources [40], in contrast to the other semi-arid countries of the region [41]. Until recently the Turkish governments have made efforts to use this privilege and provide, at the same time, the country with a strategic advantage in the unstable region of the Middle East [42]. The outmost ambitious project by Turkey to commercialise its rich water reserves was the so called ―Peace Pipes‖ [43]. In the end this plan failed, mostly due to Gulf States‘ refusal to participate and to fund it due to political reasons [44]. Moreover, in the region of Great Lakes on the Canadian-American border, various plans for the construction of water pipelines from the Lakes to American states suffering from water famine were put forward. One of the largest proposals was the Multinational Resources Proposal -a Canadian-American consortium- that would proceed with the diversion of the North Thompson River waters towards the Colombia River, landing up in a pipeline to California [45]. The last method, and perhaps the most attainable, of international trade of bulk water is its transport in super tankers. Private companies have applied for licences to exploit the region of the Great Lakes for the export, distillation and sale of water to countries with water famine problems by super tankers [46]. Furthermore, after the failure of the ―Peace Pipes‖ project, the Prime Minister of the country, Mr. Turgut Özal, suggested the extraction of bulk water from the Manavgat River and its distribution to countries with shortage, such as Jordan, Israel and Greece [47]. Finally, super tankers were used by Greece in order to deliver water to Cyprus in 2008 [48].

Bulk Water in International Trade Law To what extent bulk water, irrespective of the way it is traded, constitutes a commodity regulated by rules of international trade law is a much disputed subject. On the one hand, it is supported that water, when transported in tankers, is a commodity, given the fact that nothing, except its quantity, distinguishes it from bottled water [49]. On the other hand, it is supported

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that bulk water does not constitute a commodity [50]. In international trade law, neither of the two aforementioned opinions prevails over the other. Consequently, the fact that the question as to whether bulk water is a product has no definite answer and the absence of specific provisions or relevant jurisprudence, make it difficult to say with certainty whether that the GATT rules apply to bulk water trade. Notwithstanding the special nature of water, as well as the need of States to maintain the control, use and protection of their natural resources [51], the exclusion of bulk water trade from the regulatory framework of international trade law would be a source of future problems. Its exclusion from the GATT simply postpones its future integration [52]. According to the author, in case of a dispute before the World Trade Organization panels, it is more likely that the judicial organs will conclude that the trade of bulk water does fall under the GATT regulations. According to Article I of the GATT:

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―With respect to customs duties and charges of any kind imposed on or in connection with importation or exportation or imposed on the international transfer of payments for imports or exports, and with respect to the method of levying such duties and charges, and with respect to all rules and formalities in connection with importation and exportation, and with respect to all matters referred to in paragraphs 2 and 4 of Article III, any advantage, favour, privilege or immunity granted by any contracting party to any product originating in or destined for any other country shall be accorded immediately and unconditionally to the like product originating in or destined for the territories of all other contracting parties‖ [53].

According to the wording of the above article, in the case where a State imports bulk water from one or more States or, respectively, exports, the governments shall not discriminate, as to the privileges granted, between ―receivers‖ or ―senders‖ and local commissionaires of bulk water [54]. Furthermore, article III contains the national treatment rule, according to which: ―The contracting parties recognize that internal taxes and other internal charges, and laws, regulations and requirements affecting the internal sale, offering for sale, purchase, transportation, distribution or use of products, and internal quantitative regulations requiring the mixture, processing or use of products in specified amounts or proportions, should not be applied to imported or domestic products so as to afford protection to domestic production‖ [55].

According to the previous article, member States of the GATT shall not treat imported products and goods in a discretionary manner as far as their production and consumption is concerned. This rule would be applicable in circumstances of States wishing to limit the import of bulk water, for instance, for environmental reasons. Finally, if bulk water is considered a commodity, then the first two paragraphs of article XI of the GATT are applicable. This article, in paragraph 1 sets the basic rule of import and export restrictions. According to the wording of this regulation: ―No prohibitions or restrictions other than duties, taxes or other charges, whether made effective through quotas, import or export licences or other measures, shall be instituted or maintained by any contracting party on the importation of any product of the territory of any

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other contracting party or on the exportation or sale for export of any product destined for the territory of any other contracting party‖ [56]. This rule is very important for the trade of bulk water, since it can limit the ability of member States of the WTO to adopt policies and national legislations that might prohibit the trade of bulk water. Moreover, issues arise as to whether this provision extends to certain transactions of bulk water that have already begun, or if it extends only to future transactions amongst members of the WTO [57]. The second paragraph of article XI contains an exception to the above general prohibition: ―(...) prohibitions or restrictions temporarily applied to prevent or relieve critical shortages of foodstuffs or other products essential to the exporting contracting party‖ [58].

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According to the above provision, when a State prohibits the import or export of bulk water it violates article XI, unless the prohibition falls under the exception of the second paragraph of the same article. An exception that would justify the prohibition of the import or export of bulk water on behalf of a State has to be temporary [59] and it has to aim at the prevention or relief of crucial food shortages [60] or other products essential to the exporting State [61]. For example, if the shortages are not crucial then they do not fall under the exception of paragraph 2 (a) article XI of the GATT, while restrictions based on State policies for the protection of the environment are not included in the exception, since they are of a permanent character. While article XI paragraph 2 (a) provides an exception only to the rule of the first paragraph of the article, article XX provides an exception to the provisions of article XI as well as articles I and III. Article XX allows member States to derive from the regulations of the GATT in order to protect certain interests. In the case of bulk water trade the paragraphs of article XX that apply are the following: ―Subject to the requirement that such measures are not applied in a manner which would constitute a means of arbitrary or unjustifiable discrimination between countries where the same conditions prevail, or a disguised restriction on international trade, nothing in this Agreement shall be construed to prevent the adoption or enforcement by any contracting party of measures: (...) (b) necessary to protect human, animal or plant life or health; (...) (g) relating to the conservation of exhaustible natural resources if such measures are made effective in conjunction with restrictions on domestic production or consumption; (...)‖ [62].

Prohibitions and restrictions concerning imports and exports of products can be justified in light of article XX (b). For imports and exports of bulk water this specific article applies only in such circumstances where the protection of humans, animals or plants or of their health is necessary. Moreover, prohibitions of bulk water imports or exports could be considered justifiable through favourable agricultural measures only if the agriculture is cohesively linked to nutrition, both for humans as well as for animals. According to article XX (g), in order for an import or export restriction to be justified two prerequisites have to be conjunctively satisfied: first, the measures adopted have to be intended for the maintenance of an ‗exhaustible natural resource‘ and second, together with

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these measures, the States have to restrict the domestic production or consumption. Bulk water, as argued earlier, is an ‗exhaustible resource‘. In order for a State restriction to fall under the exception of article XX (g), the State has to set, for example, restrictions against the removal of water from the natural resource or its loading for transport. This is exactly what was decided by the USA Supreme Court in the Sporhase v. Nebraska [63] case. In this case the Court found that the State is forbidden from taking measures that restrict the transport of bulk water from underground waters. According to the Court, in order for such measures to be exceptional, they have to be aimed at the preservation of underground waters and should also set a threshold for their use within the State [64]. Even though the Supreme Court based its decision on a national legislation clause [65], this decision, however, sets a precedent and can be applied mutatis mutandis in case of a similar dispute on bulk water trade on a transboundary level, regulated by GATT rules. Even if the prerequisites of the exceptions of paragraphs (b) and (g) of article XX are satisfied, a State‘s restriction has to satisfy the prerequisites of the article‘s chapeau, as well [66]. According to Brown Weiss, for the export of bulk water, the wording of the chapeau of article XX ―where the same conditions prevail‖ is of particular importance. Since ecosystems are inherently different from each other, it is impossible for ―the same conditions to prevail‖ in ecosystems of different countries. Therefore, the measures that restrict exports so as to protect the ecosystems cannot be justified where ―the same conditions prevail‖, something highly unlikely in this instance [67]. Based on the aforementioned, the regulations of international trade law, and especially of the GATT, are applied to bulk water trade, provided that bulk water falls within the meaning of commodity.

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3. VIRTUAL WATER AND INTERNATIONAL TRADE LAW Virtual is the water included in a product [68]. In other words, virtual water is the water consumed during the production process of a product [69]. Virtual water is the link between water, food and commerce. Furthermore, virtual water is a successful tool for balancing water deficiencies suffered by States [70]. The trade of virtual water constitutes exercise of comparative advantage [71], since the States, which are in the need of water, choose not to import water as a commodity, but prefer to import products which include the otherwise imported water in their production process [72]. Virtual water allows for a better world-scale distribution of fresh water natural resources [73]. According to Pascal Lamy, Director General of the World Trade Organization, some products containing water will be included in the Doha Round, which indicates the effort of States to combine free trade and environmental protection, as well as to ensure the joint harmonious function of these two international law regimes [74]. Virtual water trade has several important advantages, mainly for countries located in areas of the planet suffering from serious drought problems [75]. Firstly, virtual water is important from a political point of view, since it helps political leaders deal with any possible water shortage of their country. Moreover, the trade of virtual water offers financial solutions. For example, virtual water contained in crops can be sold at a price lower than that of the water necessary for the cultivation of the crops, providing to those countries that import virtual water by importing crops with a double advantage: first, they import the water

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necessary for the cultivation of crops and secondly, they purchase it at a lower price than the price they would have paid for importing the water for the cultivation of crops [76]. Finally, by offering solutions both on a political as well as financial level, and contributing to security issues, virtual water can prevent wars and conflicts over water [77]. The fact that virtual water is a commodity is strengthened by the Dublin Principles and, specifically, Principle 4, according to this principle: ―Water has an economic value in all its competing uses and should be recognized as an economic good‖ [78].

The aforementioned indicate that virtual water is a commodity. However, there is no indication as to what rules regulate its trade. Which already existing rules of the World Trade Organization could be applied to virtual water trade? Since virtual water is water contained in products, and mainly in agricultural products, the most relevant legal framework for the regulation of virtual water trade is the Agreement on Agriculture [79]. The Preamble of the Agreement on Agriculture states:

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―(…) [C]ommitments under the reform programme should be made in an equitable way among all Members, having regard to non-trade concerns, including food security and the need to protect the environment; having regard to the agreement that special and differential treatment for developing countries is an integral element of the negotiations, and taking into account the possible negative effects of the implementation of the reform programme on leastdeveloped and net food importing developing countries‖ [80].

Despite the wording of the above paragraph of the Preamble, where emphasis is added to the different treatment between developing and developed countries, it is not clear whether the diversity in treatment entails a consideration of the differences between State parties as for their water needs. One positive fact is that issues directly relevant to water, like the protection of the environment and food safety, have been included in negotiations of the Doha Round. This implies that the tariff levels and the minimum trade access will be conditioned on natural water resource preservation requirements. The outcome according to Mori will be the significant import increase of products containing water in countries tackling water famine [81]. Therefore, the pre-existing rules of the Agreement on Agriculture could play an important part in the efficient reduction or eradication of agricultural substitutes that promote, for instance, the development of crops in areas with water shortages. In order for this to be achieved, the World Trade Organization should allow issues other than commercial, such as the protection and the management of fresh water natural resources, to be taken into consideration.

CONCLUSION The lack of an international legal framework, as well as jurisprudence, causes problems as to whether water is a commodity. According to this paper, the examination of the issue should start from the basis that water in trade can take various forms. Either bottled, or bulk or virtual, water can be considered a commodity and traded between countries. The already

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existing rules of the World Trade Organization, when adopted, did not take into consideration the particular characteristics of water and its importance for humans. However, they are sufficient to be the first step towards the regulation of international trade on water. Bottled water is undisputedly a commercial good and the law of the World Trade Organization can regulate its international trade, providing member states with equal opportunities and consumers with reasonable prices. The case is not the same with bulk water exports or imports. Whether bulk water is a commodity is still disputed and efforts to trade it have met the reactions of the population. However, the postponement of accepting the commodification of bulk water simply makes the issue more complex. Finally, the notion of virtual water, even though not very popular, is going to play a crucial role in the future international market, bearing in mind water famine around the world. Since countries, private companies and individuals sell or buy water, in all of its form, across borders, the absence of international legislation guiding the transactions can be problematic. The overexploitation of freshwater resources and the disrespect for the protection of the aquatic environment can raise security questions, especially if the resources are shared by two or more states. The quest for profit should not disregard or override basic human needs, such as water consumption and sanitation. International law should bridge the gap between trade and water and assure that the words of Ismail Serageldin, the VicePresident of the World Bank that ―many of the wars this century were about oil, but those of the next century will be over water‖ fail to become reality.

REFERENCES

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Bottled water includes sparkling water, purified water, mineral water, spring water and artesian water. The three last types of water come from surface and underground founts. Klein, C. A. and Huang, L. Y. (2008). Cultural Norms as a Source of Law: The Example of Bottled Water, Cardozo Law Review, 30, 507-548. Slater, S. S. (2007). State Water Resource Administration in the Free Trade Agreement Era: As Strong As Ever, Wayne Law Review, 53, 649-714. Doria, M. F. (2006). Bottled Water versus Tap Water: Understanding Consumers‘ Preferences, Journal of Water and Health, 4, 271-276. See in general Glennon, R. (2007). Tales of French Fries and Bottled Water: the Environmental Consequences of Groundwater Pumping, Environmental Law, 37, 3-13. Gleick, P. H. and Cooley, H. S. (2009). Energy Implications of Bottled Water, Environmental Research Letter, 4, 1-6. Gashler, K. (2008). Thirst for Bottled Water Unleashes Flood of Environmental Concerns, The Ithaca (N.Y.) Journal, 1-3. In the Maine Wells‘ local citizens opposed the extraction of water from an aquifer of the region by a private company. Bodnar, S. (2009), [Maine] Wells Voters Reject Water Extraction; Community and Labor Action, Inside the Bottle, available at http://www.insidethebottle.org/maine-wells-voters-reject-water-extraction. Similar cases can be found in the USA, and especially in Michigan, Hauter, W. (2009). Michigan Citizens Win a Victory over Nestlé, Food and Water Watch, available at http://www.alternet.org/water/141184/michigan_citizens_win_a_victory_over_nestle, in Sacramento, Bacher, D. (2009). Groups Rally to Stop Nestlé‘s Raid on Sacramento

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Water, AlterNet., available at http://www.alternet.org/story/143397/groups_rally_ to_stop_nestl%C3%A9%27s_raid_on_sacramento_water/?comments=viewandcID=135 1111andpID=1351025, as well as in India, Havilland, C. (2003), Coca Cola Challenged in Kerala, available at http://news.bbc.co.uk/2/hi/south_asia/3125520.stm. Agreement on Technical Barriers to Trade, WTO Agreement, Annex 1 A, in World Trade Organization, op.cit., p. 121. For the specific Agreement see Appleton, A. E. (2007). The Agreement on Technical Barriers to Trade. In P. F. Macrory, A. E. Appleton and M. G. Plummer (Eds.), The World Trade Organization: Legal, economic and political analysis (1st edition, pp. 371-409), New York, ST: Springer. See for example, Committee on Technical Barriers to Trade, Notification by the United Kingdom, Spring Water and Bottled Drinking Water, G/TBT/N/GBR/14, 7 June 2006. Baumann, C. (2001). Water Wars: Canada‘s Upstream Battle to Ban Bulk Water Export, Minnesota Journal of Global Trade, 10, 109-132. Harmonized Commodity Description and Coding System Code § 22.01.09, available at www.upu.int/customs/en/country_list_en.pdf. This codex is an international codification system that was put forward by the World Custom Organisation and describes the commodities. Its purpose is the harmonisation of State tariffs. The codex is regulated by the International Convention on the Harmonized Commodity Description and Coding System, Can. TS 1988, No. 38, Brussels, 14 June 1983, as amended by the Additional Protocol of June 24 1986 which was implemented on January 1st 1988. For the said codex see Irish, M. (1993). Interpretation and Naming: The Harmonized System in Canadian Customs Tariff Law, 31, 89-150. General Agreement on Tariffs and Trade (GATT), 30 October 1947, 55 UNTS 194, that was extensively amended in 1994 as part of the Uruguay Round. The Uruguay Round produced a ―new 1994 GATT‖, which overrides the old one. Jackson, J. H. (2000). Jurisprudence of GATT and the WTO: Insights on Treaty Law and Economic Relations, Cambridge: Cambridge University Press. For the 1994 GATT, see Marrakesh Agreement Establishing the World Trade Organization, 15 April 1994, Annex 1A, in World Trade Organization, The Legal Texts: The Results of the Uruguay Round of Multilateral Trade Negotiations, Cambridge University Press, 1999, p. 17. ―(...) a "primary product" is understood to be any product of farm, forest or fishery, or any mineral, in its natural form or which has undergone such processing as is customarily required to prepare it for marketing in substantial volume in international trade‖. Id., Annex I, article XVI, Section B, paragraph 2. de Haan, E. J.(1997). Balancing Free Trade in Water and the Protection of Water Resources in GATT. In E. H. P. Brans, E. J. de Haan, A. Nolkaemper and J. Rinzema (Eds.), The Scarcity of Water: Emerging Legal and Policy Responses (1st edition, pp. 245-259). The Hague, ST: Kluwer Law International. North American Free Trade Agreement, Can.-Mex.-U.S., 8-17 December 1992, 32 ILM 289 (1993). Lowenfeld, A. F. (2003). International Economic Law. Oxford: Oxford University Press. NAFTA, supra 10, article 309 and GATT, id., article XI. Hall, N. D. (2010). Protecting Freshwater Resources in the Era of Global Water Markets: Lessons Learned from Bottled Water, University of Denver Water Law Review, 13, 3-65.

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[19] Despite the fact that the need to balance interstate trade and the protection of the environment is imperative, in practice, however, it is difficult to achieve. In support of this opinion is among others Rietvelt, Rietvelt, M. (2004-2005). Multilateral Failure: a Comprehensive Analysis of the Shrimp/Turtle Decision, Indiana International and Comparative Law Review, 15, 473-499. [20] These measures of course, cannot be applied in such a way that they consist of an arbitrary and unjustified discretion, nor can they set a masked restriction in international trade. NAFTA, supra 10, article 2101 and GATT, supra 12, article XX (g). This environmental restriction was designed for the export of products and goods and not for imports. Hence, this specific provision would be the most appropriate for restrictions in ―natural resources exports‖ like water. Matsuoka, K. (2001). Globalization and Water Resources Management: the Changing Value of Water, AWRA/IWLRI-University of Dundee International Specialty Conference. For the exceptions under article XX of the GATT see in general Van de Bossche, P. (2005), The Law and Policy of the World Trade Organization, Cambridge: Cambridge University Press and Chamovitz, S. (1991). Exploring the Environmental Exceptions in GATT article XX, Journal of World Trade, 25, 38-55. [21] Penman, H. L. (1970). The Water Cycle, Scientific American, 227, 98-110. For the importance of the water cycle in water resources management see Hofius, K. (2008). Evolving the Role of WMO in Hydrology and Water Resources Management, WMO Bulletin, 57, 147-151 and Liebscher, H. J. (20009). The Role of Hydrology in Water Resources Management. In H.-J. Liebscher, R. Clarke, J. Rodda, G. Schultz, A. Schumann, L. Ubertini and G. Young (Εds.), The Role of Hydrology in Water Resources Management: Proceedings of a symposium held on the island of Capri, Italy (1st edition, pp. 1-6), Wallingford: IAHS Publ. [22] The definition and characteristics of confined aquifers has caused much confusion, mainly to legal scholars. This can be seen clearly through the International Law Commission Draft Articles and Special Reporter Ch. Yamada, where there is an analysis of the differences between the ILC definitions and those of hydro-geologists concerning the term ‗confined aquifers‘. Ch. Yamada, Addendum to Second Report on Shared Natural Resources: Transboundary Groundwaters, U.N. Doc. A/CN.4/5 39/Add.1 (2004), paragraph 5. [23] ILC Resolution on Confined Transboundary Groundwater, 2 Yearbook of International Law Commission 1994, p. 135. For a short description of the specific ILC decision see Salman S. M. (1995). Groundwater: Legal and Policy Perspectives: Proceedings of a World Bank Seminar. Washington: World Bank Publications. [24] ILC Resolution on Confined Transboundary Groundwater, id., Preamble, paragraph 4. [25] World Trade Organization Appellate Body: Report of the Appelate Body in the United States – Standards for Reformulated and Conventional Gasoline, 20 May 1996, WT/DSZ/AB/R. For a commentary of the case see Waincymer, J. (1996-1997). Reformulated Gasoline under Reformulated WTO Dispute Settlement Proceedures: Pulling Pandora out of a Chapeau, Michigan Journal of International Law, 18, 141-182. [26] World Trade Organization Appellate Body: Report of the Appellate Body, United States-Import Prohibition of Certain Shrimp and Shrimp Products, 12 October 1998, WT/DSS58/AB/R. For an insight of the case see Warnker, J. (1999). The Shrimp-Sea Turtle Case before the World Trade Organization, Colorado Journal of International

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Environmental Law and Policy, 10, 27-39, Howse, R. (2002). The Appellate Body Rulings in the Shrimp/Turtle Case: a New Legal Baseline for the Trade and Environment Debate, Columbia Journal of Environmental Law, 27, 491-522, Jackson, J. H. (2000). Comments on Shrimp/Turtle and the Product/Process Distinction, European Journal of International Law, 11, 303-307, Bernazani, J. A. (2000). The Eagle, the Turtle, the Shrimp and the WTO: Implications for the Future of Environmental Trade Measures, Connecticut Journal of International Law, 15, 207233. Marrakesh Agreement Establishing the World Trade Organization, supra 12, Preamble. A reference to the definition of sustainable development states that environmental values and interests are taken into consideration by the WTO dispute settlement mechanisms. Treblicock, M. J. and Howse, R. (2005). The Regulation of International Trade. New York: Routledge. Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) notwithstanding Security Council Resolution 276 (1970), Advisory Opinion, 21 June 1971, ICJ Reports 1971, p. 16, paragraph 53. For this Advisory Opinion see Higgins, R. (1972). The Advisory Opinion on Namibia: Which UN Resolutions are Binding Under Article 25 of the Charter, International and Comparative Law Quarterly, 21, 270-286, Brown, P. (1971-1972). The ICJ 1971 Advisory Opinion on South West Africa (Namibia), Vanderbilt Journal of Transnational Law, 25, 213243, Lissitzyn, O. (1972). International Law and the Advisory Opinion on Namibia, Columbia Journal of Transnational Law, 11, 50-73 and Rovine, A. (1972). The World Court Opinion on Namibia, Columbia Journal of Transnational Law, 11, 203-239. Shrimp/Turtle case, supra 28, paragraph 128. For the interpretation followed by the Appellate Body see Puls, B. (1999). The Murky Waters of International Environmental Jurisprudence: A Critique of Recent WTO Holdings in the Shrimp/Turtle Controversy, Minnesota Journal of Global Trade, 8, 343-379. Bree, A. (1998-1999), Article XX GATT – Quo Vadis? The Environmental exception after the Shrimp/Turtle Appellate Body Report, Dickinson Journal of International Law, 17, 101-134. For future interpretive issues due to the Appellate Body‘s approach see Appleton E. (1999). Shrimp/Turtle: Untangling the Nets, Journal of International Economic Law, 2, 477-496. For example bulk water exports from Lesotho to South Africa are governed by a treaty. Treaty on the Lesotho Highlands Water Project (Lesotho, South Africa), 24 October 1986, available at http://www.fao.org/docrep/w7414b/w7414b0w.htm. For this specific treaty see Boadu, F. O. (1998), Relational Characteristics of Transboundary Water Treaties: Lesotho‘s Water Transfer Treaty with the Republic of South Africa, Natural Resources Journal, 38, 381-410. For instance, the Government of Bolivia allows the export of water to Chilean extractive companies. Turner, W. M. (2004). Bolivia Permits Bulk Export of Water to Chile, available at http://www.waterbank.com/Newsletters/nws39.html. In Alaska, for example, a company named Alaska Water Exports, scheduled the transport of bulk water to China, where it intends to build a water bottling factory and sale its water to a local private company. Anderson, D. B. (1998-1999). Selling Great Lakes Water to a Thirsty World: Legal Policy and Trade Considerations, Buffalo Environmental Law Journal, 6, 215-252.

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[34] The term bulk water export, describes the export of water with human intervention, including channels, tankers, trucks or pipelines. See Canadian Government: Strategy [to] Prohibit the Bulk Removal of Canadian Water, Including Water for Export, M2PRESSWIRE, 2 February 1999, WL 12604553 1999. For the pros and cons of bulk water trade see Tarlock, D. A. (2005). Water Transfers: A Means to Achieve Sustainable Water Use. In E. Brown Weiss, L. Boisson de Chazournes and N. Bernasconi-Ostewalder (Eds.), Fresh Water and International Economic Law (1st edition, pp.35-59), Oxford, ST: Oxford University Press. [35] This specific method might have several environmental impacts. One example is the Ganges River, Mirza. M. M. (2004). The Ganges Water Diversion: Environmental Effects and Implications- An Introduction. In M. M. Mirza (Ed.), The Ganges Water Diversion: Environmental Effects and Implications (pp.1-12). Dodrecht: Springer. [36] The case of great dams has been undermined in respect of the consequences they might have on climate change and even on violation of human rights. World Commission on Dams, Dams and Development: A New Framework for Decision-Making, The Report of the World Commission on Dams, Earthscan, 2000. For an analysis on the World Commission on Dams report see Salman, S. M. (2000-2001). Dams, International Rivers and Riparian States: An Analysis of the Recommendations of the World Commission on Dams, American University International Law Review, 16, 1477-1505. [37] Bayview Irrigation District and Ors v. United Mexican States, ICSID CASE No. ARB(AF)/05/01, Award of 19/06/2007. This case concerns a suit of 17 district irrigations, together with Texan farmers, in August 2004, who claimed they rights to the Rio Grande River, on the border of the two States. The applicants claim, moreover, that Mexico is violating the 1944 Water Treaty which grants the USA a right to 1/3 of the river‘s waters. According to the claimants, the measures adopted by Mexico for the management of the river‘s waters equal to an expropriation according to article 1110 NAFTA, to a discretionary treatment according to article 1102 NAFTA and are not in compliance with article 1105 NAFTA. For a detailed analysis of the dispute see Kibel, P. and Schutz, J. (2007). Rio Grande Designs: Texans‘ NAFTA Water Claim against Mexico, Berkley Journal of International Law, 25, 228-267 and Szydlowski, G. F. (2007). The commoditization of Water: A Look at Canadian Bulk Water Exports, the Texas Water Dispute, and the Ongoing Battle under NAFTA for Control of Water Resources, Colorado Journal of International Environmental Law and Policy, 18, 665686. [38] Bayview Award, id., paragraphs 104, 113 and 121. [39] Little, S. P. (1996). Canada‘s Capacity to Control the Flow: Water Export and the North American Free Trade Agreement, Pace International Law Review, 8, 127-159. [40] Sofer, A. (1999). Rivers of Fire: the Conflict of Water in the Middle East. Oxford: Rowman and Littlefield, Grover, V. I. (2006). Water: Global Common and Global Problems, Enfield: Science Publishers and Gruen, G. E. (2000). Turkish Waters: Source of Regional Conflict or Catalyst of Peace?. In S. Belkin and S. Gabbay (Εds.), Environmental Challenges (1st edition, pp. 565-579). Dodrecht: Kluwer Academic Publishers. [41] For water issues being tackled by countries of the region see Eckstein, Y. (2003). Groundwater Resources and International Law in the Middle East Peace Process, Water International, 28, 154-161.

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[42] Due to its vital importance water plays a significant role in defining the policies of Middle East countries. Starr, J. and Stoll, D. C. (1988). The Politics of Scarcity: Water in the Middle East, Boulder: Westview Press. [43] This plan was proposed by the then Turkish Prime Minister, Turgut Özal, in 1986. According to this 21 billion dollar plan, quantities of water from the Ceyhan and Seyhan rivers would be transported through two pipelines to other countries of the region. The west pipeline would transport water to Saudi Arabia through Syria and Jordan, while the east pipeline would have as a final destination the transport of water to Kuwait, Qatar, Bahrain and Oman. Ataman, M. (2002). Leadership Change: Özal Leadership and Restructuring in Turkish Foreign Policy, Alternatives: Turkish Journal of International Relations, 1, 120-153. [44] The Gulf States set as a prerequisite to the acceptance of the plan the overall settlement of the Arab-Israeli disputes, since they feared the Israeli interruption of the water flow in one of the pipelines. For an extensive analysis of the Gulf States qualms see Gruen, G. (2006). Turkish Water Exports: A Model for Regional Cooperation in the Development of Water Resources, available at http://www.ipcri.org/watconf/ papers/george.pdf. [45] Villa, C. J. (1993). California Dreaming: Water Transfers from the Pacific Northwest, Environmental Law, 23, 997-1026. [46] The McCurdy Group of Newfoundland Company asked to be granted a licence to extract 52 billion litres of water per year from the Gisborne Lake, in order to carry it to the Middle East by takers. Barlow, M. (2001). The Global Trade in Water from the booklet Blue Gold; the Global Water Crisis and the Commodification of the World‘s Water Supply, A Special Report Issued by the International Forum on Globalization (IFG), available at http://www.thirdworldtraveler.com/Water/Global_Trade_BG.html. Furthermore, in 1999, the NovGroup Ltd was granted a licence from the Ontario district to transport bulk water on tankers to Asia. However, the reaction of the residents, both in Canada as well as in the USA, was so strong that the licence was revoked. Cech, T. V. (2009). Principles of Water Resources, History, Development, Management and Policy, Hoboken: John Wiley and Sons. [47] Liel, A. (2001). Turkey in the Middle East: Oil, Islam and Politics, Boulder: Lynne Rienner Publishers. [48] Aspell, T. (2008). Drought-striken Cyprus Gets Water from Greece, available at http://worldblog.msnbc.msn.com/archive/2008/07/01/1177593.aspx. [49] Cossy supports that both criteria rendering water a commodity, in other words the degree of human intervention and price setting, are satisfied in the case of bulk water trade. Cossy, M. (2005). Le statut de l‘eau en droit international économique: principaux aspects au regard des règles de l‘Organisation mondiale du commerce. In L. Boisson de Chazournes and S. M. A. Salman (Eds.), Water Resources and International Law (1st edition, pp. 169-208). Leiden, ST: Martinus Nijhoff. [50] Tignino and Yared argue that water is not a financial commodity, because it is a public good, a human right and a common heritage of mankind. Tignino, M. and Yared, D. (2006). La Commercialisation et la Privtisation de l‘ Eau dans la Cadre de l‘ Organization Mondiale du Commerce, Revue Québécoise de Droit International, 19, 159-195.

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[51] The Preamble of the Agreement establishing the World Trade Organisation states: ―(…) while allowing for the optimal use of the world‘s resources in accordance with the objective of sustainable development (…) Agreement Establishing the World Trade Organization, supra 12, Preamble, paragraph 1. [52] The Preamble of the GATT urges States to exploit to the extreme their natural resources: ―(…) developing the full use of the resources of the world (...)‖ (emphasis added). GATT, supra 12, Preamble, paragraph 1. [53] Id., article 1, paragraph 1. For the specific clause see Van de Bossche, supra 20 and Hufbauer, G. C., Shelton Erb, J. and Starr, H. P. (1980). The GATT Codes and the Unconditional Most-Favored-Nation Principle, Law and Policy International Business, 12, 59-93. [54] Brown Weiss, E. (2005), Water Transfers and International trade Law. In E. Brown Weiss, L. Boisson de Chazournes and N. Bernasconi-Ostewalder (Eds.), Fresh Water and International Economic Law (1st edition, pp. 61-89). Oxford: Oxford University Press. [55] GATT, supra 12, article ΙΙΙ, paragraph 1. [56] GATT, id., article XΙ, paragraph 1. [57] Gleick, P. H. (2002). The World‘s Water 2002-2003: the Biennial Report on Freshwater Resources, Washington D.C.: Island Press. [58] GATT, supra 12, article XΙ, paragraph 2 (α). [59] According to Brown Weiss, temporary and consequently, justified under article XI, paragraph 2 (a), are considered the state restrictions that are imposed in cases of droughts, unexpected water supply contamination due to accidents or natural disasters, or other such extreme situations. Brown Weiss, supra 54. [60] The word ‗critical‘ sets a limit, that has to be met in case of a deficiency in order for the restriction to be justified based on the exception of article XI, paragraph 2 (a). The question that arises here is based on what criteria should the limit be defined. In a similar case, there has to be a levelling between the imposed restriction of the State and the food safety of the country. This indeed is the prerequisite of article 12, paragraph 1 of the Agreement on Agriculture. Agreement on Agriculture, 15 April 1994, Marrakesh Agreement Establishing the World Trade Organization, Annex 1A, 1867 U.N.T.S. 410, article 12, paragraph 1. [61] Apart from bulk water, if natural fresh water resources are considered also a product and their ecosystems necessary for the countries, then the exception of article XI, paragraph 2 (a) is activated in case of environmental risk. Brown Weiss, supra 54. Without expressing any disaccord to the previous opinion, granted, however, the lack of acceptance of bulk water transport as a product, it would be premature for the GATT regulations to extend to water in its natural form. [62] GATT, supra 12, article ΧΧ (b) and (g). The jurisprudence of the Dispute Settlement Body of the WTO has interpreted in a narrow manner certain provisions of this article. See Shrimp/Turtle case, supra 26 and General Agreement on Tariffs and Trade: Dispute Settlement Panel Report on United States Restrictions on Imports of Tuna, 30 ILM 1594 (1991). For the last case see also Kirgis Jr., F. L. (1992). Environment and Trade Measures After the Tuna/Dolphin Decision, Washington and Lee Law Review, 49, 1221-1226 and Black, D. J. (1992-1993). International trade v. Environmental

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Protection: The Cases of the US Embargo on Mexican Tuna, Law and Policy in International Business, 24, 123-156. Sporhase v. Nebraska, 458 US 941 (1982). For an examination of the case see Chan, A. H. (1983). Policy Impacts of Sporhase v. Nebraska, Journal of Economic Issues, 22, 1153-1167 and Williams S. F. (1983). Free Trade in Water Resources: Sporhase v. Nebraska ex rel. Douglas, Supreme Court Economic Review, 2, 89-110. United States Constitution, article I, section 8, clause 3. According to the Appellate Body, the chapeau of article ΧΧ is ―one expression of the principle of good faith‖. Shrimp/Turtle case, supra 26, paragraph 158. On the chapeau of article ΧΧ see Gaines, S. (2001). The WTO‘s Reading of the GATT Article XX Chapeau: A Disguised Restriction on Environmental Measures, University of Pennsylvania Journal of International Economic Law, 22, 739-863. Brown Weiss, supra 54, at p. 73. Virtual water is also known as ‗embedded‘ or ‗exogenous‘ water. The last is added to the so-called ‗indigenous‘ water of a country Haddadin, M. J. (2003). Exogenous Water: A Conduit to Globalization of Water Resources. In Α. Υ. Hoekstra (Ed.), Virtual Water Trade, Proceedings of the International Expert Meeting on Virtual Water Trade (pp. 159-169). Delft: Value of Water Research Report Series No. 12. The meaning of virtual water emerged in the `90s and is gaining more and more the attention of people concerned with water management and especially, the management of water relevant to food production. Renault, D. (2002). Value of Virtual Water in Food: Principles and Virtues, Paper presented at the UNESCO-IHE Workshop on Virtual Water Trade, Delft, available at ftp://ftp.fao.org/agl/AGLW/ESPIM/CDROM/documents/5M_e.pdf. Allan, J. A. (2003). Virtual Water – The Water, Food and Trade Nexus; Useful Concept or Misleading Metaphor?, Water International, 28, 4-11. See in general Wichelns, D. (2004). The Policy Relevance of Virtual Water Can Be Enhanced by Considering Comparative Advantage, Agricultural Water Management, 66, 49-63. Countries tackling water shortage can import products that need a lot of water for their production, instead of producing them domestically. This way, they save water, maintain their natural resources and distribute water for other causes. Chapagain, A. K. and Hoekstra, A. Y. (2008). The Global Component of Freshwater Demand and Supply: An Assessment of Virtual Water Flows Between Nations as a Result of Trade in Agricultural and Industrial Products, Water International, 33, 19-32. For instance, the import of virtual water covers the 80-90% of water needs in Jordan. World Water Council, Water Trade and Geopolitics, 3rd World Water Forum, 16-23 March 2003, Kyoto. Contra see Kirby, who holds that virtual water could be a solution, ―but the amounts involved would be immense, and the energy needed to transport them, gargantuan. And affordable, useable energy will probably soon be a bigger problem than water itself.‖, Kirby, A. (2004). Water Scarcity: A Looming Crisis?, available at http://news.bbc.co.uk/2/hi/science/nature/3747724.stm. Doubts on the encouragement of virtual water trade are expressed by Kumar, D. and Kumar, S. M. and Singh, O. P.

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Vasiliki-Maria Tzatzaki (2005). Virtual Water in Global Food and Water Policy Making: Is There a Need for Rethinking?, Water Resources Management, 19, 759-789. Lamy, P. (2007). Friend, not Foe, Connected Dreams, Globalization and the Environment, Our Planet, the magazine of the United Nations Environment Programme. In favour of virtual water trade see Allan, Allan, J. A. (1998). Virtual Water: A Strategic Resource. Global Solutions to Regional Deficits, Groundwater, 36, 545-546. This offers the possibility to find the environmental impacts of the consumption of a specific product, knowing that, the virtual water content entails the knowledge of the amount of water necessary for the production of this specific product. The concept of ‗water footprint‘ is closely related, since it constitutes the accumulative context of the virtual water contained in all goods and services consumed by every person separately in a country. Hoekstra, A. Y. and Hung, P. Q. (2003). Virtual Water Trade: A Quantification of Virtual Water Flows Between Nations in Relation to International Crop Trade, In Α. Υ. Hoekstra (Ed.), Virtual Water Trade, Proceedings of the International Expert Meeting on Virtual Water Trade (pp. 25-47). Delft: Value of Water Research Report Series No. 12. Allan, J. A. (2003). Virtual Water Eliminates Water Wars? A Case Study from the Middle East. In Α. Υ. Hoekstra (Ed.), Virtual Water Trade, Proceedings of the International Expert Meeting on Virtual Water Trade (pp. 137-145). Delft: Value of Water Research Report Series No. 12. Dublin Statement on Water and Sustainable Development, International Conference on Water and the Environment, Dublin, 31 January 1992, available at http://www.gwpforum.org/servlet/PSP?iNodeID=1345, Principle no. 4. Water as a financial, as well as a social commodity, is recognised in Chapter 18.8 of Agenda 21, that was adopted the in the same year at the Rio Conference on Environment and Development. United Nations, Rio Declaration on Environment and Development, Report of the United Nations Conference on Environment and Development, A/CONF.151/26 (Vol. I), 12/08/1992, Agenda 21. Agreement on Agriculture, supra 60. Id., Preamble, paragraph 6. Mori, K. (2003). Virtual Water Trade in Global Governance. In Α. Υ. Hoekstra (Ed.), Virtual Water Trade, Proceedings of the International Expert Meeting on Virtual Water Trade (pp. 119-124). Delft: Value of Water Research Report Series No. 12.

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Chapter 12

OPTIMIZATION OF CONDENSER WATER LOOP IN HVAC SYSTEMS: GENETIC ALGORITHM APPROACH 1

R. Uche1 and E. O. Diemuodeke2 Department of Mechanical Engineering, Federal University of Technology, P.M.B 1526 Owerri, Nigeria 2 Department of Mechanical Engineering, University of Port Harcourt, Port Harcourt, Rivers State

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ABSTRACT Energy optimization of a condenser water loop operation in heating, ventilation and air conditioning (HVAC) system has been done. The objective function, which minimizes the operating costs, was formulated on the analysis of thermal interaction between the cooling tower and chillers. The Genetic Algorithm (GA) was used to optimize the changes of outdoor environment and indoor cooling load based on the objective function formulated. The approach has the capability of solving the combinatorial optimization problem with both discrete variables and continuous variable.

Keywords: Condenser, Water Loop, Genetic Algorithm (GA), Energy, Optimization, Thermal, Discrete Variables.

1. INTRODUCTION A typical centralized HVAC system comprises of condenser water loop, together with chillers, indoor air loops and chilled water loop to provide comfort environment for the conditioned space (Stoecker, 1975). The process of a condenser water loop consists of condenser, condenser water piping and pumps, and cooling towers. Condensers transfer indoor cooling load and heat generated by compressors into condenser water pipe where 

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condenser water pumps provide the energy to overcome the friction loss and deliver condenser water to cooling towers. Cooling towers reject heat to the environment through heat and mass transfer to the ambient air. The control and optimization has been considered as one of the most difficult problems for practice control engineers (Ahn and Mitchell, 2001). Condenser water loop is one of the five main function loops and its operation has significant effect to the overall system performance. The main issues for efficient operation of condenser water loop are the performance of cooling towers as well as the interactions between cooling towers (Soylemez, 2001), condenser water pumps and chillers. For cooling towers, Cassidy and Stack‘s work (1988) showed that varying the speed of cooling tower fans is a good way to reduce energy consumption. Braun and Doderich (1990) proposed Near-optimal control of cooling towers based on parameter estimated from design data. This method was further adopted by Cascia (1999) to simplify the component model and provide equations for determining the set points of near-optimal control. For interactions between chillers and cooling towers, Shelton and Joyce (2001) showed in their work that 1.5gpm/Ton condenser water flow rate as an optimal solution. Later, Kirsner (1996) pointed out that high condenser water flow rate, 3 gpm/Ton, has good performance at full load condition, while low condenser water flow rate, 1.5gpm/Ton, has advantages at part load conditions. Michael and Emery (1994) analyzed the cost-optimal selection of the cooling tower range and approach and provided the design information for hermetic centrifugal and reciprocating chillers. Schwedler (1998) studied the variation of condenser water supply temperature and used several examples to demonstrate his main idea that the lowest possible leaving tower water temperature does not always conserve system energy. However, his research only considered the fans with half-speed and full-speed conditions, which was not conclusive. Lu and Cai (2006) work showed that the optimum operation of the water loop condenser has a strong relation with the operating range of the cooling tower; the wet-bulb temperature, Twb; and condenser water supply temperature, Tcws; and the interaction between chillers and cooling towers. It was established that the optimal operating range of a cooling towers lied in the portion where heat rejection rate of the cooling tower increases with either the increased airflow rate or increased water flow rate, and vice versa. Also, if the airflow rate is kept at 13 kg/s at 25oC wet-bulb temperature instead of 9 kg/s, the power consumption of fan and pump is 6.11kW. Compared with power consumption of 5.26 kW at 9 kg/s at optimal point, almost 17% energy can be saved when the ambient wet-bulb temperature is changed from 25 oC to 30 oC. This implies that the optimal operating points are different for the same heat rejection rate under different wet-bulb temperature. In spite of the progress made in recent years on individual component modeling, control, optimization and operation rules, there is still lack of systematic approach which consider the condenser water loop as a system, to optimize its operation. Therefore, this paper presents a novel real time optimization strategy for condenser water loop. By considering characteristics of cooling towers, effects of different ambient environment, interactions between chillers and cooling towers, the energy efficiency of the condenser water loop can be formulated as a standard optimization problem. The total energy cost can be minimized by optimizing set points of manipulated variables, such as the flow rate of condenser water, airflow rate in cooling towers and condenser water supply temperature. The GA consists of binary-coded string population and four basic operators: selection, crossover, mutation and mating are used

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to search the optimal solutions. This method is suitable to deal with both single chiller and multi-chiller central parts and has potential to substantially reduce the operating cost.

2. ANALYSIS OF CONDENSER WATER LOOPS

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The condenser water temperature entering the chiller affects the chiller capacity and hence the chiller power consumption (Salsbury and Diamond, 2000). The higher TCWS leads to lower chiller efficiency, whereas, lower TCWS results in higher chiller efficiency. Therefore, reducing condenser water supply temperature can reduce chiller energy consumption. However, this will be penalized by increased power usage in cooling tower side in order to achieve the lower TCWS condition. Figure 1 illustrates the effect of condenser water supply temperature to chiller COP using manufacture‘s data (Stoecker, 1995). As the airflow and condenser water low increase, the fan power and condenser water pump power increase cubically. It has also been generally acknowledged (Castrol et al, 2000), TCWS decreases resulting in higher COP and lower energy consumption of chillers. On the other hand, however, condenser water return temperature in turn affects the heat exchange efficiencies in cooling towers. When condenser water supply temperature decreases, condenser water return temperature also decreases for the cooling load. This results in the lower efficiencies of the cooling tower under the same ambient wet-bulb temperature as the enthalpy difference between ambient air and condenser water becomes smaller. The optimal operating point occurs at a point where the rate power increment in fans and pumps is equal to the rate of power reduction in chillers.

Figure 1. Effect of TCWS to Chiller COP.

To illustrate the relationship between total power consumption and condenser water supply temperature, let‘s look at the total power consumption of condenser water loop with ambient wet-bulb temperature and cooling load are at 25oC and 400 TR, respectively. The total energy consumption for different condenser water supply temperature is given in Figure 2.

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total energy consumption, Ptotal [kW]

280 278 276 274 272 270 268 266 264 262 27

28

29

30

31

32

33

34

35

condenser water supply temperature, Twcs [oC]

Figure 2. Relationship between TCWS and Ptotal.

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3. GENETIC ALGORITHM OPTIMIZATION METHOD The concept of GA was developed by Holland and his colleagues in the 1960s and 1970s (Holland, 1975). GA is inspired by the evolutionist theory explaining the origin of species. In nature, weak and unfit species within their environment are faced with extinction by natural selection. The strong ones have greater opportunity to pass their genes to future generations via reproduction. In the long run, species carrying the correct combination in their genes become dominant in their population. Sometimes, during the slow process of evolution, random changes may occur in genes. If these changes provide additional advantages in the challenge for survival, new species evolve from the old ones. Unsuccessful changes are eliminated by natural selection. In GA terminology, a solution vector x є X is called an individual or a chromosome. Chromosomes are made of discrete units called genes. Each gene controls one or more features of the chromosome. In the original implementation of GA by Holland, genes are assumed to be binary digits. In later implementations, more varied gene types have been introduced. Normally, a chromosome corresponds to a unique solution x in the solution space. This requires a mapping mechanism between the solution space and the chromosomes. This mapping is called an encoding. In fact, GA works on the encoding of a problem, not on the problem itself. GA operates with a collection of chromosomes, called a population. The population is normally randomly initialized. As the search evolves, the population includes fitter and fitter solutions, and eventually it converges, meaning that it is dominated by a single solution. Holland also presented a proof of convergence (the schema theorem) to the global optimum where chromosomes are binary vectors. GA uses three operators to generate new solutions from existing ones: selection, crossover and mutation. The crossover operator is the most important operator of GA. In crossover, generally two chromosomes, called parents, are combined together to form new chromosomes, called offspring.

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The parents are selected among existing chromosomes in the population with preference towards fitness so that offspring is expected to inherit good genes which make the parents fitter. By iteratively applying the crossover operator, genes of good chromosomes are expected to appear more frequently in the population, eventually leading to convergence to an overall good solution. The mutation operator introduces random changes into characteristics of chromosomes. Mutation is generally applied at the gene level. In typical GA implementations, the mutation rate (probability of changing the properties of a gene) is very small and depends on the length of the chromosome. Therefore, the new chromosome produced by mutation will not be very different from the original one. Mutation plays a critical role in GA. As discussed earlier, crossover leads the population to converge by making the chromosomes in the population alike. Mutation reintroduces genetic diversity back into the population and assists the search escape from local optima. Reproduction involves selection of chromosomes for the next generation. In the most general case, the fitness of an individual determines the probability of its survival for the next generation. There are different selection procedures in GA depending on how the fitness values are used. Proportional selection (roulette wheel), ranking, and tournament selection are the most popular selection procedures. The procedure of a generic GA (Goldberg, 1989) is given in the palette as follows: start Step 1: Set t=1. Randomly generate N solutions to form the first population, P1. Evaluate the fitness of the solution in P1; Step 2: Crossover: Generate an offspring population Qt as follows: 2.1. Choose two solutions x and y from Pt based on the fitness values; 2.2. Using a crossover operator, generate offspring and add them to Qt; Step 3: Mutation: Mutate each solution x є Qt with a predefined mutation rate; Step 4: Fitness assignment: Evaluate and assign a fitness value to each solution x є Qt based on its objective function value and infeasibility; Step 5: Selection: Select N solutions from Qt based on their fitness and copy them to Pt+1; Step 6: If the stopping criterion is satisfied, then terminate the search and return to the current population; else Set t=t+1 go to Step 2; end_if stop

4. PROBLEM FORMULATION Figure 3 shows the condenser water loop system block diagram. Without loss of generality, it is assumed that the chilled water supply temperature, TCHWS, and chilled water flow rate inside chiller, mCHW, are kept constant, whereas the chilled water return temperature, TCHWR, varies with the cooling load in the conditioned space. The manipulated variables of the system for control and optimization are as follows:

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Figure 3. The Block Diagram of Condenser Water Loop.

 

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 

The numbers of operating chillers i, condenser water pumps j, and cooling tower fans k. The condenser water flow rate mw,j, controlled by the jth Variable-Speed Drive (VSD) condenser water pump. The airflow rate in cooling towers ma,k, controlled by the kth VSD cooling tower fan. The condenser water supply temperature, TCWS, controlled by the combination of the total condenser water flow rate, mW, and airflow rate, ma, in cooling towers.

4.1. Objective Function The objective is to minimize total power consumption, Ptotal, of the condenser water loop system, and is given as

min Ptotal  Pchiller  Ppump  Pfan

(1)

The power consumption of the pumps and fans, Ppump and Pfan, respectively with VSD proposed by Kreider and Rabl (1994) is given as

Ppump

  mW , j   Ppn , j  do  d1  m  j  Wn, j 

  mW , j   d 2    mWn, j

2

  mW , j   d3    mWn, j

  

3

   

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(2)

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Pfan

 m   Pfn ,k  eo  e1  a ,k m  k  an,k 

  ma ,k   e2    man ,k

2

  ma ,k   e3    man ,k

  

3

   

243

(3)

The expression for the chiller power consumption, Pchiller, by Stoecker (1995) is given as

Pchiller   Qcap ,i .COPnom ,i  PLRadj ,i  . Tempadj ,i 

(4a)

i

PLRadj ,i

 Q  bo  b1  i Q  cap ,i

  Q   b2  i   Qcap ,i

  

2

Tempadj ,i  co  c1TCHWS  c2TCHWS 2  c3TCWS  c4TCWS 2  c5TCHWSTCWS

(4b)

(4c)

where Ppn,j is the jth nominal pump power at full-load; Pfn,k is the kth nominal fan power at fullload; d0…d3 the coefficients of pumps for part-load conditions; e0…e3 the coefficients of fans for part-load; b0…b2 the constant coefficients to determine PLRadj,i; c0…c5 the constant coefficients to determine Tempadj,i; mWn,j is the nominal jth pump water flow rate at full-load; man,k is the nominal kth fan airflow rate at full-load; Qcap,i is the nominal capacity of the ith chiller; COPnom,i is the nominal coefficient of performance of the ith chiller and Qi is the real cooling load provided by the ith chiller.

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4.2. Constraints The objective function of Equation 1 is subject to the following constraints:

mW , j ,min  mW , j  mW , j ,max ;

(1‘)

ma,k ,min  ma,k  ma,k ,max ;

(2‘)

TCWS ,min  TCWS  TCWS ,max ;

(3‘)

Q  mCHW c pw (TCHWR  TCHWS ) ;

(4‘)

Q  Pchiller  mW c pw (TCWR  TCWS ) ;

(5‘)

mW   mW , j ;

(6‘)

Q  Pchiller  Qrej

(7‘)

j

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Constraints (1‘) through (3‘) limit all variables in their operating range. The cooling load is calculated by constraint (4‘) and used in constraints (5‘) and (7‘). Constraint (5‘) demands the condenser transfer the corresponding heat to cooling towers. Constraint (7‘) implies that the heat is completely rejected to the environment by the cooling towers. We adopt for engineering application, equations for calculating the heat rejection of the cooling towers, Qrej, by Lu and Cai (2001):

Qrej   Qrej ,k

(5)

k

Qrej ,k   a,k ma,k (hs ,w,i  ha,i )

 a ,k

m  a0  a1  a ,k m  W ,k

  ma ,k   a2 TCWR  Twb   a3    mW ,k m  2  a4 TCWR  Twb   a5  a ,k  TCWR  Twb  m   W ,k 

(6a)

  

2

hs ,W ,i  f TCWR 

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and ha ,i  f Tdb  Twb 

(6b)

(6c) (6d)

where Qrej,i is the heat rejection rate of the kth cooling tower; εa,k is the heat transfer effectiveness; a0…a5 the constant coefficients to determine εa,k; hs,W,i is saturation air enthalpy at TCWR; ha,i is the inlet air enthalpy of cooling tower and Tdb is the ambient dry-bulb temperature. The single-chiller systems can be considered as a special case of multi-chiller installations, in which there is only one chiller, one condenser water pump and one cooling tower fan. The combination of multiple chillers, pumps and fans is no longer required in the problem solving process.

4.3. Fitness Function Construction The fitness function is expressed in the following equation.

fitness  Ptotal  Pf 1  Pf 2  Pf 3

7a

Pf 1  Q  mCHW c pw (TCHWR  TCHWS )

7b

with

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Pf 2  Q  Pchiller  mW c pw (TCWR  TCWS )

7c

Pf 1  Q  Pchiller  Qrej

7d

5. RESULT AND DISCUSSION To illustrate the advantages of the GA optimization methods for searching the optimal operating points over the common optimal operating point control method and the modified GA (MGA) method (Lu and Cai, 2006), an application example data are given below (Lu and Cai, 2006):       

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

A centralized air conditioning system has four chillers, four condenser water pumps, and four cooling towers. Four chillers have the same nominal cooling load capacity, 500 TR. The chiller water supply temperature is 7.2 oC. The nominal condenser water supply temperature is 29.4. The energy consumption of each chiller is 0.6 kW/TR at full load condition. Each chiller has one condenser water pump and its nominal water flow rate is 100 kg/s. Each cooling tower is equipped with a fan of 30 kW at full load and can provide 30 kg/s airflow rate. All pumps and fans are equipped with VSDs and their speed ranging from 50% to 150% of full load.

To compare with the optimal operating point control method, a commonly used increment/decrement chiller staging method with fixed condenser water flow rate and airflow rate control strategy is used with following operating conditions. The condenser water flow rate is fixed at 100 kg/s per condenser water pump and the pump is staging on with the corresponding chiller.  The airflow rate in cooling tower is fixed at 30 kg/s when the cooling fans operating under the rated speed. The cooling load and ambient wet-bulb temperature profiles are given in Table 1. 

The total power consumption of the condenser water loop HVAC system with optimal operating control from this work, MGA and the commonly used method are plotted in Figure 4. It can be seen from Figure 4, the average energy consumption by using the GA optimization method is nearly 13% less than that of commonly used control strategy. Also, there is an average improvement of 3.1% over the MGA proposed by Lu and Cai (2006). The reason may be due to the selection operator, the probability of mutation and the search space used in the MGA method.

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Time [hours]

Cooling Load [TR]

Ambient Wet-bulb Temperature [oC]

1

800

20.5

2

900

20

3

700

20

4

600

19.9

5

705

19.8

6

605

19.7

7

905

20.5

8

995

22.5

9

1440

26

10

1700

26.1

11

1450

26.1

12

1100

27

13

850

27

14

1460

27

15

1600

27

16

1950

27

17

1850

27

18

1602

24.5

19

1605

25

20

1005

20.5

21

1100

20

22

990

20

23

780

20

24

782

20

In practice, the energy savings resulted from operating points optimization may be different from system to system. In general, however, it can be expected that the proposed GA optimization method can substantially reduce the energy consumption of the condenser water loops. total power consumption (kW)

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Table 1. Measured Cooling Load and Ambient Wet-bulb Temperature

1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0

Common MGA GA

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

time (hour)

Figure 4. Power Consumption of the three Methods/ Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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CONCLUSION This paper proposed GA optimization method of energy saving for condenser water loop. To clearly identify optimization opportunities, detailed characteristic analysis of the system components showed the interactions of control variables inside the cooling tower and between the cooling towers and the chillers. Based on the analysis, a model-based optimization method was proposed and GA was employed to find the optimal solutions. The proposed GA was implemented in Visual Basic for Application in MS Excel (Excel VBA) computer programme, which has the capability of plotting results. As other loops in HVAC systems have similar characteristics, the methodology developed could easily be extended to them.

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REFERENCES Ahn, B.C. and Mitchell, J.W. (2001) Optimal Control Development for Chilled Water Plants Using A Quadratic Representation, Energy and Buildings, Vol. 33, 2001, pp.371-378. Braun, J.E. and Doderrich, G.T. (1990) Near-Optimal Control of Cooling Towers for ChilledWater Systems, ASHRAE Trans., Vol. 96, No. 2, pp 806-813. Cascia, M.A. (1999) Digital Controller for A Cooling and Heating Plant Having NearOptimal Global Set Point Control Strategy, US Patents 5963458. Cassidy, M.P. and Stack, J.F. (1988) Applying Adjustable Speed AC Drives to Cooling Tower Fans, Annual Petroleum and Chemical Industry Conference, IEEE. Castro, M.M., Song, T.W. and Pinto, J.M. (2000) Minimization of Operation Costs in Cooling Water Systems, Chemical Engineering Research and Design, Trans. of Institute of Chemical Engineers, Vol.78, No.2, pp. 192-201. Goldberg, D.E. (1989) Genetic Algorithm Search, Optimization and Machine Learning, Reading, M.A: Addison-Wesley. Holland, J.H. (1975) Adaptation in Natural and Artificial Systems, Ann Arbor: University of Michigan Press, Michigan. Kirsner, W. (1996) 3 GPM/TR Condenser Water Flow Rate: Does It Waste Energy?, ASHRAE Journal, Vol. 38, No. 2, pp. 63-69. Kreider, J.F. and Rabl, A. (1994) Heating and cooling of Buildings-Design efficiency, McGraw-Hill Inc. New York. Lu, L. and Cai, W. (2001) A Universal Engineering Model for Cooling Towers, ASHRAE Winter Meeting. Lu, L. and Cai, W. (2006) Application of Genetic Algorithms for Optimization of Condenser Water Loop in HVAC Systems, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang. Michael, K.M. and Emery, A.F. (1994) Cost-Optimal Analysis of Cooling Towers, ASHRAE Trans., Vol. 100, No.2, pp. 92-101. Salsbury, T. and Diamond, R. (2000) Performance Validation and Energy Analysis of HVAC Systems Using Simulation, Energy and Buildings, Vol. 32, pp. 5-17. Schwedler, M. (1998) Take it to the Limit…or just Halfway, ASHRAE Journal, Vol. 40 No. 7, pp-32-39. Shelton, S.V. and Joyce, C.T. (1991) Cooling Tower Optimization for Centrifugal Chillers, ASHRAE Journal, Vol. 33, No. 6, pp 28-36.

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Soylemez, M.S. (2001) On the Optimal Sizing of Cooling Towers, Energy Conversion and Management, Vol. 42, No. 7, pp. 783-789. Stoecker, W.F. (1975) Procedures for Simulating the Performance of Components and Systems for Energy Calculations, ASHRAE, New York. Stoecker, W.F. (1995) Industrial refrigeration Handbook, McGraw-Hill Inc. New York.

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Chapter 13

FINANCIAL ANALYSIS OF IMPLEMENTATION OF RAINWATER UTILIZATION SYSTEM IN MODERNIZED MULTI-FAMILY RESIDENTIAL BUILDING Daniel Słyś Rzeszow University of Technology, Department of Infrastructure and Sustainable Development, al. Powstańców Warszawy 6, 35-082 Rzeszow, Poland

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ABSTRACT In this chapter, results of a financial analysis are presented for an investment consisting in modernization of multi-family residential building water supply facilities through introduction of a rainwater collection, storage and utilization system. The related calculations were carried out with the use of a simulation system representing rainwater utilization in residential buildings that was additionally extended with functions performing calculations of economic ratios. The calculations were based on archival data concerning precipitation levels. In the analysis, both currently applicable municipal water prices and those obtained as a result of forecasting were taken into account.

Keywords: rainwater utilization system, simulation, financial analysis

1. INTRODUCTION The issue of limited water resources afflicts not only certain areas of Africa, Asia or Australia, but also some European countries. Poland‘s water resources are classified among the lowest in Europe, although the country is situated in the central part of the continent within the temperate climatic zone. Annual per capita water volume available in Poland 

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Daniel Słyś

amounts to about 1,600 m3, a figure almost three times less than Europe‘s average. The seriousness of the water deficit in Poland can be illustrated by comparing its water resources to those available in African countries usually regarded as examples of territories poor in water. Comparison of global statistical data concerning per capita water resources shows that Poland‘s figure is only slightly higher than that of Egypt, a country situated in the tropics and within a very dry climate zone, and even lower than those observed in such countries as Syria, Ethiopia, India and Iran. Despite such unfavorable hydrological balance existing in Poland, rainwater utilization systems (RWUS) are relatively seldom used as sources of water for possible use in public utilities, industry and agriculture. In many countries, rainwater is utilized both in residential (Ghisi et al., 2006, 2007; Słyś, 2009) and commercial (Chilton et al., 1999) buildings as well as in sports facilities (Zaizen et al., 1999). Studies performed to date (e.g., Dixon et al., 1999; Fewkes, 1999; Vaes and Berlamont, 2001; Villarreal and Dixon, 2007) were aimed mainly at determination of rainwater quantity potential in different parts of the world, possible economies resulting from replacement of municipal water with rainwater, and research on water quality and its usefulness for, among other things, human consumption (Sazakli et al., 2007). In most cases the research results were optimistic as for possibilities to use rainwater from both a quantity and quality point of view. A separate issue that is of special importance from the investor‘s perspective consists in solution of the decision problem concerning implementation or abstaining from implementation of a rainwater utilization system. In that case it is very important to carry out a detailed economic analysis of the related investment.

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2. PROBLEM FORMULATION From the financial point of view, an investment project consists in a long-term engagement of economic resources aimed at achievement of benefits exceeding the initial investment outlays. It is the same in the case of residential building water supply system modernization through construction of a system of rainwater collection, storage and utilization. Application of a RWUS should bring some real benefits for the investor consisting in reduction of costs related to supplying the building‘s residents with water. This chapter presents results of financial analysis preformed for a modernized multifamily building in which implementation of RWUS is provided. Analysis of the investment‘s economical effectiveness was performed according to applicable standards set out in recommendations issued by the United Nations Industrial Development Organization (UNIDO). The analysis accounted for investment outlays as well as the system operation and maintenance costs. Calculations were performed for several variants corresponding to different rainwater tank capacities. Assessment of the investment‘s economic effectiveness was carried out both for municipal water prices applicable currently and for those forecasted for the future.

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3. SIMULATION MODEL

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The RWUS simulation model was constructed in accordance with rules concerning decision-making-oriented mathematical modeling (Makowski, 2005). The simulation program based on meteorological data concerning precipitation performs calculations of daily rainwater consumption volumes. The calculations are of recursive nature and are performed according to the algorithm presented in Figure 1. In a next step, the annual average volume of rainwater used in the building VRav is calculated. Results of these calculations form the basis for further calculation carried out by the program aimed at determination of economical indices for each of the analyzed investment variants and for the adopted investment life cycle.

Figure 1. General algorithm of recursive calculations used in the simulation model. Vw – water volume in storage tank, Vr – volume of rainwater inflow to storage tank, Vd – water demand for specific purpose, Vu – volume of rainwater outflow from storage tank to equipment using it, Vt – capacity of the storage tank.

3.1. Assumptions In the course of development of the RWUS simulation model, the following assumptions were adopted:     

the storage tank capacity is fixed, Vt = constant; the largest volume of rainwater accumulated in storage tank, Vr, equals the capacity of the storage tank, Vt; demand for water in the house is satisfied primarily by water accumulated in the storage tank, and only then by water from the water-supply system; any excess of rainwater, i.e. quantities exceeding the capacity of storage tank, Vt, is drained to sewage systems or to other rainwater-using equipment; demand for water depends on the number of inhabitants, average water requirements for specific purpose, as well as the time of the year, Vs = constant;

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the simulation model does not take into account the effect of wind direction and strength, as well as that of air temperature and humidity; the scale of rainwater flow depends on the type of roofing, the roof surface area, roof inclination and the type of precipitation (rain, snow, etc.); the capacity of the storage tank is higher than the daily demand for water by the respective sanitary system, Vt > Vd; the model does not take into account the phenomenon of snow sublimation; because of the small size of the systems, a time shift between the precipitation itself and the rainwater inflow to storage tank was not considered; the precipitation has a random character, and its quantity is the parameter that characterizes it in the developed simulation model; LCA analysis period of T = 30 years was adopted (service life of rainwater tank and water distribution piping); based on 10-year archival data, the annual average volume of rainwater used in the sanitary system was calculated as well as the annual average of municipal water that must be purchased.

3.2. Decision Variables The decision variables in the model are denoted as xk – meaning implementation of a RWUS with storage tank with Vtk volume (k  K, K = { 1, 2, ..., m}, m  N). Therefore, m investment variants are analyzed (m of them differing with tank volume Vtk).

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3.3. Input Parameters The input parameters of the simulation model are as specified below:            

precipitation level over a time interval, p, mm; average demand for water for specific purpose in time interval per inhabitant, Vd, m3/day (24hrs); number of inhabitants in the building, M, number of inhabitants; roof surface, F, m2; average coefficient of rainwater flow from the roof surface area, ; storage tank capacity, Vtk, m3; purchase price for 1 m3 of municipal water, Cw, EUR; purchase price for 1 kWh of electric power (according to tariff for households), ce, EUR; discount rate r for analyses in fixed and variable prices, –; capital investment for each of k RWUS variants, INVk, EUR; annual maintenance costs for each of k RWUS variants, Cck, EUR/year; investment life cycle, T, years.

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3.4. Output Variable The output parameters of the simulation model are quantities representing effectiveness of the investment:   

Simple Pay Back SPB, year; Net Present Value NPV, EUR; Internal Rate of Return IRR; %.

The Simple Pay Back (SPB) determines a period in which financial income from an investment equalize the initial capital investment for each of the analyzed investment variants. SPBk parameter values for a rainwater utilization system can be determined by means of formula (1).

SPB  INVk / VRavk  cw 

(1)

where: INVk – capital investment for each of k RWUS variants, INVk, EUR; cw – purchase price for 1 m3 municipal water, EUR; VRavk – annual average of rainwater volume used in RWUS for k-th investment variant, 3 m /year: Tt

VRavk   VRyk / Tt

(2)

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y 1

where: Tt – period of the used meteorological data on precipitation, years; VRyk – annual volume of rainwater used in RWUS for k-th investment variant, m3/year: 365

VRyk   Vu jk

(3)

j 1

where: Vujk – daily volume of rainwater outflow from storage tank to the equipment for k-th investment variant, m3 The Net Present Value (NPV) is the difference between discounted revenues and expenses incurred for the undertaking within an adopted time-scale. Cash flows are discounted as on the investment starting moment. The NPVk value, under assumption of the discount rate being fixed throughout the whole analyzed period, is determined by formula (4). n

NPVk   t 0

FCFtk (1  r )t

(4)

where: FCFtk – free cash flows related to the investment in question in consecutive periods of time for k-th investment variants, EUR; Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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Daniel Słyś r – discount rate r for analyses in fixed and variable prices, –; n – analysis period, year. FCFtk value in the simulation model is determined by means of formula (5). n 1

FCFt k   cw VRavk   cp VRavk  Cck  INVk 

(5)

t 1

where: Cck – maintenance costs for k-th variant of the system, EUR; cp – cost related to transport of 1 m3 rainwater from the tank to users, EUR/m3:

cp 

VRavk  g  h  ce  3.6 106

(6)

where: ce – purchase price for 1 kWh of electric power according to tariff applicable to households, EUR/kWh; g – acceleration of gravity, m/s2; Δh – average elevation of sanitary facilities with respect to minimum rainwater level in the tank, m;  – efficiency of the motor-pump system, –; ρ – water density, kg/m3.

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The Internal Rate of Return (IRR) means such discount rate at which the Net Present Value (NPV) calculated for the whole system operation period equals zero. The parameter for the investment analyzed herein is determined by formula (6). n

IRRk  r   t 0

FCFtk 0 (1  r )t

(6)

3.5. Data Used for the Model The simulation studies concerning operation of rainwater utilization system were carried out for a multi-family building with the following parameters:    

number of floors: 5; number of stairwells: 4; number of occupant: 200; average daily water consumption for flushing toilets: 35 dm3.

Simulation calculations were carried out with the use of archival data concerning twentyfour hour precipitation for a period of 10 years observed in Rzeszów town located in southeastern part of Poland. Average annual precipitation in the analyzed period amounted to 612 mm.

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Other parameters of the simulation model adopted for calculations:          

average demand for water for specific purpose in time interval per inhabitant Vd = 4.67 m3/day (24hrs); roof surface F = 1,000 m2; average coefficient of rainwater flow from the roof surface area ; storage tank capacity (5 options): Vt1 = 5 m3 Vt2 = 10 m3, Vt3 = 15 m3 , Vt4 = 20 m3, Vt5 = 30 m3 ; purchase price for 1 m3 municipal water, cw = 0.94 EUR; purchase price for 1 kWh of electric power (according to tariff for households), ce = 0.1159 EUR; discount rate for analyses in fixed (r = 0.05) and variable prices (r = 0.08); capital investment for RWUS, INVk,: INV1 = 8,080 EUR, INV2 = 8,750 EUR, INV3 = 9,500 EUR, INV4 = 10,250 EUR, INV5 = 11,700 EUR. annual maintenance costs for each of k RWUS variants, Cck = 50 EUR/year; investment life cycle, T = 30 years.

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In the research work, a possibility of municipal water price changes in the future was also taken into account. For that reason, a forecast concerning municipal water price changes within the investment realization period was elaborated on the grounds of archival data for a 12-year season. Results of the forecast are presented in Figure 2.

Figure 2. Archival data from 1997–2009 and municipal water price forecast for the years 2010–2039.

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4. RESULTS AND DISCUSSION The model output data obtained as a result of simulation and determining the system‘s economic effectiveness prove unambiguously that in conditions prevailing in Poland, implementation of RWUS in the analyzed multi-family building would not bring the effect expected from the investor‘s point of view, i.e. real economies in scope of the building operation costs. The amount of rainwater used in the building (Table 1) and the resulting municipal water savings at relatively low prices of water purchased from municipal systems in Poland do not compensate RWUS-related investment and operation costs. Table 1. Amount of rainwater used in the building depending on the system variant (tank capacity) Variant k Vt, m3 VRavk, m3

1 5 252.5

2 10 328.6

3 15 366.3

4 20 389.8

5 30 418.9

The period of return of incurred outlays SPBk for different storage tank capacity variants turns out to range from about 19 years for a tank with Vt = 30 m3 to about 28 years for a tank with capacity of Vt = 5 m3 and is close to the technical service life of the whole system (Table 2).

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Table 2. RWUS’s economic effectiveness indicators for fixed municipal water prices Variant k SPB, years NPV, EURO IRR, %

1 27.9 -4,848 -2

2 21.9 -4,396 -1

3 20.1 -3,865 0

4 19.3 -4,949 -1

5 18.8 -5,913 -1

Results of the financial analysis performed for both fixed municipal water prices (Tab. 2) and variable prices forecasted on the grounds of archival data (Tab. 3) indicate that the most favorable system solution (bringing lowest losses in real terms) is the variant with the 15 m3 tank. Table 3. RWUS’s economic effectiveness indicators for variable (forecasted) municipal water prices Variant k NPV, EURO IRR, %

1 -4,476 +1

2 -4,021 +2

3 -3,487 +4

4 -4,546 +3

5 -5,478 +2

For all system variants, negative figures for the Net Present Value were obtained and the Internal Rate of Return value below the adopted fixed and variable discount rates. Therefore, none of the analyzed system variants should be recommended for application to the investor Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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for purely economical reasons as all of them would inevitably result in depletion of his financial means. However, other (non-financial) reasons should be considered for which such system could be implemented in the building.

CONCLUSION Based on analyses performed here, one can formulate the following general conclusions. 





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

Construction of RWUS, despite significant rainwater quantity potential, is not necessarily related with financial effects that could be satisfactory to an investor; that is especially true in the case of countries such as Poland, where municipal water prices are relatively low. The financial result can be improved by enlargement of rainwater acquisition surface area, as well as an increase of storage tank capacity and use of rainwater for other purposes such as, e.g., irrigation, washing, etc. Implementation of a RWUS may be driven not only by purely economic arguments. In some cases, non-economical reasons may prove to be more important, such as, e.g., shortage of water resources, environmental factors, etc. Popularity of rainwater utilization in the construction industry in Poland and other countries with low water purchase prices where implementation of RWUS is not profitable can be increased by means of different subventions and incentives offered by local governments and related to investing in alternative water supply sources, reduction of rain wastewater volume, etc.

REFERENCES Chilton J. C., Maidment G. G., Marriott D., Francis A. and Tobias G. Case study of a rainwater recorvery system in a commercial building with a large roof. Urban Water 1 (4), 345-354, 1999. Dixon A., Butler D., Fewkes A. Water saving potential of domestic water reuse systems using greywater and rainwater in combination. Wat. Sci. Tech. 5 (39), 25-32, 1999. Fewkes A. The use of rainwater for WC flushing: the field testing of a collection system. Building and Environment 34 (6), 765-772, 1999. Ghisi E., Mengotti de Oliviera S. Potential for potable water savings by combining the use of rainwater and greywater in houses in southern Brazil, Building and Environment 42 (7), 1731-1742, 2007. Ghisi E., Montibeller A., Schmidt R. W. Potential for potable water savings by using rainwater: An analysis over 62 city in southern Brazil. Building and Environment 41 (2), 204-210, 2006. Makowski M. A structured modeling technology. European Journal of Operational Research, Vol. 166, Issue 3, 615-648, 2005. Sazakli E., Alexopoulos A., Leotsinidis M. Rainwater harvesting, quality assessment and utilisation in Kefalonia Island, Greece. Water Res. 41 (9), 2039-2047, 2007.

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Słyś D. Potential of Rainwater Utilization in Residential Housing in Poland. Water and Environmental Journal, Vol. 23 Issue 4, 318-325, 2009. Vaes G., Berlamont J. The effect of rainwater storage tanks on design storms. Urban Water 3 (4), 303-307, 2001. Villarreal E. L., Dixon A. Analysis of a rainwater collection system for domestic water supply in Ringdansen, Norrköping, Sweden. Building and Environment 40 (9), 1174-1184, 2007. Zaizen M., Urakawa T., Matsumoto Y., Takai H. The collection of rainwater from dome stadiums in Japan. Urban Water 1 (4), 355-359, 1999.

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Chapter 14

RAINWATER USES AND STORAGE Olanike O. Aladenola Department of Bioresource Engineering, Macdonald Stewart Building, McGill University Macdonald Campus 21,111 Lakeshore Road Ste Anne de Bellevue , Qc, H9X 3V9, Canada

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ABSTRACT Rainwater harvesting (RWH) has been in existence for a long period of time, it precedes the large scale public water systems. It is becoming more popular as world-wide pressure on water resources is mounting due to rapidly increasing populations and changing climate. Rainwater has been identified as potential water source that can be used for activities requiring low water quality. Rainwater harvesting reduces stormwater runoff and dependence on potable water, it lowers the costs and energy associated with treating and pumping water in centralized water supply systems. Rooftop rainwater harvesting provides water for household, industries and public facilities. RWH is promoted in various countries through policies and efforts to reduce the cost of rainwater storage tanks. Local cheap construction materials have been tested and found suitable for constructing rainwater storage tanks. However the cost of rainwater storage tank that will meet all non potable needs cannot be afforded by household in developing countries.

Keywords: Rainwater harvesting, storage tanks, uses

1.1. INTRODUCTION Water is vital to people‘s life and well being as it is essential for daily needs. It is used for domestic, industrial and agricultural purposes. Water supply all over the world is becoming limited as a result of rapidly increasing population, urbanisation and potential impact of 

Email: [email protected]

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climate change among other reasons. In the year 2000, 86% of the 1.2 billion people that lacked access to improved water sources were rural dwellers (WHO, 2004). It is also reported that only 61% of people in developing countries have access to adequate water supply while 36% had access to sanitation facilities (WHO, 1998). Food and Water Watch (2007) reported that 1 in 6 (equivalent of 1.1 billion) people worldwide lack access to clean water. Countries in the Organisation for Economic Co-operation and Development (OECD) group have high average daily water consumption when compared with developing, low income and poor countries. Average daily water consumption per person in United States is approximately 575 litres, Canada uses 335 litres and water consumption in most European Countries ranges from 200 – 300 litres (Project Blue, 2008) while in developing countries, water use ranges from 10 litres (Mozambique) to 175 litres (Peru). Like many developing countries, Nigeria with a population of over 140 million people (NPC, 2006) can not satisfy its domestic water needs and only 47% of the total population have access to water from improved sources in 2007 (WHO/UNICEF JMP; 2008). The burden of water collection in Nigeria is mostly borne by women and girls who are traditional drawers of water. They trek for 20 – 30 minutes and spend between 4 - 5 hours on queue everyday to collect water (Figure 1).

Figure 1. Water collection from a public tap in Akure, Nigeria.

Many countries manage water use by reducing water demand through technologies that increase household water use efficiency or use cheap water source such as rainwater to meet some of their needs. Even countries with adequate water supply are increasingly seeking means of conserving their potable water supply by using rainwater and grey water to satisfy needs that requires low quality water. Rainwater harvesting (RWH) refers to the ancient practice of collecting rainwater from rooftops, land surface or rock catchments. Rainwater harvesting technology has been greatly improved over the years to make it safer for use. Rainwater harvesting is popular in Gansu province China, Brazil, Australia, Kenya, Sri

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Lanka, Uganda, Tanzania, Botswana, Bermuda, Indonesia, Thailand, Singapore, Island of Hawaii in United States and others. Public facilities in Japan (Zaizen et al, 1999), Millennium dome in London (Chilton et al., 1999 and Hills et al., 2001) and Berlin in Germany (UNEP, 2002) uses rainwater on a large scale. It is mandatory to have a rainwater harvesting system for a building plan in New Delhi and Chennai, India in order to secure building approval from the local authority (UNHABITAT 2005). In Bangladesh, rainwater provides a safer water option because of the high level of arsenic concentration found in most of their wells. Rainwater has been reported to promote potable water savings in buildings (Appan, 2000; Fewkes, 1999; Handia et al., 2003; Herman and Schimda, 1999). Rainwater can be used to provide water for toilet flushing, laundry, landscape watering etc. It was reported in the interim report prepared by Toronto and Regional conservation in 2008 that supplementing potable supplies with rainwater can reduce water bills by as much as 50% in homes and up to 80% in industrial buildings. A study by Aladenola and Adeboye (2009) showed that collected rainwater in south west Nigeria can satisfy annual household non-potable needs provided there is adequate storage. The storage unit of the rainwater harvesting system is the most expensive, thus any effort to reduce the cost is desirable and would promote rainwater harvesting. Cost reduction in storage units could be achieved by using cheap local materials for construction and choosing appropriate design that eliminates waste among other things. Governments can also provide subsidies and loans to aid the purchase of storage tanks in countries where residents cannot afford it. Indigenous storage unit tanks that have been used in the past include pumpkin tank, ferro-cement tank, thai jar, plastic lined tank and wattle and daub. These tanks have been produced from various cheap local materials such as mud bricks, stabilized soil, rammed earth, bamboo and tarpaulin. Gmelina arborea sawdust mixed with cement in a ratio of 1: 3 for construction of storage tanks was also suggested by Aladenola et al., 2008.

1.2. RAINWATER HARVESTING TECHNOLOGY Rainwater harvesting is a simple technology that does not require complex engineering designs. It is cheap, decentralized and can be managed according to household needs. Buildings should be designed with the intent of collecting rainwater so that the conveyance systems and probably the storage tanks can be put in place at the same time to avoid additional cost of installing the structures to existing buildings. Examples of rainwater harvesting for urban and rural water use is shown in figure 2a and 2b. A major disadvantage of rainwater harvesting is the initial and change in quality over time, possibility of contamination and limitation of the storage capacities due to cost and space. Low storage capacities will limit rainwater harvesting so that the system may not be able to provide water in a low rainfall period. Increased storage capacities add to construction and operating costs and may make the technology economically unfeasible, unless it is subsidized by government.

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www.zianet.com/tijeras/rainwater_harvesting.htm.

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Figure 2a. Rainwater Harvesting for urban water supply

UNEP/Khaka (Rainwater harvesting: A lifeline for human well-being, p44)

Figure 2b. Rainwater Harvesting for rural water supply

1.3. DESIGN CONSIDERATIONS FOR RAINWATER HARVESTING SYSTEM RWH systems designs depend on the scale of the system. Design is the process of preparing specifications on type, make and proper measurement in constructing structures. Rainwater harvest systems should be designed with a reasonable probability that the system

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will perform its intended function very well for most of its entire design life and the materials used is important for the practicability of the rainwater use. The design of rainwater storage tank is not merely an abstract engineering problem; it is related to the type of assistance, the sort of materials and other resources that are locally available. The three important decisions that a designer will be faced with are: the collection area which is a predefined area where precipitation falls usually on a roof area, what storage method and size should be used and how problems associated with storage tank should be avoided.

1.4. ROOFING MATERIALS FOR RAINWATER COLLECTION Roofing material is an important factor to consider in rainwater collection. As the rooftop is the main catchment area, the amount of rainwater collected depends on the area of the roof while the quality depend on type of roofing material and what lands on the roof from the surrounding environment. Gould (1992) reported that reasonably pure rainwater can be collected from roofs constructed with galvanized corrugated iron, aluminium or asbestos cement sheets, tiles and slates. Roof catchments should also be cleaned regularly to remove dust, leaves and bird droppings so as to maintain the quality of the rainwater.

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1.5. CONVEYANCE SYSTEMS Rainwater is collected from rooftops via the gutters into the storage tanks. At the beginning of the rain, it is important to ensure that the first flush is channeled through the flush diverter in order to prevent dust and debris from collecting in the tank. This is done by closing the valve to the storage tank for the first 5-10 minutes and then opened so that relatively clean water can be collected, if diverters are not available, a detachable down-pipe can be used manually to provide the same result. The storage tanks should have adequate enclosure to minimize contamination from human, animal or other environmental contaminants, and a tight cover to prevent algal growth and breeding of mosquitoes.

1.6. STORAGE TANKS The intended use, supply and demand of the harvested water will determine the type and size of storage structure. The volume of water that can be captured and stored (the supply) must equal or exceed the volume of water used (the demand). Another determinant of the need for storage is the frequency of rainfall. The factors that are considered for designing cheap and affordable tank are water demand, quantum of rainwater that can be harvested, appropriate sizing, optimal shape and materials. Regular maintenance and cleaning of the gutter and storage tank should be carried out. A case study of rainwater harvesting potential in Abeokuta, southwest, Nigeria is presented below. Abeokuta is located in sub-humid tropical region of southwestern part of Nigeria, on Latitudes 7o5` N to 7o20` N and Longitudes 3o 17`E to 3o 20`E with a mean daily temperature of about 28oC and mean annual rainfall of 1156 mm. The household roof area is 80 m2, runoff

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coefficient ranges from 0.80 - 0.85. A minimum of 10 years rainfall data is required to estimate the annual and monthly rainfall average although inter and intra annual rainfall variations is expected. Many estimation of rainwater harvesting potential uses averages of rainfall depths, it is important to note that average or mean rainfall depth does not give a good representation of year-to-year reliability of rainfall supply in a given area because of changing climatic conditions, certain year can be very wet, while others can be normal or dry. However rainfall averages is good enough to design rainwater storage tank size since water demand by users is a major factor considered in sizing of tanks. The volume of rainwater that could be harvested per household (Monthly/Annual) was determined by using equation 1 (Aladenola and Adeboye, 2009).

VR 

R  H RA  RC 1000

(1)

where, VR  Volume of rainwater per household (m3), R  rainfall depth (mm), H RA = household roof area (m2) and RC  runoff coefficient (no unit). Average rainfall depth for September (Month with highest rainfall) R – 192.52 mm Household roof area HRA – 80 m2 Runoff coefficient Rc – 0.80

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Substituting these values into equation 1, Volume of rainwater harvested VR = 12.32 m3 Repeating the above steps for average rainfall depth for January (month with the least rainfall) of 4.67 mm gives a volume of rainwater harvested of 0.30 m3. A total volume of 73.96 m3 can be harvested in a year. This amount is sufficient to meet annual water demand for laundry, toilet flushing and other non potable water use provided there is storage and space. Based on monthly water demand of 2.45 m3 for laundry and flushing, a storage tank of 9.72 m3 is required. This tank cannot be afforded by household in Nigeria and developing countries and therefore a tank that can store rainwater to satisfy a reasonable percentage of their water needs is suggested. Different methods of managing stored rainwater are extensively documented in Thomas and Martinson (2007). To reduce the burden of the cost of the tank, local governments can subsidize the cost of rainwater storage tank.

1.7. RAINWATER QUALITY Rainwater may be contaminated during harvesting, storage and at the point of use. It is also influenced by closeness to polluting sources. Rainwater quality studies revealed that stored rainwater often does not meet WHO guideline standards for drinking water especially

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with respect to microbiological quality criteria due to contamination through contact with the catchment surface (Fujioka and Chinn, 1987; Gerba and Smith, 2005; Lye, 2002; Thomas et al., 2003). However, millions of people in rural areas around the world depend on rainwater for drinking and other domestic purposes without/with few reports of serious health problems. Heyworth (2001) reported that children drinking treated public mains water in South Australia were at an increased risk of gastroenteritis than those drinking rainwater. Wirojanagud et al. (1989) concluded after analyzing rainwater collected from 189 tanks and 416 roof and gutter runoffs in Thailand that rainwater is the safest and most economical source of drinking because its contamination is slight and can be controlled compared to water from other sources. These findings are in contrast to another studies conducted in Australia (Brodribb et. al. 1995) and New Zealand (Simmons and Smith 1997), which established a relationship between rainwater consumption and outbreak of gastrointestinal illness. This shows that no water supply is 100% safe all the time and the main issue becomes what should be the acceptable level of risk, this level is determined based on cultural and socio-economic standards and the quality of alternative water supplies. The chemical compositions of rainwater in Akure southwest, Nigeria are within WHO acceptable limits, the total suspended solids and turbidity levels were very low (< 5 NTU) and the water was visually comparable to that of municipal water (Aladenola et al., 2008). This is in agreement with findings by Ashworth (2005), Meera and Ahammed (2006), Michaelides (1989) and Scott and Waller (1987), although Lead levels exceeding 3.5 times WHO drinking water standards was noted in Selangor, Malaysia (Yaziz et. al. 1989). Aladenola et al. (2008) further stated that natural rainwater may be acidic but pH usually rises during storage especially if cement material is used in tank construction. The issue of rainwater quality is complex as it depends on the prevailing environment, roof material and storage composition. It is therefore important to test the stored rainwater periodically to make sure it is safe.

Wirojanagud et al. (1989) recommended some hygienic practices for the rainwater collection and handling but Gould and McPherson (1987) recommended that rainwater must first be treated before drinking.

CONCLUSION Rainwater harvesting is becoming popular all over the world, it is collected in small barrels or local pots, underground cistern or overhead tank for domestic use. For large public facilities, it is stored in very large tanks. Rainwater offers an additional high quality resource for non potable use thereby reducing the strain on existing potable water supply infrastructures. Rainwater collection will help reduce the burden of collecting water on girls and women who are traditional collectors of household water in developing countries. RWH should be integrated into water policies to increase the use of rainwater. Well designed rainwater harvesting systems with clean catchments and storage tanks supported by good hygiene at point of use can offer drinking-water with very low health risk, whereas a poorly designed and managed system can pose high health risks. The reliability of rainwater is important as it influences the design of collection and storage systems.

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REFERENCES Aladenola, O. O., and Adeboye, O. B. (2009). Assessing the Potential for Rainwater Harvesting Water Resources Management Journal, DOI 10.1007/s11269-009-9542-y. Aladenola, O.O. (2008). Impact of Climate Change on Water Supply in Nigeria, Unpublished Master‘s Thesis Submitted to Vrije Universiteit Brussel and Katholieke Universiteit Leuven Belgium. Aladenola, O.O., Ajayi, A. E., Olufayo, A. A., and Ajayi, B. (2008). Assessment of Gmelina arborea Sawdust-Cement-Bonded Rainwater Storage Tank: The Environmentalist 28: 123-127. Appan, A. (2000). A dual- mode System for Harnessing Roof Water for Non-potable Uses, Urban Water; 1(4):317-21. Ashworth, J. (2005). Roof Collection and Storage of Rainwater for Drinking, Proceedings of the Institution of Civil Engineers (Water Management), 158 (WM4): 183–189. Brodribb, R., Webster, P., and Farrell, D. (1995). Recurrent Campylobacter fetus Subspecies Bacteraemia in a Febrile Neutropaenicpatient Linked to Tank Water, Communicable Disease Intelligence, Vol. 19 pp312-313. Chilton, J. C., Maidment, G. G., Marriott, D., Francis, A. and Tobias, G. (1999). Case study of a Rainwater Recovery System in a Commercial Building with a Large Roof. Urban Water 1(4): 345-354. Fewkes, A. (1999). The Use of Rainwater for WC Flushing: The Field Testing of a Collection System. Building and Environment, 34, 765-772. Food and Water Watch (2007). Betchtel Profits from Dirty Water in Quayaquil, Ecuador. Retrieved April 20, 2010 from http://www.foodandwaterwatch.org. Fujioka, R., and Chinn. (1987). The Microbiological Quality of Cistern Waters in the Tantalus Area of Honolulu, Hawaii, Proceedings of the 3rd International Conference on Rain Water Cistern Systems, Khon Kaen Univ., Thailand, F3 pp1-13. Gerba, C., and Smith, J. (2005). Sources Of Pathogenic Microorganisms and Their Fate During Land Application of Wastes. Journal of Environmental Quality 34, 42–48. Gould, J. and McPherson, H. (1987). Bacteriological Quality of Rainwater in Roof and Ground Catchment Systems in Botswana, Water International, Vol. 12, No. 3. pp135-138. Gould, J.E. (1992). Rainwater Catchment Systems for Household Water Supply, Environmental Sanitation Reviews, No. 32, ENSIC, Asian Institute Of Technology, Bangkok. Handia, L., Tembo, J. M., and Mwiindwa, C. (2003). Potential of Rainwater Harvesting in Urban Zambia, Physics and Chemistry of the Earth; 28 (20-27):893-6. Hermann, T., Schimda, U. (1999). Rainwater Utilization in Germany: Efficiency, Dimensioning, Hydraulic and Environmental Aspects. Urban water; 1(4):307-16. Hills, S., Birks, R., and Mckenzie, B. (2001). The millennium dome ‗Water- cycle‘ Experiment: to evaluate water efficiency and customer perception at a recycling scheme for 6 million visitors. Proceedings of the IWA Second World Water Congress, Berlin 1519 October. Kaumbutho, P. G., and Simalenga, T. E., (eds), (1999). Conservation Tillage with Animal Traction. A Resource Book of the Animal Traction Network For Eastern And Southern

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267

Africa (ATNESA). Harare. Zimbabwe. 173p. A publication supported by French Cooperation, Namibia. Lye, D. (2002). Health Risks Associated with Consumption Of Untreated Water From Household Roof Catchment Systems. Journal of the American Water Resources Association 38(5), 1301-1306. Michealides, G. (1989). Investigation into the Quality of Roof-Harvested Rainwater for Domestic Use in Developing Countries: A PhD Research Study, Proceedings of the 4th International Rainwater Cistern Systems Conference, Manila, Philippines, E2, pp1-12. Meera, V., and Mansoor Ahammed, M. (2006). Water quality of rooftop rainwater harvesting systems: a review. Journal of Water Supply: Research and Technology Aqua 55, 257268. Murray, C. J. L., and Lopez, A. D. (1996). The Global Burden of Disease. A comprehensive Assessment of Mortality and Disability from Diseases, Injuries and Risk Factors in 1990 and Projected to 2020. Harvard School of Public Health on Behalf of the World Health Organisation and the World Bank (Cambridge, MA). NPC, (2006). Population Census of the Federal Republic of Nigeria: analytical report at the national level. National Population in the Commission, Abuja, Nigeria. Project Blue (2008). Roots and Shoots Water Campaign. L‘Institut Jane Goodall Institute Performance Evaluation of a Rainwater Harvesting System 2008. An interim report prepared by: Toronto and Region Conservation Authority under the Sustainable Technologies Evaluation Program Toronto, Ontario. Toronto and Region Conservation Authority. Scott, R., andWaller, D. (1987). Water Quality Aspects of a Rainwater Cistern System in Nova Scotia, Canada, Proceedings of the 3rd International Conference on Rain Water Cistern Systems, Khon Kaen Univ., Thailand, F1 pp1-16. Simmons, G., and Smith, J. (1997). Roof Water a Probable Source of Salmonella Infections, New Zealand Public Health Report, Vol. 4, No. 1. pp5. Thomas, T. H., and Martinson, D.B. (2007). Roofwater Harvesting: A Handbook for practitioners. Delft, The Netherlands, IRC International Water and Sanitation Center. (Technical Paper series, no.49). 160pp. Thomas, F., Bastable, C., and Bastable, A. (2003). Faecal Contamination of Drinking Water During Collection and Household Storage: The Need To Extend Protection to The Point of Use. Journal of Water and Health 1(3), 109-115. United Nations Environmental Program-DTIE-EITC/Sumida City Government/ People for Promoting Rainwater Utilization (2002): Rainwater harvesting and utilization; An Environmentally Soundly Approach for Sustainable Urban Water; An Introductory Guide for Decision Makers. UN-HABITAT, (2005) Blue Drop Series on Rainwater Harvesting and Utilisation, UNHABITAT, Nairobi, Kenya (2006) Meeting Development Goals in Small Urban Centres– Water and Sanitation in the World‘s Cities 2006. Wirojanagud, W., and Hovichitr, V. et al., (1989). Evaluation of Rainwater quality: Heavy Metals and Pathogens, IDRC, Ottawa. World Health Organization (WHO), (1998). Division of Control of Tropical Diseases. Homepage online: http://www.ch/ctd. World Health Organization (WHO), (2004). Water, Sanitation and Hygiene Links to Health: Facts and Figures, Updated March, 2004.

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Olanike O. Aladenola

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WHO/UNICEF, (2004). ―Improved Drinking Water, Thailand Coverage Estimates‖, Joint Monitoring Programme for Water Supply and Sanitation, WHO/UNICEF July, 2004. WHO/UNICEF JMP, (2008). Federal Republic of Nigeria: Improved Water Coverage Estimates (1980–2006). Joint Monitoring Programme. Yaziz, M., Gunting, H., Sapiari, N., and Ghazali, A. (1989). Variations in Rainwater Quality from Roof Catchments, Water Research, Vol. 23, pp761-765. Zaizen, M., Urakawa, T., Matsumoto, Y., and Takai, H. (1999). The collection of rainwater from dome stadiums in Japan, Urban Water, 1(4):335-359.

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INDEX

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A abatement, 94 abolition, 221 absorption, 69, 78, 204, 210, 214 abstraction, 117, 121, 122 accountability, 153 accounting, 130 accuracy, 21, 158, 168 acetaminophen, 184, 185 acetic acid, viii, 83, 85, 86, 94 acid, vii, viii, ix, 76, 83, 84, 85, 86, 87, 88, 89, 92, 94, 95, 97, 100, 101, 102, 103, 104, 105, 106, 186, 195 activated carbon, 194 adaptation, 3, 30, 33, 36, 38, 46, 74, 81, 155, 158 adhesion, 70, 103 adjustment, 63, 109, 130, 150, 153 adsorption, 165, 171, 194 advantages, 51, 84, 113, 200, 220, 226, 238, 240, 245 Africa, v, ix, 18, 20, 21, 32, 36, 37, 38, 55, 107, 108, 109, 110, 112, 113, 114, 115, 119, 121, 122, 124, 231, 249, 267 agencies, 112, 113, 114, 115, 119, 120, 128, 151, 157, 169 agricultural sector, 118, 154 agriculture, vii, viii, 1, 2, 3, 4, 21, 30, 33, 34, 35, 36, 37, 38, 41, 45, 46, 54, 56, 57, 64, 71, 73, 78, 82, 92, 95, 96, 101, 104, 105, 118, 121, 123, 124, 137, 152, 153, 154, 155, 158, 160, 162, 165, 169, 173, 176, 188, 189, 225, 250 airplanes, 57 Alaska, 231 aldehydes, 84, 100, 101 algae, 100 algorithm, 22, 251 allocating, 158

almonds, 11 aluminium, 85, 263 ambient air, 60, 238, 239 amines, 193 amino acids, viii, 83 ammonia, viii, 83 antibiotic, 185, 192 anti-inflammatory drugs, 185 antipyretic, 185 aquifers, vii, 51, 53, 54, 57, 58, 61, 65, 82, 89, 121, 122, 139, 168, 220, 221, 230 Aral Sea, 176 Argentina, viii, 67 aromatics, 186 arsenic, 214, 261 Asia, 36, 233, 249 assessment, 37, 38, 45, 82, 111, 117, 130, 142, 158, 178, 192, 194, 195, 257 assets, 112 atmospheric pressure, 112 authoritarianism, 146, 151, 152, 153 authorities, 120, 131, 151, 152, 153, 156, 157, 173

B background information, ix, 107 bacteria, ix, 84, 85, 87, 89, 92, 94, 98, 99, 102, 103, 193 Bahrain, 233 Bangladesh, viii, 41, 67, 79, 81, 82, 261 barium, 214 barriers, 120, 221, 222 Beijing, 145, 157, 159 Belgium, 162, 266 belief systems, 117 bending, 204 beneficial effect, 77 bioaccumulation, 99 biodegradability, 182, 189, 202

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Index

270 biological activity, 5 biomass, 22, 26, 32, 34, 36, 189 bisphenol, 84 bleaching, 85 Bolivia, 231 bonds, 87 boreholes, 165 Botswana, 16, 17, 31, 261, 266 boundary conditions, 19, 22 Brazil, 197, 199, 203, 214, 257, 260 Broadcasting, 61 bromine, viii, 83 building blocks, 47 buildings, xi, 249, 250, 261 Bulgaria, 176 Burkina Faso, 15, 18, 30, 32, 39, 108, 114, 115 by-products, viii, 83, 84, 100, 101, 105, 106

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C cadmium, 214 calcium, 70, 77, 198, 202 calibration, 21 campaigns, 46 canals, 51, 60 capacity building, 115, 157 capillary, 56, 70, 172 carbohydrate, 48, 63 carbon, 2, 17, 62, 77, 85, 90, 92, 100, 141, 182, 185, 187, 189, 190 carbon dioxide, 77, 85, 100, 182, 190 carbon emissions, 141 carboxylic acids, 100 cardiovascular disease, 185 case study, 32, 37, 108, 125, 160, 177, 178, 180, 263 cash flow, 253 catalyst, 146, 182, 187 catalytic activity, 185 catchments, 10, 20, 28, 30, 129, 260, 263, 265 cation, 134 CEC, 164 cell membranes, 98 cement, 261, 263, 265 Census, 267 ceramic, xi, 197, 198, 199, 200, 201, 204, 207, 208, 209, 210, 211, 212, 214, 215 Chad, 108, 110, 115 chemical stability, 182, 186 Chile, vii, 1, 4, 16, 20, 23, 24, 25, 29, 31, 34, 36, 37, 114, 122, 231 China, ix, 3, 8, 15, 16, 28, 34, 38, 39, 114, 118, 123, 145, 146, 147, 149, 150, 151, 152, 158, 159, 160, 176, 192, 231, 260

chlorination, viii, xi, 83, 84, 85, 86, 100, 102, 103, 132, 135, 136, 197, 198, 202 chlorine, viii, 83, 84, 85, 94, 99, 101, 102, 103, 104, 135 cholera, viii, 83 chromium, 214 chromosome, 240, 241 circadian rhythm, 186 City, 132, 134, 135, 136, 139, 140, 143, 171, 267 clarity, 186 class, 15, 16, 68, 73, 214 clay minerals, 70, 164, 202, 205, 206 cleaning, 117, 263 clients, 113 climate, vii, ix, x, xi, 1, 2, 3, 4, 18, 19, 23, 27, 28, 29, 30, 33, 36, 38, 41, 44, 65, 78, 81, 108, 115, 127, 128, 129, 131, 141, 145, 148, 150, 155, 156, 158, 159, 163, 171, 219, 232, 250, 259, 260 climate change, vii, xi, 1, 2, 3, 4, 27, 28, 29, 33, 36, 38, 108, 129, 131, 141, 148, 158, 159, 219, 232, 260 CO2, 97, 173, 187, 190 coal, 135, 190 commodity, xi, 219, 220, 221, 222, 223, 224, 226, 227, 228, 233, 236 community, ix, 32, 105, 111, 113, 117, 123, 127, 129, 130, 131, 133, 138, 139, 141, 153 community support, 133 comparative advantage, 226 compatibility, 50 compensatory effect, 63 competition, 28, 62, 129, 134, 195 complexity, 112, 156, 169 compliance, 94, 232 composition, 30, 78, 198, 199, 200, 202, 204, 205, 206, 265 compost, 14 compounds, viii, x, 61, 83, 84, 99, 100, 181, 182, 183, 185, 186, 188, 189, 190, 192, 198, 202, 203 computer simulation, 19 conditioning, xi, 237, 245 conductance, 17, 66 conductivity, 5, 19, 20, 31, 54, 168 conservation, vii, xi, 30, 32, 33, 35, 36, 37, 38, 39, 45, 46, 47, 48, 49, 51, 58, 61, 74, 197, 225, 261 Constitution, 235 consulting, 109 consumption, x, 45, 47, 49, 66, 95, 100, 111, 118, 119, 129, 133, 135, 137, 146, 148, 149, 150, 153, 155, 157, 161, 162, 168, 185, 198, 202, 220, 222, 224, 225, 226, 228, 236, 238, 239, 242, 243, 245, 250, 251, 254, 260, 265 consumption rates, 185

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Index contact time, ix, 84, 88, 91, 92, 93, 94, 96, 99 contaminant, 168 contamination, x, 94, 109, 111, 132, 161, 162, 163, 168, 169, 170, 171, 174, 175, 178, 179, 181, 185, 188, 198, 234, 261, 263, 265 contour, 8, 9, 13, 56 controversies, 134 convergence, 240, 241 cooling, ix, xi, 84, 137, 204, 237, 238, 239, 241, 242, 243, 244, 245, 247 coordination, 122, 151 copolymers, 61 copper, 85, 98, 103 correlation, 212, 214 correlation coefficient, 212, 214 corrosion, x, 99, 161, 172 corrosivity, x, 161, 163, 177 corruption, 122 cosmetics, 191 cost, xii, 4, 18, 28, 34, 47, 48, 49, 51, 53, 82, 84, 85, 95, 98, 110, 122, 129, 133, 139, 154, 170, 172, 182, 191, 198, 199, 200, 238, 254, 259, 261, 264 cost saving, 48 cotton, 163, 165, 170, 179 covering, viii, 14, 41, 58, 150 crop production, viii, 3, 9, 10, 11, 17, 27, 28, 33, 36, 41, 55, 56, 62, 66, 80, 162 crop rotations, 29 crops, 2, 4, 5, 9, 11, 12, 13, 16, 17, 18, 22, 34, 42, 47, 48, 54, 56, 57, 59, 60, 62, 63, 64, 71, 72, 73, 74, 76, 77, 78, 80, 81, 114, 118, 128, 162, 170, 173, 226, 227 crystalline, 205 crystallinity, 195 cultivation, 14, 48, 226 cultural practices, 63, 80 culture, 48 current limit, 152 cycles, vii, 1, 2, 70 cycling, 34, 35, 159 Cyprus, 223, 233 cyst, 84

D damages, i183, 190, 191 danger, 171, 190 DBP, 84 decay, 87, 88, 94, 103 decentralization, 120 decision-making process, 21 decomposition, 26, 77, 88, 100 defects, 208 deficiencies, 42, 226

271

deficiency, 149, 153, 234 deficit, viii, 41, 44, 48, 56, 62, 63, 66, 159, 176, 220, 250 deflation, 51 degradation, viii, 2, 58, 61, 63, 65, 67, 83, 100, 103, 162, 171, 175, 176, 179, 185, 186, 187, 188, 189, 190, 192, 193, 194, 195, 198 degradation rate, 171, 189, 190 delegates, 151 democracy, 128 denaturation, 87 Denmark, 1, 162, 178, 179 Department of Agriculture, 43, 72, 82, 159 deposition, 10 deposits, viii, 67, 68, 79, 171, 173 depression, 139 derivatives, 186, 189, 190 desorption, 165, 171, 178 destination, 233 destruction, 109 detection, 47, 170, 178, 193 detention, 12 developed countries, 227 developed nations, 153 developing countries, xii, 35, 107, 109, 120, 227, 259, 260, 264, 265 diagnosis, 69 dichotomy, 151, 153 differential treatment, 227 diffraction, 204 diffusion, 84 direct measure, 21 disadvantages, 44, 220 discharges, 128, 129 discrete variable, xi, 237 discrimination, 225 disinfection, vii, viii, ix, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 132, 135, 136 dispersion, 13, 71, 84, 209 distillation, 223 distilled water, 186 diversity, ix, 127, 128, 131, 137, 227 DNA, 98, 191 Doha, 226, 227 dominance, 70 dosage, 187 drainage, x, 21, 23, 55, 57, 76, 79, 139, 161, 163, 164, 171, 172, 176, 177 drinking water, ix, x, 84, 85, 105, 114, 115, 123, 127, 128, 129, 131, 132, 133, 136, 138, 139, 140, 141, 153, 162, 168, 171, 181, 183, 264, 265

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Index

272

drought, 3, 23, 35, 41, 42, 43, 44, 45, 46, 57, 62, 63, 64, 66, 108, 113, 129, 131, 133, 139, 146, 150, 154, 226 drugs, 182, 183, 184, 185, 186, 191 dry matter, 89 drying, 48, 53, 63, 66, 71, 150, 198, 199, 202, 204, 208 dumping, 92 dyes, 98, 186, 187, 191, 193

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E E.coli, 88, 92, 98 early warning, 43 ecology, 141 economic development, x, 45, 108, 110, 118, 122, 145 economic efficiency, 46, 74 economic evaluation, 21 economic growth, 197 economic resources, 250 economy, 57 ecosystem, 51, 148, 150 Ecuador, 266 educational background, 28 EEA, 178, 179 Efficiency, 59, 153, 266 effluent, 57, 90, 91, 92, 94, 95, 96, 100, 103, 104, 105, 111, 114, 118, 128, 129, 133, 134, 135, 137, 172, 178, 186, 187, 188, 189, 193, 194 effluents, 61, 89, 90, 91, 92, 93, 94, 95, 96, 97, 101, 103, 104, 118, 133, 185, 186, 187, 188, 190, 191, 193, 195 egg, 89 Egypt, 3, 32, 250 electrical conductivity, 68, 69, 73, 174 electricity, 141 electron, 86, 178, 204 electron microscopy, 204 elongation, 56 employment, 112 encapsulation, 214 encoding, 240 encouragement, 235 endocrine, 84, 102 endowments, 117 energy consumption, 238, 239, 245, 246 energy efficiency, 238 enforcement, 225 engineering, ix, 62, 64, 102, 107, 108, 216, 244, 261, 263 enlargement, 257 environmental awareness, 128 environmental conditions, 81

environmental degradation, 2 environmental effects, 170 environmental factors, 257 environmental impact, 46, 169, 178, 198, 232, 236 environmental protection, 2, 35, 46, 74, 137, 151, 226 Environmental Protection Agency, 178, 190, 195 environmental quality, 162 environmental regulations, xi, 197, 198 environmental resources, 65 environmental risks, 220 environmental sustainability, 123 enzymes, 87 EPA, 178, 190, 195 epoxy resins, 85 equilibrium, 81, 88, 101 equipment, 51, 86, 175, 251, 253 equity, 46, 74, 149, 157 erosion, 2, 5, 9, 10, 14, 31, 35, 36, 71, 140, 188 ETA, 216 ethics, 117 EU, 169, 178 European Union, 169 evaporation, viii, 2, 3, 7, 8, 14, 27, 29, 41, 56, 58, 59, 60, 67, 77, 79, 148, 163, 171 evapotranspiration, 7, 44, 58, 60 exclusion, 224 exercise, 120, 226 expenditures, 122 experiences, 35, 113, 151, 157 exploitation, 45, 109, 149 explosives, 190 exports, xi, 219, 220, 221, 222, 224, 225, 226, 228, 230, 231 exposure, 188 externalities, 129 extinction, 240 extraction, 52, 143, 178, 199, 220, 223, 228

F factories, 154 faith, 235 famine, 108, 222, 223, 227, 228 farmers, x, 10, 18, 28, 30, 32, 33, 47, 63, 80, 81, 107, 121, 135, 138, 161, 173, 223, 232 farming techniques, 59 farms, viii, 28, 36, 41, 137, 170 faults, 165 ferric ion, 183 ferrous ion, 182, 191 fertility, 17, 18, 24, 31, 32, 63, 64, 123 fertilization, 78, 168, 176

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Index fertilizers, x, 64, 78, 123, 161, 162, 168, 169, 173, 175, 176, 188 fetus, 266 fiber, 119 fibroblasts, 195 filters, 89, 94, 99 filtration, xi, 90, 99, 132, 134, 135, 188, 193, 197, 198, 202 financial resources, 50 financial support, ix, 127 fish, 89, 116 fisheries, 45 fishing, 115 fitness, 241, 244 fixation, 26 flexibility, 155 flocculation, xi, 140, 197, 198, 202 flooding, 53, 139 flotation, 132 fluctuations, 99, 147, 148, 154, 155 fluid, 202 fluorescence, 204 food production, vii, viii, 1, 2, 22, 35, 41, 81, 113, 118, 235 food safety, 227, 234 forecasting, xi, 249 foreign investment, 223 formaldehyde, 190, 191, 195 formula, 87, 253, 254 France, 162 free radicals, 97, 105 free trade, 226 freshwater, 56, 84, 115, 148, 153, 158, 162, 220, 221, 222, 223, 228 friction, 238 friendship, xi, 219 funding, 114, 122, 123, 154

G Ganges River, 232 gastroenteritis, 265 GATT, 221, 222, 224, 225, 226, 229, 230, 231, 234, 235 gel, 61, 202 General Agreement on Tariffs and Trade, 221, 229, 234 genes, 87, 240, 241 genetic diversity, 241 geology, 52, 179 Germany, 54, 261, 266 germination, 56, 72, 77 goethite, 189, 205, 217 goods and services, 113, 236

273

Gori, 105 governance, 153, 156, 157, 159 government policy, 32, 81 grades, 57 grading, 113 grass, 34, 72 grasses, 22, 60, 61 gravity, 59, 254 grazing, 2 Great Lakes, 223, 231 Greece, 219, 223, 233, 257 grouping, 5 growth rate, 66, 88 growth time, 88 guidelines, ix, 119, 121, 127, 138 Guinea, 115, 121

H hardening process, 63 harmful effects, 78 harvesting, vii, xi, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 49, 50, 54, 55, 56, 139, 140, 141, 142, 143, 257, 259, 260, 261, 262, 263, 264, 265, 267 Hawaii, 261, 266 HE, 89, 90 health effects, 142, 191 health problems, viii, 3, 83, 265 heat transfer, 244 heavy metals, 84, 162, 174 height, 48, 81 hemisphere, 167 hepatitis, viii, 83 hepatitis a, viii, 83 heterogeneous catalysis, 195 highlands, 36 Highlands, 231 homogeneity, 213 hostilities, 122 hotels, 113, 114 housing, 49, 132 human capital, 114 human development, 183 Human Development Report, 159 human exposure, 183 human resources, 44 human rights, 232 hybrid, 20, 192 hydrocarbons, 84 hydrogen, viii, 83, 85, 86, 88, 101, 102, 103, 182, 191

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Index

274 hydrogen peroxide, viii, 83, 85, 86, 88, 101, 102, 103, 182, 191 hydrolysis, 192 hydroponics, 137 hydroxyl, 97, 182 hygiene, 265 hypothesis, 128

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I ibuprofen, 184, 185 ideal, viii, 5, 14, 54, 83 illumination, 186, 187 immersion, 204 immune system, 100, 105 immunity, 224 impact assessment, 42 Impact Assessment, 35 impacts, 28, 32, 33, 42, 44, 65, 76, 118, 119, 135, 154, 158, 159, 162, 169 imported products, 224 imports, xi, 50, 219, 220, 221, 224, 225, 228, 230 impurities, vii, 113, 118 increased access, 123 India, viii, 3, 13, 14, 15, 17, 18, 21, 28, 32, 33, 34, 36, 37, 38, 67, 72, 109, 114, 118, 122, 123, 124, 158, 162, 173, 177, 179, 229, 250, 261 indigenous knowledge, 5, 21, 36 Indonesia, 261 industrialization, x, 45, 145, 148 infants, 169 inflation, 47, 49, 51 initiation, 53, 131 insects, 170, 188 insecurity, 220 insomnia, 186 integration, vii, 2, 21, 23, 29, 224 international law, 226 international trade, vii, xi, 219, 220, 221, 222, 223, 224, 225, 226, 228, 229, 230 intervention, 2, 80, 232, 233 intrusions, 135 investors, 223 ions, 67, 98, 173, 175 Iran, 3, 15, 16, 17, 19, 30, 178, 250 Iraq, 162 iron, viii, 81, 83, 165, 183, 185, 186, 187, 189, 194, 195, 198, 199, 202, 203, 205, 206, 214, 263 irradiation, 97, 98, 185, 187, 189, 195 Islam, 233 isomers, 190 Israel, 3, 15, 30, 33, 223 Italy, 179, 199, 230 Ivory Coast, 176

J Japan, 54, 160, 179, 217, 258, 261, 268 Jordan, 3, 13, 15, 16, 30, 35, 223, 233, 235

K Kenya, 3, 18, 19, 31, 32, 33, 34, 37, 108, 121, 125, 260, 267 kinetic model, 87 kinetics, 102, 193 Kuwait, 233

L lakes, x, 42, 49, 58, 92, 115, 116, 118, 122, 152, 181, 182, 183, 198 landfills, 198 landscape, viii, 38, 48, 61, 67, 70, 109, 141, 261 landscapes, 14 leaching, x, 69, 73, 76, 77, 78, 161, 168, 169, 170, 171, 175, 178, 200, 204, 214, 215 legislation, 29, 94, 226, 228 levees, 51, 80 limestone, 165, 166 Limitations, 158 Limpopo, 35 linear programming, 150 liquid chromatography, 193 liquid phase, 102 livestock, 22, 54, 55 living environment, 3 local authorities, 113, 120 local government, 131, 139, 257, 264 logging, 71 low temperatures, 88 Luo, 102 lying, 164

M machinery, 114, 122 magnesium, 17, 70, 198, 202 Maine, 228 majority, 3, 110, 111, 137 Malaysia, 265 management committee, 151, 157 manganese, viii, 83, 165, 214 manipulation, 64 manpower, 122 manufacture, xi, 197, 198, 199, 200, 208, 215, 239 manufacturing, 190, 220 manure, 64, 77 mapping, 71, 240

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Index marketing, 229 matrix, 23 media, 48, 61, 94, 107, 141, 142, 143, 144, 188, 205 median, 44 Mediterranean, 24, 25, 26, 34, 35, 192 Mediterranean climate, 35 melatonin, 184, 186, 193 mercury, 187 metabolites, 190, 192 metals, 172 meter, 168 methanol, 191, 195 methemoglobinemia, 169 methodology, 37, 111, 247 Mexico, 3, 223, 232 microcline, 205, 217 micronutrients, 78 microorganism, 85, 87, 88, 92, 104 microstructures, 210 Middle East, 31, 223, 232, 233, 236 migration, 128, 141 mineral water, 228 mineralogy, 200 mining, 3, 50, 114, 132, 135 Ministry of Education, 145 Miocene, 165, 166 mixing, 74, 75, 81, 203 modeling, 160, 238, 251, 257 modelling, vii, 1, 4, 20, 21, 27, 29, 30, 38, 102 modernization, xi, 249, 250 modification, 81, 103 modulus, 63, 212, 213, 214 moisture, 5, 11, 17, 23, 34, 37, 38, 42, 43, 44, 56, 61, 66, 70, 76, 165, 204 moisture content, 5, 70, 204 molar ratios, 185 molecules, 70, 85, 97, 171, 182 Mongolia, 149, 153, 155 monitoring, 20, 31, 111, 150, 156, 169, 173, 174, 176, 177, 192 Morocco, 199 morphology, 63, 204, 206 mosquitoes, 263 motivation, 53, 115, 117 Mozambique, 260 multiple factors, 81 mutation, 238, 240, 241, 245 mutation rate, 241

N Na+, 76 Na2SO4, 76 NaCl, 13, 186

275

NAFTA, 221, 222, 223, 229, 230, 232 Namibia, 222, 231, 267 natural disasters, 234 natural resources, xi, 121, 142, 197, 200, 220, 221, 222, 224, 225, 226, 227, 230, 234, 235 natural selection, 240 Nd, 88, 89 negative attitudes, 113, 117 Netherlands, 267 New South Wales, ix, 127, 128, 131, 132, 133, 134, 137, 138, 139, 140 New Zealand, 265, 267 next generation, 241 NGOs, 117, 120 Niger River, 115 Nigeria, v, ix, 107, 108, 110, 111, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 237, 260, 261, 263, 264, 265, 266, 267, 268 nitrate, x, 32, 161, 162, 163, 168, 169, 174, 176, 177, 178 nitrates, 70, 176 nitrification, 89, 103 nitrogen, 17, 24, 25, 29, 64, 168, 176, 178, 188, 190 nodules, 165 non-renewable resources, 65, 114 normal distribution, 44 North Africa, 36 North America, 86, 109, 221, 229, 232 North American Free Trade Agreement, 221, 229, 232 nucleic acid, 85 nutrients, 71, 78, 82, 89, 114, 123, 137, 173 nutrition, 76, 78, 225

O oceans, vii, x, 58, 70, 128, 181, 182, 183 oil, 118, 119, 135, 228 oilseed, 18, 54 olive oil, 190, 195 operating range, 238, 244 opportunities, 29, 32, 37, 78, 113, 123, 228, 247 Opportunities, 38, 140 optimism, 122 optimization, xi, 194, 237, 238, 241, 245, 246, 247 optimization method, 245, 246, 247 ores, 136 organic chemicals, 84 organic compounds, ix, 83, 162, 190 organic matter, viii, 14, 21, 24, 25, 26, 29, 56, 64, 83, 84, 96, 164, 165, 186, 202, 206, 208 organism, 87, 191, 195 oscillation, 34 osmosis, 129, 132, 138, 188

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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ownership, 108, 115 oxalate, 187, 189, 193, 194 oxidation, viii, x, 83, 84, 85, 86, 89, 94, 101, 102, 104, 105, 133, 135, 136, 138, 181, 182, 187, 188, 189, 190, 191, 192, 193, 194, 195 oxidative stress, 87 oxygen, 85, 90, 92, 95, 185, 189, 203 ozonation, 84, 85, 102, 132, 182, 191 ozone, viii, 83, 84, 99, 102, 103, 104, 105

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P PAA, viii, ix, 83, 84, 85, 86, 87, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 103, 104, 105 Pacific, 233 Pakistan, viii, 3, 4, 15, 16, 33, 37, 67 paradigm shift, 36 parallel, 112, 132 parity, 98 pasture, 10 pathogens, viii, 83, 89, 90, 102, 123 pathways, 19, 62, 88, 162, 179, 193 pedigree, 22 penalties, 157 per capita income, 49 percolation, 4, 7, 54, 59, 60, 79, 94, 97, 171 performance, 7, 8, 13, 20, 53, 62, 143, 188, 193, 238, 243 permeability, 69, 73, 77, 87 permission, iv peroxide, 85 persuasion, 118 Perth, ix, 127, 129, 130, 136, 137, 138, 140 Peru, 3, 260 pesticide, x, 161, 162, 163, 170, 171, 178, 179, 188, 194 pesticides, x, 161, 162, 168, 170, 171, 174, 175, 176, 182, 188, 189, 194 pests, 64, 188 pH, xi, 17, 26, 27, 68, 69, 71, 85, 86, 90, 92, 94, 95, 135, 164, 168, 185, 186, 187, 188, 191, 197, 198, 202, 203, 265 phagocytosis, 100 pharmaceuticals, 102, 184, 190, 192, 193 phenol, 101, 190, 191, 195 Philippines, 267 phosphorus, 17, 24, 27, 78, 165, 188 photocatalysis, 182, 193 photolysis, 97 photooxidation, 188 photosynthesis, 63 phthalates, 84 physical and mechanical properties, 200 physical properties, 19, 73

physical treatments, viii, x, 83, 197, 198, 202 physical-mechanical properties, 198 pineal gland, 186 pipelines, 60, 133, 223, 232, 233 plants, vii, ix, x, 1, 3, 45, 48, 59, 60, 61, 63, 71, 72, 77, 78, 79, 82, 84, 86, 90, 92, 95, 99, 109, 110, 117, 118, 127, 129, 133, 134, 135, 140, 171, 182, 185, 197, 198, 202, 203, 225 plasticity, 199, 208 plastics, 135, 190 Pliocene, 165, 166, 173 Poland, 249, 250, 254, 256, 257, 258 policy instruments, 157 policy makers, 109 political leaders, 226 pollution, x, 58, 109, 120, 123, 139, 146, 148, 150, 151, 152, 153, 161, 162, 168, 169, 170, 173, 175, 176, 177, 178, 179, 181, 186, 198, 200, 204, 220 polymers, 61 population growth, xi, 45, 119, 148, 158, 219 porosity, 56, 200, 211 potassium, 17, 24, 70, 198, 202 potato, 38, 72 poverty, 120, 158, 159 practical case study, vii, 1 precipitation, vii, xi, 1, 2, 4, 14, 15, 16, 23, 27, 42, 43, 44, 57, 66, 77, 90, 115, 147, 148, 158, 163, 249, 251, 252, 253, 254, 263 present value, 212 prevention, 146, 149, 150, 151, 152, 153, 225 price changes, 255 primacy, 119 primary products, 221 priming, 64 probability, 17, 43, 171, 212, 241, 245, 262 problem solving, 244 producers, 137 productivity, 2, 3, 30, 35, 36, 37, 45, 62, 63, 64, 66, 115, 162, 165, 172, 176, 179 profit, 115, 199, 228 programming, 150, 160 project, 18, 111, 112, 113, 114, 120, 132, 133, 135, 136, 138, 139, 140, 143, 158, 223, 250 proliferation, 100 property rights, 223 proteins, 87 psa, 192 Pseudomonas aeruginosa, 87, 97, 102 public awareness, 46, 48, 121 public health, 172, 199 public interest, 117, 122 public parks, 89 pulp, 187, 194

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

Index pumps, 237, 238, 239, 242, 243, 244, 245 purification, ix, 84, 143

Q Qatar, 233 Quakers, 134 quality of service, 110 quartz, 205, 217 questioning, 134 quotas, 150, 154, 221, 224

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R race, 137 radiation, 102, 103, 182, 185, 187, 204 radicals, 97, 182 radio, 123 rainfall, vii, viii, ix, 1, 2, 3, 4, 7, 8, 10, 11, 14, 17, 18, 19, 20, 22, 23, 29, 30, 36, 38, 41, 42, 43, 51, 53, 54, 55, 56, 70, 79, 80, 81, 112, 122, 127, 128, 131, 134, 171, 261, 263, 264 rangeland, 9, 10, 22 raw materials, 198, 199, 200, 204, 205, 206, 207, 208 reaction rate, 187 reaction time, 187, 188, 189, 191 reactions, 97, 101, 183, 185, 187, 228 real income, 49, 122 real terms, 256 real time, 238 reality, xi, 219, 228 recommendations, iv, x, 8, 145, 146, 158, 250 recreation, 115 recycling, vii, ix, xi, 57, 84, 103, 107, 108, 109, 112, 113, 114, 115, 117, 120, 121, 122, 123, 127, 128, 129, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 153, 197, 198, 199, 200, 215, 220, 266 redistribution, 112 reforms, 154, 156, 159 regeneration, 22, 89 regression, 19, 30, 212 regression model, 19, 30 regrowth, 104 regulatory framework, 221, 222, 223, 224 rehabilitation, 9, 49, 50, 56 rejection, 238, 244 relevance, 84, 122 reliability, 30, 264, 265 remediation, 138, 139, 188, 190, 194 remote sensing, 21, 32, 33, 37 repair, 47, 94, 102 reparation, 85 replacement, 77, 138, 198, 200, 250

277

reproduction, viii, 83, 240 reserves, 223 residues, 17, 56, 64 resistance, 84, 88, 92, 102, 214 resource management, 122, 130, 141, 149, 159 respiration, 173 restaurants, 113, 114 retina, 186 rice field, 80 rights, iv, 130, 141, 156, 223, 232 risk assessment, 138 risk management, 129, 150, 160 river basins, 56, 159 rocks, 68, 70 Romania, 176 roughness, 64 rubber, 51, 52, 55, 58 runoff, vii, viii, x, xi, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 27, 28, 29, 30, 31, 33, 34, 37, 38, 41, 44, 51, 53, 54, 55, 56, 59, 60, 67, 79, 145, 147, 148, 149, 154, 155, 158, 170, 178, 259, 263, 264 rural areas, 114, 122, 137, 148, 152, 265

S salinity, x, 60, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 132, 135, 161, 162, 171, 172, 174, 176, 177, 185, 188 salts, viii, x, 67, 68, 69, 70, 71, 72, 76, 77, 78, 79, 161, 175, 186, 188, 198, 202, 203 saturation, 88, 164, 244 Saudi Arabia, 16, 233 savings, 46, 48, 49, 56, 78, 246, 256, 257, 261 sawdust, 261 scale system, 55 scaling, 35 scanning electron microscopy, 204 scarcity, vii, xi, 2, 4, 29, 35, 36, 84, 108, 109, 110, 116, 118, 120, 154, 155, 157, 160, 219 scheduling, 47, 60, 62 schema, 240 screening, 90, 112 sea level, 81 search space, 245 seasonality, 118 Second World, 266 sectoral policies, 152 sediment, 10, 11, 17, 52, 59, 188 sedimentation, 11, 17, 204 sediments, 111 seed, 61, 62, 64 seeding, 49, 50, 51, 57, 58, 61, 79 seedlings, 77, 78

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

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278

Index

self-interest, 18 self-regulation, 153 SEM micrographs, 206 semicircle, 9 semiconductors, 182 seminars, 123 senescence, 48, 63 senses, 219 sensing, 21, 32 sensitivity, 20, 72, 131 sensitization, 123 sequencing, 63 service life, 252, 256 sewage, vii, x, 57, 58, 61, 86, 104, 105, 106, 109, 111, 112, 118, 128, 129, 134, 145, 192, 251 shape, 212, 263 shock, 61 shoot, 34 shortage, 42, 110, 154, 223, 226, 235, 257 shrinkage, 199, 200, 204, 208, 209, 211 shrubs, 9, 13, 30, 34, 60, 61 Sierra Leone, 115 silica, 205 silicon, 198, 202 silver, 57, 98, 99, 103, 214 simulation, vii, xi, 2, 29, 38, 170, 193, 249, 251, 252, 253, 254, 255, 256 Singapore, 54, 261 sintering, 204 SiO2, 199, 201, 205, 206 skin, 99, 193 sludge, xi, 112, 135, 183, 189, 197, 198, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215 social acceptance, 56 social development, 46, 74 social life, 117, 119 social sciences, 30, 33 social services, 112 socio-economic standards, 265 sodium, viii, 13, 17, 68, 69, 70, 71, 76, 77, 79, 83, 102, 104, 105, 171, 198, 202 soil erosion, vii, 1, 2, 14 soil particles, 70, 71, 171 soil pollution, x, 161 solid waste, 198, 199, 200, 201, 202, 214 South Africa, viii, 20, 21, 30, 31, 67, 70, 108, 109, 110, 111, 112, 114, 118, 231 Southern Africa, 267 Spain, 31, 33, 83, 181 spatial information, 21 specialists, ix, 107 species, 46, 71, 105, 178, 189, 240

specifications, 5, 262 spore, 89, 103 Spring, 229 Sri Lanka, 261 stabilization, 135 stabilizers, 86 stakeholders, 28, 156 starch, 61 steel, 85, 190, 204 stochastic model, 19, 20 stomach, 169 storage, ix, xi, xii, 3, 5, 7, 8, 11, 29, 36, 38, 49, 50, 51, 52, 54, 55, 58, 64, 75, 112, 127, 128, 130, 133, 135, 136, 139, 249, 250, 251, 252, 253, 255, 256, 257, 258, 259, 261, 263, 264, 265 storms, 55, 57, 258 stormwater, xi, 128, 129, 132, 135, 139, 140, 142, 143, 259 streams, 42, 51, 115, 118, 122 streptococci, 97 structural adjustment, 64 sub-Saharan Africa, vii, ix, 107, 108, 109, 110, 112, 113, 114, 119, 120 subsistence, viii, 2, 41 substitutes, 227 substitution, 48 Sudan, 3, 8, 15, 16, 17, 35, 38, 72, 110 sulphur, 76, 87 Sun, 34 supervision, 120 Supreme Court, 226, 235 surface area, 58, 115, 252, 255, 257 surface layer, 22, 44 surface treatment, 36 surplus, 51, 170 survey, 45, 50, 69, 192 survival, 87, 107, 108, 240, 241 suspensions, 189 sustainability, vii, x, 30, 33, 46, 65, 66, 74, 145, 146, 148, 150, 152, 158, 160, 172 sustainable development, 64, 65, 119, 148, 159, 199, 222, 231, 234 Sweden, 258 Switzerland, 179 symptoms, 42 syndrome, 186 synergistic effect, vii, 1, 4, 14 synthesis, 66, 102, 191 Syria, 3, 16, 17, 36, 162, 163, 233, 250

T tanks, xii, 5, 11, 89, 95, 111, 138, 140, 203, 258, 259, 261, 263, 264, 265

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved.

Index Tanzania, 14, 18, 21, 32, 121, 261 tariff, 227, 252, 254, 255 taxonomy, 142 technology transfer, 28 temperature, x, 23, 27, 44, 59, 60, 85, 94, 95, 102, 145, 148, 163, 168, 187, 200, 238, 239, 241, 242, 244, 245, 252, 263 tension, 31, 212 tensions, 60 terraces, 8, 11 territory, 221, 224 testing, 100, 134, 212, 213, 217, 257 textiles, 190, 193 texture, 4, 15, 16, 19, 70, 211 Thailand, viii, 67, 70, 261, 265, 266, 267, 268 thermal analysis, 200 thermogravimetric analysis, 200 tin, 85 tissue, 71 Togo, 121 toluene, 195 total energy, 238, 239 tourism, 118, 121 toxic effect, 98 toxicity, 82, 89, 100, 170, 185, 186, 190, 191, 192, 193, 195 traditions, 108, 117, 121 training, x, 114, 135, 153, 157, 161, 176 traits, 43 transactions, 225, 228 transcription, 102 transformation, 78, 122, 159, 182 transmission, 77 transpiration, viii, 7, 8, 58, 59, 60, 62, 63, 67 transport, 17, 70, 122, 170, 223, 226, 231, 233, 234, 235, 254 transportation, 109, 115, 152, 220, 224 treatment methods, 186 trial, 55, 136 trucks, 232 Turkey, viii, x, 67, 161, 162, 163, 167, 170, 173, 176, 177, 178, 179, 180, 223, 233 Turkmenistan, 3 turnover, 22, 26 typhoid, viii, 83

U UK, 30, 33, 109, 162, 176 ultrasound, 84, 102 UN, 231, 261, 267 UNESCO, 33, 67, 145, 159, 235 uniform, 43, 78 United Kingdom, 102, 229

279

United Nations, 120, 124, 221, 236, 250, 267 United Nations Industrial Development Organization, 250 universities, 111 upward mobility, 115 urban area, 111 urbanisation, 259 urbanization, x, 108, 116, 145, 148, 150, 158 urea, 103 urine, 123, 185 Uruguay, 229 Uruguay Round, 229 USDA, 15, 16, 32, 82, 177 UV, 84, 85, 86, 97, 98, 99, 102, 104, 105, 132, 134, 135, 136, 138, 182, 183, 187, 190, 191, 193 UV irradiation, 98 UV light, 99, 104 UV radiation, 102, 183

V validation, 38 valleys, 12, 20 variations, 49, 72, 115, 117, 150, 154, 200, 203, 264 vector, 240 vegetables, 89, 99, 105, 109, 118, 135 vegetation, viii, 11, 12, 15, 18, 60, 67 vegetative cover, 2 velocity, 11 ventilation, xi, 237 victims, 108 viruses, ix, 83, 84, 85, 89, 99, 102 voters, 228 VSD, 242 vulnerability, 30, 33, 42, 162, 171, 175

W Wales, 131 waste, xi, 46, 54, 89, 94, 100, 112, 133, 135, 183, 194, 197, 198, 199, 200, 201, 214, 215, 261 waste disposal, 198 waste management, xi, 197 waste water, 133 wastewater, vii, ix, x, 46, 84, 85, 86, 88, 89, 90, 91, 92, 94, 96, 98, 99, 101, 102, 103, 104, 105, 106, 108, 109, 110, 111, 112, 113, 114, 115, 117, 118, 119, 121, 122, 123, 124, 128, 129, 132, 133, 134, 136, 137, 139, 142, 178, 181, 182, 183, 185, 187, 188, 190, 191, 192, 195, 257 water absorption, 200, 204, 208, 210, 214 water evaporation, 7 water policy, 159

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,

280

Index World Court, 231 World Health Organisation, 267 World Trade Organization, xi, 219, 220, 221, 222, 224, 226, 227, 228, 229, 230, 231, 234 WTO, 225, 229, 230, 231, 234, 235

X X-ray, 204, 205 X-ray diffraction, 205 XRD, 205

Y Yemen, 3, 31, 36 yuan, 154, 157

Z Zimbabwe, 19, 35, 267

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water quality, x, xi, 12, 50, 54, 77, 78, 92, 102, 113, 152, 161, 163, 178, 188, 203, 250, 259 water quality standards, 152 water rights, 10, 160 water supplies, ix, 2, 13, 17, 42, 57, 107, 108, 117, 121, 122, 127, 128, 130, 131, 141, 169, 265 watershed, 11, 20, 21, 28, 32, 37, 176 watertable, 79 waterways, 139 wavelengths, 183 welfare, 64, 65, 110, 197 wells, 50, 53, 54, 74, 166, 167, 170, 172, 173, 174, 177, 202, 228, 261 West Africa, 34, 115, 121, 124, 231 Western Europe, 176 wetlands, 115, 118, 139 wetting, 63, 71, 78 withdrawal, 50, 81 workers, 28, 132 World Bank, 35, 36, 159, 228, 230, 267

Water Recycling and Water Management, edited by Daniel M. Carrey, Nova Science Publishers, Incorporated, 2010. ProQuest Ebook Central,