Flood Damage Assessment and Management [1st ed.] 9783030500528, 9783030500535

Table of contents :
Front Matter ....Pages i-xiii
Flood Risk Assessment—State of the Art (Martina Zeleňáková, Lenka Gaňová, Daniel Constantin Diaconu)....Pages 1-40
Materials and Methods (Martina Zeleňáková, Lenka Gaňová, Daniel Constantin Diaconu)....Pages 41-91
Application of Methodological Procedures in the Model Territory (Martina Zeleňáková, Lenka Gaňová, Daniel Constantin Diaconu)....Pages 93-117
Conclusion (Martina Zeleňáková, Lenka Gaňová, Daniel Constantin Diaconu)....Pages 119-120

Citation preview

Water Science and Technology Library

Martina Zeleňáková Lenka Gaňová Daniel Constantin Diaconu

Flood Damage Assessment and Management

Water Science and Technology Library Volume 94

Editor-in-Chief V. P. Singh, Department of Biological and Agricultural Engineering & Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX, USA Editorial Board R. Berndtsson, Lund University, Lund, Sweden L. N. Rodrigues, Brasília, Brazil Arup Kumar Sarma, Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India M. M. Sherif, Department of Anatomy, UAE University, Al-Ain, United Arab Emirates B. Sivakumar, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW, Australia Q. Zhang, Faculty of Geographical Science, Beijing Normal University, Beijing, China

The aim of the Water Science and Technology Library is to provide a forum for dissemination of the state-of-the-art of topics of current interest in the area of water science and technology. This is accomplished through publication of reference books and monographs, authored or edited. Occasionally also proceedings volumes are accepted for publication in the series. Water Science and Technology Library encompasses a wide range of topics dealing with science as well as socio-economic aspects of water, environment, and ecology. Both the water quantity and quality issues are relevant and are embraced by Water Science and Technology Library. The emphasis may be on either the scientific content, or techniques of solution, or both. There is increasing emphasis these days on processes and Water Science and Technology Library is committed to promoting this emphasis by publishing books emphasizing scientific discussions of physical, chemical, and/or biological aspects of water resources. Likewise, current or emerging solution techniques receive high priority. Interdisciplinary coverage is encouraged. Case studies contributing to our knowledge of water science and technology are also embraced by the series. Innovative ideas and novel techniques are of particular interest. Comments or suggestions for future volumes are welcomed. Vijay P. Singh, Department of Biological and Agricultural Engineering & Zachry Department of Civil Engineering, Texas A & M University, USA Email: [email protected]

More information about this series at http://www.springer.com/series/6689

Martina Zeleňáková Lenka Gaňová Daniel Constantin Diaconu •

•

Flood Damage Assessment and Management

123

Martina Zeleňáková Technical University of Košice Košice, Slovakia

Lenka Gaňová Technical University of Košice Košice, Slovakia

Daniel Constantin Diaconu Faculty of Geography University of Bucharest Bucharest, Romania

ISSN 0921-092X ISSN 1872-4663 (electronic) Water Science and Technology Library ISBN 978-3-030-50052-8 ISBN 978-3-030-50053-5 (eBook) https://doi.org/10.1007/978-3-030-50053-5 © Springer Nature Switzerland AG 2020 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

The view that floods are a negative consequence of civilization activity which has damaged nature does not have any real professional support in the history of the Earth’s development or in the history of humanity. However, it is true that humans have been transforming ecosystems, changing surface runoff conditions and vegetation composition, spreading urbanization, and disturbing the natural hydrological regime in the landscape for centuries (Krejčí et al. 2002), (Hlavínek et al. 2008). Humanity’s problems with floods began only when, in contrast to their positive effects such as the floods on the Nile in Egypt helping to secure the livelihood of the ancient Egyptian population, floods began threatening the lives, health, and property of the population, and economic activity of developed society (Bačík and Ryšavá 2011). The issue of floods was, is, and will be topical, because as the hydrological community emphasizes, floods cannot be prevented, but people need to learn to live with them. Water simply determines our life whether we have enough, a lack, or a surplus of it (Solín 2006). At present, there are clear trends around the Earth indicating that the risk of flooding will increase in the coming period. The extent and extreme nature of recent flood episodes already points to the necessity of a comprehensive design policy for the building of flood protection structures, and of supplementing existing flood protection measures in potential flood plains (Houghton et al. 2001). Following the floods in Central Europe in the summer of 2002, several member states of the then European Community directed the Council of the EC’s attention to the issue of flood prevention and protection. In October 2004, the Council agreed to their proposal that all member states, coordinated by the European Commission, prepare a European Flood Action Program, which after appropriate legislative processes would become a common, binding legal instrument for all EC member states (Bačík et al., 2006). On October 23, 2007, this initiative led the European Parliament and the Council to adopt Directive 2007/60/EC on the assessment and management of flood risks. The purpose of the Directive was to establish a framework for the assessment and management of flood risks at EC level in order to reduce the adverse effects of floods on human health, the environment, economic activity, and cultural v

vi

Preface

heritage. To achieve its objectives, Directive 2007/60/EC obliged all member states to carry out a preliminary flood risk assessment, to be completed in December 2011, to prepare flood hazard maps and flood risk maps (which were completed in 2013), and to develop flood risk management plans by 2015. Subsequent steps must be updated every 6 years. In order to meet the objectives of the Directive, more and more attention is being paid to risk assessment and analysis methods, as they allow us to assess the cost-effectiveness of mitigation measures and thus optimize investment (Ganoulis 2003; Hardmeyer and Spencer 2007). The analysis is closely related to the classification of each area according to its vulnerability, mathematical modeling of rainfall-runoff processes and water flow in channels, and inundation and damage assessment (Cipovová 2010). In general, most methods for determining potential flood damage used in the world are based on the same principle of application of the loss curve method. They differ only in the manner of expression, detail, and description of the endangered property, and further in the form of the loss curves themselves (Horský 2008). The use of mathematical models and Geographical Information Systems (GIS) in flood management has become a common approach for evaluating and interpreting data. The aim of the deployment of these tools is primarily to accelerate the procedure of processing risk analysis data from flood plains, and subsequently to create flood damage and risk maps. The aim is also to use data sources that are easily accessible, maintained over time, and have a uniform structure for the whole territory. Similarly, multi-criteria analysis has become a commonly used tool in flood management decision-making process as well. This book deals with the issue of flood risk assessment and management with the aim of establishing effective procedures for reducing flood risks and thus increasing the level of flood protection. It has been prepared in accordance with the current legislation in the field of flood protection, in particular, pursuant to the aforementioned Directive 2007/60/EC on flood risk assessment and management. The main aim of the thesis is to extend the scientific knowledge in the field of flood risk assessment and management, and then to propose flood risk management improvements in order to reduce the adverse impacts on human health, the environment, and the economic activity associated with floods. The methods used in this book are based on practical experience as well as knowledge gained from available literature and consultations with experts dealing with the issue in practice. The scientific part of the thesis proposes a methodical procedure for the selection of effective flood protection in order to meet the objectives of flood risk management. The proposal for a procedure for selecting the most cost-effective combinations of measures with a view to reducing the impacts of floods on human health and assets as well as the environment is based on calculations of the loss of human life and environmental and economic damage. This procedure can serve as a basis for the development of flood risk management plans. The calculation of the different categories of damage requires a special approach and different input documents, which are described in Chap. 2.

Preface

vii

The most important information sources and materials used in this work are as follows: • Ph.D. thesis: Flood risk management in selected water flow rivers with regard to the implementation requirements of directive 2007/60/EC (Gaňová 2015); • Ph.D. thesis: Methods of evaluation of potential flood damage and their application by means of GIS (Horský 2008); • Ph.D. thesis: Loss of life estimation in flood risk assessment. Theory and applications (Jonkamn 2007); • Ph.D. thesis: Estimation of the Loss of Human Lives in a Flood (Brázdová 2012); and • Ph.D. thesis: Environmental risks in conditions of selected watercourses in eastern Slovakia (Bendíková 2003). The common objective in the calculations of individual categories of potential flood damage is to determine the levels of environmental, social, and economic risk due to floods (Chap. 2), which serves as a basis for the selection of effective flood protection measures at specific sites. The processing and analysis of the input data as well as the visualization of the results obtained are carried out in the GIS environment (ArcGIS 9.3, 10) integrated with a spreadsheet program (Microsoft Excel). The importance of this work lies not only in providing a current overview of knowledge in the field of flood assessment and management, but also in designing a methodology important for flood risk management and meeting the requirements of Directive 2007/60/EC. The contribution of this work is a comprehensive proposal for a procedure for selecting effective flood protection measures, which can be used to meet the objectives of Directive 2007/60/EC reducing the likelihood of floods as well as their potential adverse consequences. The submitted thesis consists of four chapters. The introduction briefly describes the state of knowledge in this field, assesses the timeliness of the topic, and presents the stated purpose and aim of the work and outlined solution procedure. Chapter 1 provides the main overview of knowledge in the field of flood assessment and management, with an emphasis on possible approaches to assessment, legislation on the issue, and the classification of flood damage. Chapter 2 is devoted to the design of a methodological procedure for the selection of effective flood control measures. The application of the proposed procedure is described in Chap. 3. The conclusions of the research are presented in Chap. 4. Košice, Slovakia Košice, Slovakia Bucharest, Romania

Martina Zeleňáková Lenka Gaňová Daniel Constantin Diaconu

viii

Preface

References Bačík M, Babiaková G, Halmo N, Lukáč M (2006) European legal documents on flood protection and their implementation in the Slovak Republic (in Slovak). Vodohospodársky spravodajca 9– 10 Bačík M, Ryšavá Z (2011) Floods, flood risk management and flood damage (in Slovak). In: Water 2011. Slovak Technical University in Bratislava. http://www.iwa.sk/dokumenty/ prispevky/2011/VODA_2011/PAPER/PDF/01_Bacik.pdf Bendíková M (2003) Environmental risks in conditions of selected watersheds of eastern Slovakia (in Slovak). Dissertation work, TUKE. p 91 Brázdová M (2012) Estimation of loss of human life during flood (in Czech). Dissertation work, FAST VUT v Brně, Brno. p 166 Ganoulis J (2003) Risk-based floodplain management: a case study from Greece. Int J River Basin Manag 1:41–47 Hardmeyer K, Spence, M A (2007) Bootstrap methods: another look at the Jackknife and geographic information systems to assess flooding problems in an urban watershed in Rhode Island. Environ Manag 39:563–574 Hlavínek P et al. (2008) Rainwater management in an urbanized area (in Czech). ARDEC s.r.o., Brno. ISBN 80-86020-55-X Horský M (2008) Methods of evaluation of potential flood damage and their application by means of GIS (in Czech). Dissertation thesis. Prague. p 124 Houghton J T et al. (2001) Climate Change: the scientific basis. Contribution of working group I to the third assessment report of the intergovernmental panel on climate change. WMO and UNEP Solín Ľ (2006) We need to learn to live with floods (in Slovak). Slovak Academy of Science. https://www.sav.sk/index.php?lang=sk&charset=&doc=servicesews&news_no=1022&do= print

Acknowledgements

The authors would like to thank the reviewers for their constructive comments, namely, Prof. Ing. Petr Hlavínek, CSc., MBA—Professor at the Institute of Municipal Water Management, Faculty of Civil Engineering, University of Technology in Brno; Dr. Martin Mišík—expert in flood modeling working for the Danish Hydraulic Institute (DHI Slovakia); and Prof. Dr. Miloslav Šlezingr, Professor at the Institute of Water Structure, Faculty of Civil Engineering, University of Technology in Brno. This work has been supported by the Scientific and Educational Grant Agency of the Ministry for Education of the Slovak Republic under project VEGA 1/0308/20 and through the SKHU/1601/4.1/187 project. The authors would also like to thank the publisher Springer Nature for providing the opportunity for this publication, Andrew Billingham for reviewing the English language, and Eva Singovszka for helping with the formatting.

ix

Contents

1 1 2

1 Flood Risk Assessment—State of the Art . . . . . . . . . . . . . . . 1.1 Assessment of Flood Risk . . . . . . . . . . . . . . . . . . . . . . . . 1.1.1 Basic Concept of Flood Risk . . . . . . . . . . . . . . . . 1.1.2 Methodological Procedures for Flood Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1.3 Approaches to Flood Risk Assessment . . . . . . . . . 1.2 Risk Analysis of Floodplains . . . . . . . . . . . . . . . . . . . . . . 1.2.1 Risk Analysis Methods and Approaches . . . . . . . . 1.2.2 Risk Analysis Tools . . . . . . . . . . . . . . . . . . . . . . . 1.3 Laws on Flood Risk Management . . . . . . . . . . . . . . . . . . 1.3.1 Flood Protection Programs in the EU and Slovakia 1.3.2 Preliminary Flood Risk Assessment . . . . . . . . . . . 1.3.3 Flood Hazard Maps and Flood Risk Maps . . . . . . 1.3.4 Flood Risk Management Plans . . . . . . . . . . . . . . . 1.4 Assessment of Flood Damage . . . . . . . . . . . . . . . . . . . . . 1.4.1 Classification of Flood Damage . . . . . . . . . . . . . . 1.4.2 Factors Affecting the Amount of Flood Damage . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

. . . . . . . . . . . . . .

4 6 10 11 15 21 24 25 26 28 31 31 35 35

2 Materials and Methods . . . . . . . . . . . . . . . . . 2.1 Calculation of Potential Flood Damage . . 2.1.1 Property Damage . . . . . . . . . . . . . 2.1.2 Environmental Damage . . . . . . . . 2.1.3 Loss of Human Lives . . . . . . . . . 2.2 Determining the Level of Flood Risk . . . . 2.2.1 Economic Risk . . . . . . . . . . . . . . 2.2.2 The Environmental Risk of Floods 2.2.3 Social Expression of Risk . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

41 41 43 51 60 69 71 74 74

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

. . . . . . . . .

...... ...... ......

xi

xii

Contents

2.3 Evaluation of the Effectiveness of Flood Protection Measures 2.3.1 Economic Efficiency . . . . . . . . . . . . . . . . . . . . . . . . 2.3.2 Environmental Risk Acceptability . . . . . . . . . . . . . . . 2.3.3 Socially Acceptable Level of Social Risk . . . . . . . . . 2.3.4 Flood Protection Measures . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Application of Methodological Procedures in the Model Territory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Basic Data on the Territory . . . . . . . . . . . . . . . . . . . . . . 3.2 Application of Risk Management Methodology . . . . . . . 3.2.1 Estimation of Potential Flood Damage . . . . . . . . 3.2.2 Flood Risk Calculation . . . . . . . . . . . . . . . . . . . 3.2.3 Selection of Effective Flood Protection Measures . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

77 77 79 79 82 88

. . . . . .

. . . . . .

. . . . . .

. . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. 93 . 93 . 95 . 96 . 112 . 114 . 117

4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

About the Authors

Martina Zeleňáková is Associate Professor in the field of environmental engineering at the Institute of Environmental Engineering, Faculty of Civil Engineering at the Technical University of Košice, Slovakia. In the framework of her scientificresearch activities, she has focused on solution of water management problems; rainwater management; environmental impacts assessment; and separately on the assessment of environmental risks in river basins in relation to flood events, drought, and water pollution. The results of her scientific-research work have been published in national and international journals, scientific conference proceedings, and proceedings of national and international conferences. She is author, editor, co-author, and co-editor of educational textbooks and monographs, and she has cooperated in solving national and international projects, as the principal investigator or partner. Lenka Gaňová graduated Master’s degree and Ph.D. degree in the field of environmental engineering at the Institute of Environmental Engineering, Faculty of Civil Engineering at the Technical University of Košice, Slovakia. Her scientific work as well as her thesis was devoted to flood risk assessment. She was participating in a project implementation regarding the flood protection and she published the results of her research in scientific proceedings of national and international conferences. Daniel Constantin Diaconu works as Assistant Professor at the Department of Meteorology and Hydrology at University of Bucharest, Romania. He does research in hydrology focusing on flood protection, environmental sciences, and integrated water resources management. He is an expert in bathymetry and limnology. The results of his scientific work have been published in journals and conference proceedings. He is participating in scientific projects mainly within Research Center for Integrated Analysis and Territorial Management (CAIMT) within the University of Bucharest.

xiii

Chapter 1

Flood Risk Assessment—State of the Art

Just as floods are one of the extreme manifestations of the water cycle in nature, flood protection is a process that is endless for human civilization. It began in the distant past and will, unfortunately, be with very uncertain results, part of every other stage of the society’s development. Currently, the theme of floods resonates much more than it has been in the past, mainly thanks to the considerable media coverage that contributes to making more people realize this issue. The main reason that led us to choose this theme for the book is that floods are one of the phenomena of contemporary life that affects each one of us and cannot be ignored. Evidence that flood protection and prevention are justified and one of the most important components of land-use planning is damage to property, and even life damage is no exception. The aim of this book is to address the issue of flood risk assessment and management with the aim of effective management aimed at reducing flood risks and thus increasing flood protection. The book is elaborated in the sense of the current legislation in the field of flood protection, in particular, the Directive 2007/60/EC on the assessment and management of flood risk and the Act no. 7/2010 Coll. on Flood Protection, by which the Directive is transposed into Slovak legislation and implemented in the Slovak Republic.

1.1 Assessment of Flood Risk When dealing with flood issues an important task is defining the term “risk.” It should be noted that the issue of risk has evolved and formed in a wide range of different disciplines (crisis management, economics, environmentalism, geography, and sociology), each of which understands and perceives it somewhat differently (Gozora 2000). Although the notion of “risk” is currently a frequently encountered concept, it is characterized by complexity and ambiguity (Mika 2009). This contributes to the fact © Springer Nature Switzerland AG 2020 M. Zeleˇnáková et al., Flood Damage Assessment and Management, Water Science and Technology Library 94, https://doi.org/10.1007/978-3-030-50053-5_1

1

2

1 Flood Risk Assessment—State of the Art

that terms such as “the source of risk,” “the risk factors,” and “the causes of the risk” are confused by many authors, which has also been reflected in the large number of available definitions and considerable opacity existing in the available literature (Tichý 1994; Rozsypal 2003; Šimák 2001; Tichý 2006; Smejkal 2006; Drbal 2008; Zeleˇnáková 2009). According to the definitions given by the authors, risks have their specificities or differences arising from various departments. In general, risk (R) can be expressed as the product of the probability of occurrence (P) and the consequence (C) of a certain event (Bouma et al. 2005; Kandilioti and Makropoulos 2012) (Eq. 1.1): R = P ×C

(1.1)

Hald (1984) states that the oldest definition of risk, which is also the basis for the current understanding of this term, includes the economic definition of risk presented in the work by Abraham de Moivre “De Mensura Sortis” of 1711. Risk is considered to be the risk of the loss of a certain value and its size is expressed by the product of probability and potential loss. As far as flood risk research is concerned, it is multidisciplinary and is of interest to hydrologists, sociologists, economists, environmentalists, and geographers. Each discipline approaches flood risk assessment from its own point of view, which brings with it a certain diversity in the natural expression of flood risk, the terminology, and methodological procedures of its evaluation and management (Solín 2011). An undesirable event, such as a flood, may have a link to particular risk-related loss. The relation of the risk object to undesirable events allows the division of flood risk into (Kandráˇc 2011): • • • • •

individual risk, social risk, environmental risk, economic risk, and other risks.

Each type of flood risk has characteristic sources and factors, the classification of which is given in Table 1.1 Risk arises under certain conditions, if: • there is a risk factor (source of danger/threat), • there is a presence of a given risk factor with a certain level of disposition which is dangerous (or harmful) for objects, and • the object is susceptible to specific activity and risk/threat factors (Kandráˇc 2011).

1.1.1 Basic Concept of Flood Risk The literature describes two basic flood risk concepts, which are described below (Solín and Martinˇcáková 2007; Solín and Skubinˇcan 2013).

1.1 Assessment of Flood Risk

3

Table 1.1 Types of flood risk with respect to the object The type of risk

Object of risk

Unwanted consequences

Social/health risk Individually Human (person)

Illness, trauma, disability, death

Community

Social groups

Group trauma, illness, death of people, increase in mortality

Environmental

–

Ecological systems Damage to water, soil, habitats, protected species

Economic

–

Material resources

Damage to buildings, increased security costs, damage caused by lack of protection

One-dimensional concept The first concept, also referred to as one dimensional (DEFRA 2000), is based exclusively on the application of probability theory. The concept is expanded especially in hydrology, with the term flood risk being used in two meanings. In the first meaning, expressed in relation (1.2) (Solín and Martinˇcáková 2007; Solín and Skubinˇcan 2013): 

1 R =1− 1− T

n (1.2)

where R is the probability with which the annual maximum flow with the average return period T occurs during the following n years (Solín and Martinˇcáková 2007; Solín and Skubinˇcan 2013). In the second meaning formally expressed by Eq. (1.3): F(x) = P(Q ≤ x)

(1.3)

flood risk is the probability (F) that the specified maximum annual flow (x) value is not exceeded in any year. In this context, the frequently used term “return period” expresses the time (number of years) averaged between the recurrence of the specified maximum annual flow (Solín and Martinˇcáková 2007; Solín and Skubinˇcan 2013) in the long term. It is true that (1.4): F =1−

1 T

(1.4)

The greater the probability of occurrence of the specified maximum annual flow rate in any year, the shorter the return period, the greater the flood risk (Solín and Martinˇcáková 2007; Solín and Skubinˇcan 2013). Multidimensional concept The second baseline of the flood risk concept, in addition to the probable occurrence of the specified flood, also takes into account the negative consequences which arise when the flood occurs. It is therefore often referred to as a multidimensional concept

4

1 Flood Risk Assessment—State of the Art

of flood risk (Solín and Martinˇcáková 2007). The multidimensional flood risk concept formally expresses the following definitions: “Flood risk is a combination of flood probability and potential adverse effects on human health, the environment, cultural heritage and economic activity associated with the flood” (Directive 2007/60/EC, Act 7/2010). “Flood risk is a combination of the likelihood or frequency of occurrence of a defined threat and the magnitude of the consequences” (DEFRA 2000). “The flood risk is expressed by the probability of the occurrence of an adverse phenomenon that results in adverse effects on life, health, property or the environment and is defined as n vectors by relation (1.5)” (Drbal et al. 2008; Tichý 1994):

R Ii ≡ (Sci , Pi , Ci ), i = 1, . . . , n,

(1.5)

where Sci scenario of the threat, Pi probability of a threat scenario, and C i consequences (loss, damage) In spite of a certain terminological diversity, the abovementioned risk formalizations share two common components: hazard (probability) and vulnerability (damage).

1.1.2 Methodological Procedures for Flood Risk Assessment The literature survey in the previous chapter shows that flood risk is a product of flood hazard (probability) and vulnerability. Depending on how vulnerability is expressed (from hazard-dependent or hazard-independent vulnerability), the methodology for determining the level of flood risk can be divided into two groups according to Solín (2011): • flood risk expressed in absolute terms, • flood risk expressed in a relative manner. Flood risk expressed in absolute terms The first group consists of methods expressing flood risk in an absolute manner, the expected value of the damage in e. This approach is appropriate for application when assessing vulnerability which is dependent on probability of occurrence. Determining the level of flood risk in an absolute manner includes all expected losses combined with the probability of their occurrence. This means that the flood risk is represented by the area under the damage-probability curve (Fig. 1.1), which represents the total average annual damage (Solín 2011).

1.1 Assessment of Flood Risk

5

Fig. 1.1 Damage probability curve (arranged according to Meyer et al. 2009)

On the discrete scale, the expected value of the total average annual damage (E [X]) is determined by summation (1.6) (Solín 2011): E[X ] =

1 

( pi xi )

(1.6)

n=i

where pi the probability of a flood event occurring, x i the amount of damage caused by the flood event expressed, for example, the amount of damage in e. Flood risk expressed in a relative manner The second group includes methods expressing flood risk in a relative manner, namely, an ordinate scale, which means that dimensionless flood risk values are divided into classes expressing a high, mild, or low level of flood risk. This approach is used to assess vulnerability which is independent of flood probability (Solín 2011). The methodology of flood risk assessment is also significantly influenced by the spatial scale of research (national, regional, or local). The nature of the input data, the processing method, and the accuracy of outputs depend on the spatial level. A suitable method for expressing flood risk in a relative manner is found in spatial Multi-criteria Decision Analysis (MCDA), which is used in the works (Malczewski 2006). The aim of MCDA is to set the overall order of alternatives (spatial units) in terms of flood risk. Spatial multi-criteria analysis is a relatively new and fast-paced

6

1 Flood Risk Assessment—State of the Art

scientific branch, which is still growing especially with the development of GIS systems (Solín 2011).

1.1.3 Approaches to Flood Risk Assessment The need to analyze, evaluate, and manage flood risk requires a clear definition. As a result, a number of methodological approaches have been developed which allow for the risk to be defined, evaluated, and managed. The two main current approaches to risk understanding are termed economic and procedural (Langhammer 2010). Economic Approach The economic approach evaluates risk from the point of view of the consequences of a causal event. The risk rate can usually be expressed according to the relationship (1), which is written as (1.7) (Langhammer 2010): R=F×N

(1.7)

where R represents the risk, F probability of occurrence of a causal event, and N consequences. This approach puts the main emphasis on the consequences of extreme processes and manifestations in the anthropogenic sphere, but less on its own processes and their course. The economic outlook for risk is, for its relative simplicity, the basis for various methods of econometric expression of the degree of risk used in both social and natural sciences. This method of flood risk assessment has been used to compile flood risk maps in Europe and is included in the European Exchange Circle on Flood Mapping (EXIMAP 2007a) set up to collect all available information and know-how in Europe and improve flood mapping practices in European countries. The flood risk is expressed as a potential loss in a particular area (e.g., ha, km2 ) over a given time period (generally 1 year) and is calculated using the following formula (1.8): Risk = ph × C

(1.8)

where ph probability of danger, C potential adverse consequences (taking into account factors such as exposure and vulnerability, calculated using the following relationship (1.9):

1.1 Assessment of Flood Risk

7

C = V × S(m h ) × E

(1.9)

where V vulnerability: the value of the elements at risk, expressed in money or human life; S susceptibility: the harmful effect of the element at risk (as a function of the size of the hazard such as depth damage, damage time). The range of susceptibility is set from 0 to 1; and E exposure: the likelihood of the presence of elements at risk when the event occurs. The range of exposure is set from 0 to 1. Process approach The process approach is based on descriptions of factors affecting the origin and intensity of processes. Flood risk is defined by the product of three factors: hazard (probability), exposure, and vulnerability, based on the following formula (1.10) (Langhammer 2010): R = H ×E×V

(1.10)

where R H E V

risk, hazard, exposure, and vulnerability.

The process approach was used by Karmakar et al. (2010) using the studies by Kron (2005), Barredo et al. (2007), who expressed flood risk as a threat, vulnerability, and exposure function according to the following formula (1.11):   R = ( pe ) × (V ) × E Land and E Soil

(1.11)

where R pe V E Land E Soil

flood risk, threat expressed as probability of occurrence of potential damage, vulnerability (sensitivity of population to flood damage), exposure expressed in terms of land use, and exposure expressed by soil permeability.

Threats, vulnerabilities, and exposure are interrelated but different from the point of view of their origin, character, and expression. The relationship of these components can be expressed with three sides of a notional triangle, where the individual components are represented by its sides and the resulting risk level is the area of the triangle (Havlík and Salaj 2008) (Fig. 1.2).

8

1 Flood Risk Assessment—State of the Art

Fig. 1.2 Risk components (arranged according to Havlík and Salaj 2008)

The bigger the risk, the greater the threat, the longer the exposure, and the greater ˇ the vulnerability of the object (Camrová and Jilková 2006). To reduce the floodrelated risk, we need to reduce at least one of the sides of this triangle defining the area of risk (Langhammer 2007). However, it is possible to quantify these individual components only after obtaining important information, so it is necessary to define these individual components first. Vulnerability The term vulnerability was first used in the 1970s as an alternative to the probabilitycentric perception of natural hazards, where all damage and negative impacts were related only to the properties of the natural element itself (e.g., extent, intensity, and duration). It indicates how the individual objects in the country (including buildings, ecosystems, and people) are prone to suffer damage and, in part, what the damage will lead to in the longer term (Skubinˇcan 2012). For the needs of flood risk assessment, the concepts of susceptibility, resistance, and resilience (Skubinˇcan 2012) are used for one of the most important definitions of vulnerability. Susceptibility is understood as the predisposition to loss or damage (the potential to suffer damage), which is defined mainly by the internal (physical) attributes of endangered objects. It is a passive component of vulnerability, so increasing susceptibility increases vulnerability. An example of a susceptibility parameter can be, e.g., the number of floors or the material from which houses are built (Skubinˇcan 2012). The terms resilience and resistance are, in contrast, perceived as active components of vulnerability. Their growth diminishes the vulnerability of people, communities, economic, or environmental systems. Both definitions relate to socio-economic characteristics. Resistance is understood to be resistance to the direct consequences of a flood at the time of its action. It speaks of how long the flood-affected system (human,

1.1 Assessment of Flood Risk

9

environmental, and economic) can withstand its negative impact and preserve its functionality without significant changes. Resilience, on the other hand, relates to the potential for restoring human, economic, or environmental systems after the flood, to re-establishment of the pre-flood scenario. However, it should be noted that this is also the ability of the system to adapt during the flood and thus maintain its functionality at this time (Skubinˇcan 2012). In general, we recognize two types of vulnerabilities: vulnerability dependent on hazard (probability of occurrence) and vulnerability independent of hazard (Skubinˇcan 2012). In any attempt to implement vulnerability in research or evaluation, it is important to note that vulnerability cannot be measured. Expressing vulnerability is possible only indirectly, based on the values of certain variable indicators. Two main approaches are used to select vulnerability indicators: deduction, which is largely based on subjective selection of indicators and an inductive approach using statistical analysis of the main components (Skubinˇcan 2012). Thus, vulnerability can be defined as susceptibility to damage. In systems of natural hazards, the element which determines the course of natural threats is the nature of the consequences and the resulting extent of damage (Langhammer 2010). Solin (2011) reported that vulnerability research was developing in two directions. The first direction focuses on analysis of the vulnerability of individuals or groups of people, households, community, nation, and is referred to as “social-based vulnerability” representing the vulnerability of socio-economic structures and linkages (e.g., Penning-Rowsell et al. 2005). The second direction focuses on analysis of the vulnerability of spatial units (grid, polygon, administrative unit, region, and state) and is referred to as “place-based vulnerability,” i.e., the vulnerability of the natural environment (Damm et al. 2010; Meyer et al. 2007). Hazard/Threat In general, a hazard is understood to be a potentially harmful or damaging event, a natural phenomenon or a human activity which may cause loss of life, injury, damage to property, interruption of social or economic networks and activities, and environmental degradation (UN/ISDR 2004). In practice, the term “threat,” which is essentially the equivalent of hazard, is often used (Skubinˇcan 2012). Hazard does not mean damage. Flood hazard analysis is linked to the solution of three main problem areas: estimation of maximum N-year flows, determination of the water level for individual N-year maximum flows, and subsequently the definition of potentially flooded areas (Skubinˇcan 2012). In Directive 2007/60/EC, Chap. III, Article 6 states that “flood hazard maps provide information on flood attributes that are injurious to humans during the flood, with low, medium or high probability of repetition. Flood hazard maps are based on a combination of flood scale, water depth, or water level, water flow rate, or appropriate water flow, if applicable.” The main objective is to obtain the range of potentially flooded (threatened) territory, which is the basis for further flood risk analysis. In the definitions of multidimensional risk (Sect. 1.1.1), the term “hazard” is used in a context that corresponds to a probable definition of flood risk.

10

1 Flood Risk Assessment—State of the Art

However, as stated by Solín and Martinˇcáková (2007), the term hazard is also used in other meanings that do not include probability quantification. For example, Smith (1996) states that hazard poses a potential threat to humans and their well-being. Langhammer (2010) states that the threat component represents a natural stochastic process which causes a threat to the natural or social system. Flood risk is a causal process which causes floods, including atmospheric precipitation, snow melt, or processes causing the breach of a dyke. In general, areas with poorly permeable soils, with a high proportion of urbanized, technical, and arable land, are more likely to be flooded than areas with permeable soils and a high proportion of forest and grassland (Solín and Martinˇcáková 2007). Exposure The exposure component represents the potential for damage because it relates to property in any area threatened by a natural process. Exposure also includes the time during which the landscape and objects in it are exposed to an unfavorable phenomenon, e.g., flooding. In this case, these objects are, for example, residential and commercial buildings, industrial sites, infrastructure, and movable property which are threatened by floods (Langhammer 2010; Dráb 2006). During the twentieth century, the value of tangible and intangible assets threatened by natural processes constantly rose in all economically advanced countries. The rise in value was mainly due to the economic growth of each country, due to the differing political and economic development of individual states and the socio-economic specificities of particular regions, whereby the resulting economic levels and their dynamics were markedly variable in time and space (Langhammer 2010).

1.2 Risk Analysis of Floodplains Risk assessment and risk analysis methods are gaining more and more attention in the areas of flood protection and flood risk, as they allow us to assess the costeffectiveness of mitigation measures and thereby optimize investment (Ganoulis 2003; Hardmeyer and Spencer 2007; Apel et al. 2009). The main objective of risk analysis (RA) of floodplains is to estimate the need for protective measures. Flood risk analysis can also depend on the relationship of risk objects to adverse events, i.e., flooding. Figure 1.3 shows a general risk model. Risk analysis methods and procedures are well developed throughout the world. Moreover, many projects address flood risk assessment and flood damage assessments to protect people and their property living on floodplains. This topic is develˇ oped in a monograph (Ríha et al. 2005) and in several book publications (Dráb 2006; ˇ Drbal et al. 2005; Drbal et al. 2008; Satrapa et al. 2011; Dráb and Ríha 2001). In order to assess the extent of flood risk, flood protection, and corresponding flood protection measures, various risk analysis methods and tools are currently used, as described in the following section.

1.2 Risk Analysis of Floodplains

11

Fig. 1.3 Model of flood risk development adjusted by (arranged according to Kandráˇc 2011)

1.2.1 Risk Analysis Methods and Approaches The development of risk analysis methods is closely related to the classification of the territory according to its vulnerability, using mathematical modeling of rainfall and runoff processes and the flow of water in the rivers and inundations, and the assessment of damage (Cipovová 2010). From the conceptual point of view, risk analysis includes qualitative, quantitative, and semi-quantitative approaches.

12

1 Flood Risk Assessment—State of the Art

1.2.1.1

Qualitative Approach to Flood Risk Assessment

A qualitative approach has the aim of identifying possible sequences of events, threatening scenarios that figuratively portray the potential situation resulting in damage. Each scenario needs to be specially assessed and analyzed. Based on the results of this analysis, the types of hazards are identified and, at the same time, the elements of the system requiring more attention. A very important role here is played by the compilation of checklists, the design of system element diagrams, and analysis based on the types of disturbances and consequences (Drbal et al. 2008).

1.2.1.2

A Quantitative Approach to Flood Risk Assessment

The quantitative approach involves determining the probability of the end-to-end status of the entire system, thereby expressing its reliability based on the probability of occurrence of individual threatening scenarios. At the same time, the quantified impacts of the flood are determined (e.g., in financial units, or the number of deaths and injuries). The resulting risk is calculated as a function of the probability and impact. In quantification of partial risk, the probability of damage is used as a quantifier in a single underlying scenario. Determining the partial risks in terms of probability and consequences for the quantification of damage involves the most demanding work in risk engineering. Direct and indirect damage, tangible and intangible damage, social and economic analyses, as well as analyses of impacts on the environment, the landscape and extensive use of inland areas may all be assessed (Drbal et al. 2008). Quantitative risk assessment methods belong in a group of approaches based on the expression of potential damage. Quantitative analysis consists of evaluating the potential flood threat, the vulnerability of the territory, assessing the direct and induced economic and non-economic impacts (damages). For each threat scenario, a probability estimate is made. The final step is the definition and quantification of risk. In determining the type of flood damage, as far as possible all important items such as direct damage (death and injury, damage to buildings and technical equipment, but also damage to agriculture and environmental damage) and indirect damage including the consequences of direct damage (e.g., fire, contamination due to pollution, damage due to soil movements). When determining the type of damage including flood damage on individual areas, it is necessary to take into account, as far as possible, all the essential items (Dráb ˇ and Ríha 2001): • Determining the extent of direct damage, in particular: – injuries and deaths among the population, – disturbance of structures of buildings, – damage to technical equipment (machinery and equipment), and

1.2 Risk Analysis of Floodplains

13

• damage to nature (or environmental damage). • Determination of indirect damage resulting from direct damage (e.g., fires, contamination by dangerous substances). • Direct damage is expressed in terms of costs of damage to buildings, costs of population evacuation and treatment, or replacement transportation. Their estimation is possible based on knowledge of direct damage with possible use of damage functions. • The calculation of indirect damage (e.g., unemployment, company failures) is very challenging and requires good knowledge of the region, including modes of population migration. A significant advantage of this process using methods of calculating potential losses is the acquisition of detailed qualitative and quantitative information on the possible course of the flood and on the probability of each causal event, such as the flood occurrence, deterioration of levees, or flood damage and costs. The results of the solution allow the definition of the most endangered elements of the system or, respectively, the elements posing the greatest risk to the system. In general, most methods for determining potential flood damage used in the world are based on the same principle of applying some kind of loss curve method. These methods express directly the magnitude of damage to the financial cost, depending on the hydraulic parameters of the flood (depth, velocity, and duration) (Nascimento et al. 2006; Meyer and Messner 2005), or the damage amount expressed by relating the damage to property to its size (Horský 2008; Satrapa 1999; Korytarova et al. 2007), or the percentage of damage from the maximum possible damage to the property (Kok et al. 2004). Methods based on the expression of potential losses are the most demanding of all the methods available, but they allow damage in the floodplain and hence the ˇ economic benefit of flood control measures to be assessed (Ríha et al. 2005).

1.2.1.3

Semi-Quantitative Approach to Flood Risk Assessment

The semi-quantitative approach represents an intermediate stage between qualitative analysis which does not give a calculation of the extent of flood risk and quantitative analysis which requires relatively extensive and credible data together with the use of special techniques. The result of semi-quantitative evaluation is the relative height of the risk expressed with a numerical or color scale. The risk is not expressed in monetary units or losses in human lives as in quantitative methods, but as a dimensionless quantity in the units of the respective variables characterizing the threat or the impact of floods (Drbal et al. 2008). The most significant semi-quantitative methods include the maximum acceptable risk method, the risk matrix method, or failure modes effects and criticality analysis (FMECA) method.

14

1 Flood Risk Assessment—State of the Art

Risk matrix method Risk matrix-based methods are one of the simplest procedures for the preliminary assessment of potential flood risks. In this method, the risk is considered as a function of the probability of exceeding a specified flood (flood intensity), where flood intensity means the rate of flood destruction, i.e., the function of water depth and ˇ flow velocity (Dráb 2006; Ríha et al. 2008). The method consists of two basic steps (Dráb 2006): (a) quantification of flood hazard—calculation of flood intensity and (b) flood risk assessment using a risk matrix. (a) Flood hazard quantification—Flood intensity calculation As part of this step, it is necessary to define and describe the hazard expressed in terms of the intensity of the flood. This is understood as a flood destruction measure and is defined as a function of the water depth in [m] and the water flow velocity in [m/s] (Dráb 2006). Calculated flood intensity values can be classified into several categories (large, medium, and low) based on a survey of potential damage to population health and property in floodplain areas. Based on the detected intensity of the flood, the hazard category is determined, i.e., what level of damage to humans, animals, and buildings is to be expected at a certain intensity. (b) Determination of flood risk by means of a risk matrix The practical procedure for determining the threat is similar to the calculation of flood intensity. Input is information containing the flood intensity information for a given return period of N-year flow. The risk matrix is shown in Fig. 1.4. As a result of this method, in the first step of the threat map (Fig. 1.4), the categories of vulnerable areas in the flood plain area are displayed using a color scale. Based on this, the hazard is expressed as 1 to 4 (low, medium, high, and very high) (Dráb 2006). The next step is to evaluate risk index (RI) maximum values for individual RIi of sub-hazards corresponding to i-hazard scenarios. Based on the resulting RI, the hazard category (high, medium, low, and residual) is determined (Dráb 2006). In the last step of the risk-based method, a risk map is produced which is the result of a combination of hazard data and information on the vulnerability of objects in the exposed area (Drbal et al. 2008; Cihláˇr et al. 2010). Methods based on the expression of maximum acceptable risk Methods based on the expression of the maximum acceptable risk do not actually measure the acceptable risk level but the acceptable magnitude of the characteristics of the course of the flood (depth of water, water velocity). The advantage of this kind of method is that it does not require more detailed input data from the field of damage assessment and it is appropriate for the input of basic hydrological and hydraulic data and the unsophisticated technical and software equipment of the assessor (Cipovová ˇ 2010; Ríha et al. 2005). The assessment of the vulnerability of the area precedes its categorization. The vulnerability of the territory then expresses the value of the maximum acceptable

1.2 Risk Analysis of Floodplains

15

Fig. 1.4 Risk matrix along with the procedure for drawing up the hazard map (arranged according to Dráb 2006)

ˇ Table 1.2 Examples of maximum acceptable risk values (Ríha et al. 2005) Territory category

Maximum acceptable risk

Urbanized territory First floor (water height is 2.5 m above terrain), return period of N-year flood wave—1000 years Ground floor (water height is 0.5 m above terrain), return period of N-year flood wave—100 years Ground (water height is 0.5 m under the terrain), return period of N-year flood wave—10 years

risk for each category of territory. A sample of the maximum acceptable risk values ˇ for selected territory categories is shown in Table 1.2 (Ríha et al. 2005; Kudrnová et al. 2004). Risk maps are then generated as a combination or overlap of mapping characteristics of the flood with the vulnerability maps. The advantages of this method are the usual requirements for input data, equipment requirements, and the qualification of ˇ the workplace of the assessor (Ríha et al. 2005; Kudrnová et al. 2004).

1.2.2 Risk Analysis Tools At present, the level of use of mathematical models and geographic information systems in flood management has turned them into very common tools for data evaluation and interpretation. The purpose of deploying these tools is, in particular,

16

1 Flood Risk Assessment—State of the Art

to speed up the process of flood risk analysis and minimize the need for local scrutiny, flood damage, and risk maps.

1.2.2.1

Mathematical Modeling and Software Resources

Mathematical modeling is an effective method of understanding the properties of the subject under investigation. The application of fully dynamic mathematical models enables us to get the most comprehensive knowledge about water bodies. A mathematical model represents the idealization of a real physical system (Kutiš 2006; Hˇrebíˇcek et al. 2010). The combination of the choice of equation systems and methods used for their numerical solution affects the properties of the mathematical model and the predicted utility of modeling results, especially with regard to spatial schematization. According to the spatial schematics approach, the models can be divided into one dimensional (1D), quasi-two dimensional (1.5D), two dimensional (2D), and three dimensional (3D). (a) The uni-dimensional model (1D) (Fig. 1.5) shows the maximum idealization of an actual three-dimensional problem into a one-dimensional system. If it is a problem of boundary values (the aim is to identify an unknown quantity, e.g., the temperature of the system at a particular time), the result is an ordinary differential equation. The largest application of 1D models in water management practice is to calculate steady and unsteady flow in open channels and water streams, in areas where the flow is of mostly one-dimensional character (flow in a riverbed or a river with an adjacent inundation area of smaller size and regular shape) (Kutiš 2006; Valenta 2005).

Fig. 1.5 Channel and flooding scheme using cross sections, 1D model output (arranged according to Valenta 2005)

1.2 Risk Analysis of Floodplains

17

(b) The two-dimensional model (2D) (Fig. 1.6) is more complex compared to the 1D model, and the result is a partial differential equation. The use of 2D models in water management is typically the modeling of the flow in complex spatial conditions (irregular shape of the adjacent floodplain area or when there are obstacles in the water flow, e.g., built areas) (Kutiš 2006; Valenta 2005). (c) The three-dimensional model (3D) (Fig. 1.7) is the most comprehensive and the most complicated, and its use may not always be the most effective as the result is also a partial differential equation. Use of these models for describing water flow is prevented by the extraordinary demands of 3D models on the hardware used (Kutiš 2006; Valenta 2005).

Fig. 1.6 Demonstration of results of 2D flood model of Modra Town (left), demonstration of work output of 2D model of the Váh River—depth of water with flow vectors (right) (arranged according to Mišík et al. 2011a, b)

Fig. 1.7 Three-dimensional representation of a flood in Bratislava—Mlynské nivy (arranged according to Mišík et al. 2011b)

18

1 Flood Risk Assessment—State of the Art

The classic approach to mathematical modeling of flood situations is the application of different types of one-dimensional models allowing the determination of the longitudinal profile of water levels along the axis of a stream at peak flood flows. Current evolution in the field of mathematical modeling of flood situations is focused on the development and application of multidimensional numerical models, especially two-dimensional models. This is due to the fact that the output of these models contains much more data, in addition to the basic information about water levels, for example, information on the overall character of the stream current, the way it flows around obstacles, and information on water depths, directions of flow and velocities in the whole range of the model area, which is also data of extraordinary importance for the analysis of flood situations and subsequent qualified planning and decision-making (Valenta 2005). The results of mathematical models and other hydro-informatics tools are helpful in all phases of flood risk management, especially in defining floodplains and creating flood maps. Mapping the flooding of a floodplain requires full dynamic simulation of the flood wave progress. These requirements are met by MIKE 11, MIKE 21, or MIKE FLOOD simulation software (depending on the character of the study area), followed by mapping of the flooded area and the required hydraulic quantities in defined time steps. The representation of flood animation is possible with MIKE GIS, MIKE View Flood Mapping or Result Viewer or MIKE Animator (Baˇcík et al. 2005; Fencík et al. 2011).

1.2.2.2

Geographic Information Systems

Geographic information systems (GIS) can be used for preparing the basis as well as for compiling the resulting flood map, so they belong among the necessary tools for carrying out flood risk analysis. It is quite difficult to clearly define geographic information systems (GIS) because there are several different approaches (Drobne and Lisec 2009). The main cause of the difficulties in defining GIS is related to determining the main focus of interest in their activities. Most GIS definitions focus on two aspects: technologies and/or problem-solving. As a general rule, the definition used by the Environmental Systems Research Institute (ESRI) in materials accompanying its PC ARC/INFO system is “GIS is an organized set of computer hardware, software and geographic data (a packed data base) designed for efficiently retrieving, saving, modifying, managing, analyzing and displaying all forms of geographic information”. Although the definitions of GIS differ to a certain extent, all agree on one point: GIS are considered as computer systems that work with geographic information. In GIS, reality is represented by objects that have two types of data defined (ESRI): • geographic (geometric, also called localization) data relating to any information about location and • attributable (statistical or non-localizing) data relating to position only on a world scale and in the real world.

1.2 Risk Analysis of Floodplains

19

One of the main differences between GIS and other software working with geographic (graphic) information (e.g., CAD, CAM) is that GIS allow for spatial analysis and modeling (Hofierka 2003). Geographic objects can be represented by means of the following data models (Tuˇcek 1998): • Raster model—regular distributed points or spatial elements (pixels) containing a zero or non-zero value. The basic building unit is the cell. • Vector model—geographic objects are represented by points, lines, and polygons defined by their geographical coordinates, where • points are the basic elements of the vector representation of the data with positions uniquely determined by coordinates [x, y] in the respective plan/map coordinate system, • lines are formed by sets of points, and • polygons are flat objects defined by closed lines. • Point model—a special category of the vector model. These are points regularly or irregularly distributed and represented by cartographic coordinates. Each point can carry “n” attributes. • Attributes—descriptive data providing information about geometric data. Attribute data are typically stored in an external or internal database system (DBMS). According to the data structure in which the information is disseminated, geographic information can be divided into the following types (Tuˇcek 1998): • Graphic—holding information in graphical form, examples of this type are various raster images (e.g., .tiff, .bmp, and .jpeg). • Database—information is stored in a structured database (for example, ESRI Shape format). • Text—the simplest type where information is stored in the form of a text file. • Spreadsheet—information is stored in spreadsheet form (e.g., .xls format of the MS Excel spreadsheet). The use of GIS is varied, and they are now used wherever it is necessary to work with information related to Earth’s surface, so they have become an irreplaceable aid in flood management. Another form of support, or a so-called tool for flood risk analysis, especially in the decision-making process, is called multi-criteria decision-making, otherwise known as multi-criteria analysis.

1.2.2.3

Multi-Criteria Analysis

Multi-criteria analysis is a method of quantitative evaluation resulting in an overall assessment of the status and comparison of several variants (Meyer et al. 2007). As a rule, several components enter the multi-criteria analysis (Fig. 1.8).

20

1 Flood Risk Assessment—State of the Art

Fig. 1.8 Relations in multi-criteria analysis and decision matrix (arranged according to Skubinˇcan 2010)

Firstly, there is a defined goal or what needs to be done using the analysis. The evaluation criteria for each of the alternatives (solutions) are defined by the evaluator, covering the partial objectives as well as those described by the attributes. Evaluator preferences are further specified by assigning weights to individual criteria. The choice of an alternative is made on the basis of decision rules, which can be understood as a procedure involving the ranking of the different alternatives from the worst to the best. The conclusion is the output in the form of a recommendation of a specific alternative (Skubinˇcan 2010). Based on the nature and the way of using the information by the evaluator, it is possible to divide the methods of multi-criteria analysis into the following groups: axiomatic methods, direct methods, methods of compromise, methods of comparability thresholds, human–computer dialog methods (Ocelníková 2004). There is a large number of methods of multi-criteria analysis from the simplest, e.g., the decision matrix (DMM) method or the pairwise comparison method (FDMM), to the more laborious but more objective Analytical Hierarchy Method (AHP), which, however, for its use requires computing techniques with specific software. The common feature of all these methods is that they assess multiple variants of a possible solution according to the various criteria set. In the first instance, the weighting of the individual criteria (assessment of their importance in terms of the intended purpose) is determined first, and then the evaluator quantitatively assesses how the individual solution variants meet the chosen criteria (Máca and Leitner 2002). The various methods differ in their particular ways of quantification in the evaluations (Máca and Leitner 2006).

1.2 Risk Analysis of Floodplains

21

The fact that multi-criteria analysis methods are currently being used in the area of flood risk assessment is also demonstrated in a number of research works (Tran et al. 2009; Yalcin and Akyurek 2004; Chadran and Joisy, 2009; Tanavud et al. 2004; Scheuer et al. 2011; Kandilioti and Makropoulos 2012; Yahaya et al. 2010), in which multi-criteria analysis is most often applied in the environment of geographic information systems.

1.3 Laws on Flood Risk Management European states have accepted, especially after a series of floods with severe consequences, various national programs to increase the level of flood protection, which are also usually aimed at reconciling differing aims among neighbors in specific catchment areas. Priorities arising from the urgency of flood protection and the level of cooperation between states vary across Europe. The intensity of governments’ interest in floods is affected by the implementation of systematic measures outlined in the adopted programs, and tends to decline depending on the time elapsed since the last major floods (Baˇcík et al. 2006). As the nature of the floods and levels of flood risk differ across Europe, each government’s approach to flood management also differs. Following the floods in the summer of 2002, several EU Member States directed the Council of the European Union’s attention to flood prevention and protection. In response to these floods, the European Commission published a document (draft directive) on flood risk management, prevention, protection, and mitigation (COM 2004) in July 2004. In this document, the Commission analyzed the current situation in detail and concluded that concerted and coordinated action at EU level could have been a significant contribution and would increase the overall level of flood protection. In the first phase, the Commission’s work on the preparation of the European Foresight Action Program for External Studies of Floods was preceded by the European Union’s consultations in June 2005 (International Office for Water 2005), and the delivery of information and background material to the European Commission from the Member States and Candidate Countries associated in the European Free Trade Area (EFTA). The Representatives of the Member States of the Union, at their working meetings on January 21, April 11, and September 16, 2005, further developed the work on the preparation of a flood risk management document fully respecting the Water Framework Directive 2000/60/EC and further extending its area of application. Based on the results of these meetings, the preparatory work was completed with public Internet consultation, which ran intensively from July 20 to September 14, 2005. The Commission was then able to identify and confirm the formulation of the basic objective of the legislative standard and to achieve general consensus on the main content points (Baˇcík et al. 2006). On October 23, 2007, this initiative led the European Parliament and the Council to adopt Directive 2007/60/EC on the assessment and management of flood risks and, pursuant to Article 17 Sect. 1.1, the Member States of the European Union were

22

1 Flood Risk Assessment—State of the Art

Fig. 1.9 Flood risk management objectives (arranged according to Directive 2007/60/EC)

required to bring into force, by November 26, 2009 at the latest, all laws, regulations, and measures necessary to comply with the Directive. Directive 2007/60/EC of the European Parliament and of the Council on the assessment and management of flood risks together with generally binding regulations set out a comprehensive flood risk management planning system (Fig. 1.9), namely, 1. All Member States of the European Union (EU) are to carry out, by December 22, 2011 at the latest, a preliminary flood risk assessment in order to identify areas where there are potentially significant flood risks, or where floods can be expected to occur. The preliminary flood risk assessment shall be reassessed and updated as necessary by December 22, 2017 and every 6 years thereafter. 2. For areas where significant flood risks have been identified with a presumption of their probable occurrence, the Members are to prepare, no later than December 22, 2013: a. flood hazard maps, b. flood risk maps. Flood hazard maps and flood risk maps are to be reviewed and updated if necessary by December 22, 2019 and then every 6 years. 3. For areas where existing or potential flood risks have been identified, based on the results of their preliminary flood risk assessments and flood hazard and flood risk maps, the Member States are to set appropriate flood risk management objectives and, by December 22, 2015 at the latest, draw up flood risk management plans. The flood risk management plans are to be reviewed and updated if necessary by December 22, 2021 and then every 6 years. Directive 2007/60/EC applies to inland waters as well as to all coastal waters throughout the European Union. All estimates, maps, and prepared plans must be

1.3 Laws on Flood Risk Management

23

available to the public. Member States also need to coordinate their flood risk management practices in shared river basins, including third countries, and undertake not to take measures that would increase flood risk in neighboring countries. Member States must take into account long-term developments, including climate change, as well as sustainable land use (Alphen et al. 2009; Baˇcík et al. 2009). Directive 2007/60/EC on the assessment and management of flood risks: • provides for flexibility in transposition and implementation, binding in all EU states as a whole, in international as well as exclusively national river basins; • implementation means defining levels of flood protection, the necessary measures and deadlines for their implementation, whereby details are the responsibility of individual Member States; and • creates the necessary regulatory framework for the establishment of coordination and planning systems at the level of the entire natural catchment area, leaving decisions on key details (level of protection, types of measures, and dates for implementation) to the discretion of the Member States, also with regard to their shared river basins. Directive 2007/60/EC of the European Parliament and of the Council of August 23, 2007 on the assessment and management of flood risks was transposed into the legal system of the Slovak Republic by Law No. 7/2010 Coll. on the protection against floods, which the National Council of the Slovak Republic passed on December 2, 2009, became effective on December 1, 2010 and was published on January 12, 2010 in the Collection of Laws as No. 7/2010. Law No. 7/2010 Coll. on flood protection (of the Slovak Republic) provides • flood protection measures and obligations to assess and manage flood risks in order to reduce the adverse impacts of floods on human health, the environment, cultural heritage, and economic activity; • planning, organization, and management of flood protection; • obligations and rights of state administration bodies, flood protection authorities, higher territorial units, and municipalities; • obligations and rights of legal entities and entrepreneurs in flood protection; and • responsibility for breaching the obligations imposed by this law. Law No. 7/2010 Coll. is complemented by the following decrees issued by the Ministry of the Environment of the Slovak Republic (MoE SR): • Decree of the MoE SR No. 251/2010 Coll., setting out the details of the evaluation of the costs of flood protection work, flood rescue work, and flood damage. • Decree of the MoE SR No. 252/2010 Coll., laying down detailed rules for the submission of interim reports on flood situations and summary reports on the course of the floods, their consequences, and the subsequent measures taken. • Decree of the MoE SR No. 261/2010 Coll., setting out the details on the content of flood plans and the procedure for their approval. • Decree of the MoE SR No. 204/2010 Coll., setting out the details of the implementation of the prescribed flood service.

24

1 Flood Risk Assessment—State of the Art

• Decree of the MoE SR No. 313/2010 Coll., setting out the details of the preliminary flood risk assessment and its review and updating. • Decree of the MoE SR No. 419/2010 Coll., setting out the details of the preparation of flood hazard maps and flood risk maps, the reimbursement of expenses for their preparation, reassessment and updating, and the design and display of the extent of floodplain areas on the maps. • Decree of the MoE SR No. 112/2011 Coll., setting out the details of the content, re-evaluation, and updating of the flood risk management plans. The management of flood risks in the Slovak Republic is not only the subject of Law No. 7/2010 Coll. on flood protection, but further relies on a number of laws regulating the activities of state and local government and authorities within their establishing jurisdiction, and the responsibilities of legal entities and natural persons directly or indirectly related to the complex of activities constituting the flood protection system in Annex 1 to the document “Analysis of the state of flood protection in the territory of the Slovak Republic” (MoE 2011e).

1.3.1 Flood Protection Programs in the EU and Slovakia Individual EU countries over the past years have added legislation on flood protection (vid the abovementioned law on flood protection in the Slovak Republic), drawn up action plans for flood protection, and introduced methodologies for the implementation of Directive 2007/60/EC in the field of flood hazard mapping and risk assessments for each country as a whole, as well as for individual river basins. The report by Szolgay (2010) shows the following flood protection programs in the EU and Slovakia. In Germany, a series of documents were issued by the Working Party of the Republic and Federal States of the FRG for Water (LAWA 1996, 2000, 2010). The International Commission for the Protection of the Rhine and Danube processed action plans for the basins of these rivers (IKSR 2005; ICPDR 2004), and for the river basins in Slovakia there are specific action plans including measures in the field of landscape and urban planning (ICPDR 2009). NGOs, such as the World Wildlife Fund and Global Water Partnership, and international organizations such as the United States, World Meteorological Organization (WMO) have prepared their own plans. Virtually all these materials contain similar recommendations and requirements for landscape development and protection. The proposed solutions sometimes repeat them, or otherwise take over and slightly adjust them. Many refer to (COM 2003), including the Country Revival Program and Integrated River Basin Management of the Slovak Republic, approved by the Government of the SR in October 2010.

1.3 Laws on Flood Risk Management

25

1.3.2 Preliminary Flood Risk Assessment As mentioned above, the Preliminary Flood Risk Assessment (PFRA) is the first objective of Directive 2007/60/EC. PFRA is conducted to provide a risk assessment and is based on information that is available or can easily be obtained. The evaluation includes (Directive 2007/60/EC, SR Law No. 7/2010 Coll.) • “maps of the river basins at an appropriate scale, showing the boundaries of catchment areas, sub-basins and coastal areas, if any, with topography and land use”; • “a description of the floods that have occurred in the past and have had significant adverse impacts on human health, the environment, cultural heritage and economic activity, and which are still likely to occur in the future, including their extent and course of action and the assessment of adverse impacts which they caused”; and • “a description of the significant floods that have occurred in the past, as long as the adverse consequences of such events in the future can be expected.” Sec. 8 and Sec. 50 subsec. 2 a) of Law No. 7/2010 Coll. of 22 June 2010, and the Decree of the Ministry of the Environment of the Slovak Republic No. 313/2010 Coll., setting out the details of the preliminary flood risk assessment and its revaluation and updating (Collection of Laws, No. 119/2010, page 2578, 8 July 2010), together stipulate what the preliminary flood risk assessment should contain. The PFRA is a general description of the geographic definition of the assessed area together with mapping of the river basin area and the sub-basins at a suitable scale, description of the natural conditions and geomorphological characteristics of each sub-basin, identification of the sections of watercourses pursuant to Sec. 2 subsec. 1 and Sec. 3, and significant surface runoff routes that may cause flooding of the area, a description of significant floods in the past and flood protection infrastructure in each sub-basin. The work to establish the framework and progress steps in the preparation of the preliminary flood risk assessment was initiated in the Slovak Republic on December 1, 2010, aiming to identify in the territory of the Slovak Republic areas with potentially significant flood risk and areas with a likely occurrence of potentially significant flood risk. The preliminary flood risk assessment was carried out throughout the territory of the Slovak Republic in all 10 sub-basins making up the administrative territories of the Danube and Vistula Basins. The preparation of the preliminary flood risk assessment was undertaken by the Ministry of the Environment of the Slovak Republic through the Slovak Water Management Company, Banska Stiavnica, and completed on December 22, 2011. The preliminary flood risk assessment was based on available information on the causes, courses, and consequences of the floods that occurred in Slovakia during the 14-year period from the beginning of 1997 to the end of 2010. The assessment of the potential significant flood risks included 2488 geographic areas from the whole territory of Slovakia (municipalities and sections of watercourses), for which during the evaluated period the third level of flood activity was declared at least once (MoE 2012a, b, c, d).

26

1 Flood Risk Assessment—State of the Art

Directive 2007/60/EC requires EU Member States to coordinate the identification of geographic areas with existing potentially significant flood risks and their presumed likely occurrences appertaining to international river basins (MoE 2012a, b, c, d).

1.3.3 Flood Hazard Maps and Flood Risk Maps The second objective of Directive 2007/60/EC is to have flood hazard maps (Fig. 1.10) and flood risk maps (Fig. 1.11) drawn up on the basis of preliminary flood risk assessments for those areas in which there are potentially significant flood risks, or it may be presumed that their occurrence is likely. These maps have to be drawn up at the most appropriate scale. The flood hazard map shows the possible extent of flooding in the area covered (Directive 2007/60/EC, SR Law No. 7/2010 Coll.), indicating the following: • Flood with a low probability of occurrence, which is – flood which may be repeated once every 1,000 years or less; – flood with exceptionally dangerous course; • Flood with a medium probability of occurrence, which may be repeated once every 100 years; and • Flood with a high probability of occurrence, which can be repeated once every 50, 10, and 5 years. The flood hazard map shows the flood extent defined by the flood line, depth of water or water level, and the flow rate of water or the corresponding flow.

Fig. 1.10 Map of the flood hazard in the Hornád River Basin (arranged according to MoE SR 2013)

1.3 Laws on Flood Risk Management

27

Fig. 1.11 Map of the flood risk in the Hornád River Basin (arranged according to MoE SR 2013)

The flood risk map contains data on potentially adverse impacts of floods as displayed on flood hazard maps. The flood risk map contains the following data (Directive 2007/60/EC, SR Law No. 7/2010 Coll.): • Flood line that limits floods to a potentially endangered area consistent with the flood line displayed on the flood hazard map. • Data of the estimated number of population potentially endangered by floods. • Types of economic activities in areas potentially endangered by floods. • Sites with industrial activities which can cause water pollution during flooding. • Location of potentially endangered areas concerning water for human consumption and recreational activities. • Locations with water suitable for swimming. • Information on other significant sources of potential water pollution after flooding. • Areas making up the national system of protected areas and the European system of proposed and declared protected areas (NATURA 2000), if they are located in the geographical area displayed on the flood hazard map. • Information which the Ministry considers useful on the flood risk maps and which has been transmitted by the water management executive in charge of the significant waterways at least 1 year before the completion or re-evaluation and updating of the flood risk maps. Flood maps are an indispensable tool in these phases of risk management (Baˇcík et al. 2005): • In the prevention and protection phases, the assessment of flood risk and then the design of measures and the assessment of their general protective effectiveness and the detailed technical and economic assessment of the effectiveness of the proposed measures on the basis of a cost/benefit ratio.

28

1 Flood Risk Assessment—State of the Art

• At the stage of preparedness, where protection plans are primarily geared to ensuring areas where the greatest flood threat is suspected. • In the hazard response stage, which must correspond to the speed and the flooding process. In rescue plans, it is necessary to prioritize reliable evacuation routes and to ensure that substitute accommodation for the affected population, substitute placements for displaced animals, and material and areas of concentrating the rescue equipment are located in safe places. Flood maps enable (Konviˇcka et al. 2002) the following: • Municipal governments to undertake better planning of new constructions. • Water management organizations to better identify the flood risk places where it is necessary to implement flood protection measures. • Inhabitants of municipalities to know the degree of flood hazard to their property. • Insurance companies to estimate the risks of insurance contracts, and ideally to install alarm systems in the most flood vulnerable areas. Maps are being prepared and updated in digital and analog forms with technical specifications established by the water management executive in charge of the watercourses. They display the same geographic areas at the same scale and on the same number of map sheets where there is a potentially significant flood risk or where it is likely to occur (Fencík et al. 2011; Directive 2007/60/EC). The methodological framework for the creation of flood maps is outlined in MoE SR Decree No. 419/2010 Coll., setting out the details of the preparation of flood hazard maps and flood risk maps, reimbursement of expenses for their preparation, revaluation and updating, and the design and display of the extent of floodplain land on maps. In the Slovak Republic, the organization responsible for the preparation of flood hazard maps and flood risk maps, and for the water management of river basins is the Slovak Water Management Company, Banska Stiavnica. Flood hazard maps and flood risk maps for the whole of Slovakia as well as for individual sub-basins are currently being published and made available on the website of the Ministry of Environment of the Slovak Republic in the section on flood protection (http://www.minzp.sk/sekcie/temy-oblasti/water/protection-beforeoriginal/Management-flood-riskmanagement/flood-mapy.html).

1.3.4 Flood Risk Management Plans The third and last objective of Directive 2007/60/EC and SR Law No. 7/2010 Coll. is based on flood hazard maps and flood risk maps for sub-basins to develop flood risk management plans. These plans are intended to set appropriate flood risk management objectives for sub-basin geographical areas located in the river basin area where there is a potentially significant flood risk or where it is probable that floods will occur. The objectives of the flood risk management plans are to reduce the probability of

1.3 Laws on Flood Risk Management

29

floods and to reduce the potential adverse consequences of flooding on human health, the environment, cultural heritage, and economic activity. Management plans include measures to achieve the primary management objective, which is to reduce flood risk to an acceptable level. The plans must take into account the costs and benefits of the proposed measures. The flood risk management plan addresses all aspects of flood risk management, focusing on prevention, protection, preparedness, including flood forecasting and early warning systems, taking into account the natural characteristics of individual river basins or sub-basins. Management plans are part of the design of long-term river basin management (Directive 2007/60/EC), (SR Law No. 7/2010 Coll.). Drafting of the first flood risk management plans, reassessing them, and updating them are ensured by the Ministry through the designated person and the manager of the significant watercourses in cooperation with flood protection authorities, land planning authorities, other relevant state administration authorities, small watercourse managers and owners, agricultural landowners, and forestry landowners. The municipalities are also involved in the preparation, re-evaluation, and updation of flood risk management plans with the water management company and the authorized persons (Directive 2007/60/EC), (SR Law No. 7/2010 Coll.). Flood risk management plans should be developed on the basis of the following general principles (COM 2004): • Cross-border rivers: Member States should agree to cooperate on the development and implementation of flood risk management plans. In the case of river basins with non-EU Member States, existing coordination mechanisms will be used or new ones will be developed. • Flood risk management plans: for rivers, full integration with river basin management plans and action programs developed in line with the WFD. • Long-term strategic approach: it is necessary to include expected developments in the long-term horizon (50–100 years). • Interdisciplinary approach: all relevant aspects of water management, planning, land use, agriculture, transport and urbanization, and nature protection at all levels (national, regional, and local) must be taken into account. • The principle of solidarity: flood protection measures should not weaken the ability of other regions or Member States occupying the upper or lower sections of watercourses to achieve the level of flood protection which the regions or Member States consider as appropriate. An adequate strategy consists of an approach that includes three steps: retention, preservation, and release of water. • It is necessary to cover all elements of flood risk management. Flood management plans should lead to these global objectives (COM 2004): • Reducing the adverse impacts of floods and the likelihood of flooding. • Promoting sustainable risk management measures for flood risks. • Looking for opportunities to work with natural processes and to enjoy (if possible) the various benefits of flood risk management.

30

1 Flood Risk Assessment—State of the Art

• Informing the public and relevant authorities about the risk of floods and the way they are managed. Key outputs from flood risk management plans should be (COM 2004) • Overview and understanding of the size, nature, and distribution of current flood risks and scenarios of future flood risks. • Understanding flood processes and their susceptibility to change. • A list of cost-effective flood risk management measures to be implemented. • Flood risk maps. • Long-term flood risk management strategies that meet the objectives of the river basin. • If necessary, a set of other activities/studies for the river basins with priority of concern. In the Slovak Republic, ten flood risk management plans were drawn up as at December 22, 2015 for all sub-basins in the Slovak Republic, while (MoE 2011e) • The flood risk management plan of the Morava sub-basin was prepared in cooperation with Austria under the coordination of the Czech Republic. • The Danube flood risk management plan was coordinated with the preparation of a flood risk management plan for the central part of the Pannonian Danube intermediate line from the mouth of the Morava to the Drava and will become part of it, with Slovakia working with Croatia, Hungary, and Austria to draft the plan. • Three flood risk management plans for the Vah, Hron, and Ipel sub-basins were combined into one joint international plan developed by Slovakia in cooperation with Hungary. • Four flood risk management plans for the Bodrog, Bodva, Hornad, and Slana subbasins have become part of the international Tisza flood risk management plan jointly developed by Hungary, Romania, Slovakia, Serbia, and Ukraine. • The flood risk management plan for the Dunajec and Poprad sub-basins was drawn up in cooperation with Poland and became part of the international flood risk management plan for the Vistula. The preparation of the first flood risk management plans and their subsequent revisions and updates were coordinated at the international level through the Commission for Cross-Border Waters and the Danube River Basin through the International Commission for the Protection of the Danube River (ICPDR). The scope and timetable for the design of the first flood risk management plans is available on the website of the Ministry of Environment of the Slovak Republic in the section on flood protection.

1.4 Assessment of Flood Damage

31

1.4 Assessment of Flood Damage The consequences of floods can take many forms, such as material damage, personal injury and death, cattle mortality, or environmental contamination. In general, flood damage is defined in Sec. 2 subsec. 6) of SR Law No. 7/2010 Coll. on flood protection, as the damage caused by the floods to (a) the state, higher territorial units, municipalities, and persons in terms of • property owned, administered, or used during the third degree of flood activity; • buildings in the protected area during the second degree of flood activity, if the damage has been caused by flooding of the area due to the groundwater level being above the terrain surface caused by a long-standing high water state in the watercourse; (b) the manager of significant watercourses, the manager of small watercourses to which the administration was transferred according to a special regulation (Sec. 51, Law No. 364/2004 Coll. on Water, as amended) or to the owner, administrator, or user of the waterworks (Sec. 52, Law No. 364/2004 Coll. on Water, as amended) which are located on the watercourse or in the flooded area during the second degree or third degree of flood activity; (c) the manager of significant watercourses and the administrator of small watercourses with natural water streams during the second degree or third degree of flood activity; or (d) the manager of significant watercourses and the administrator of small watercourses on a water control structure or natural water stream, if the flood damage was caused by sudden overflowing of water from the stream or sudden return of spilled water to the riverbed. Determining the level of total flood damage is particularly desirable for the design of effective flood protection measures. Total damage should be expressed in financial terms, but this causes problems such as the estimation of the destruction of cultural values and the loss of human lives.

1.4.1 Classification of Flood Damage The total damage caused by the floods is mainly used for the purposes of compensation for flood damage (MoE SR Decree No. 251/2010 Coll.), for international comparisons, as well as for the statistics dealing with damage caused by floods and other natural disasters. It is not possible to express objectively (i.e., exactly accurately) the damage caused by floods, mainly because we cannot assess a significant part of the damage, or the valuation techniques are so complicated that they are

32

1 Flood Risk Assessment—State of the Art

ˇ abandoned. Division of flood damage can be done in different ways. Camrová et al. (2006), for instance, suggested the division of flood damage into • direct damage and • indirect damage. A clear categorization of flood damage is illustrated in Fig. 1.12. ˇ From a general perspective, flood damage can be divided into (Camrová et al. 2006) (a) Losses in human lives (social damage). (b) Damage to the environment (environmental damage). (c) Property damage (economic damage). In the following, the separate damages are described separately.

ˇ Fig. 1.12 Categorization of flood damage adjusted according to (arranged according to Camrová et al. 2006)

1.4 Assessment of Flood Damage

33

Fig. 1.13 Model factors influencing mortality in floods (arranged according to Ministry of Agriculture of the Czech Republic 2004)

(a) Losses in human lives With regard to the loss of human life during floods, these are losses mainly due to the failure of information and warning systems or due to the lack of discipline and risk-taking by individuals. The number of deaths in a flooded area depends mainly on the number of inhabitants living in the area. Water flow and water level increase are flood factors (Fig. 1.13) which can be the direct cause of death. So are other ˇ territorial factors, such as the collapse of buildings due to running water (Camrová et al. 2006; Czech Ministry of the Environment 2004). (b) Damage to the environment The environment and its natural values can also be affected by floods, even though flooding is to a certain extent a natural phenomenon. Although natural flooding is essentially harmless (outside of urbanized areas), it can pollute the area and cause environmental damage. For example, as a result of flooding, leakage and spillage of waste water and fertilizer can occur, which may at best contribute to eutrophication, but is otherwise damaging to certain ecosystems. The impacts of floods that are caused, for example, by the breach of a levee or dam or by deforestation in the river basin are considered undesirable. Floods themselves can affect the environment and nature, but so also can flood protection measures. These impacts can be both negative and positive. Renewal of wetlands and forests in retention areas can be considered positive, for example, to preserve natural values. However, the construction of large reservoirs and other protective structures will have negative effects on the environment as well (Ministry of Agriculture of the Czech Republic 2004). Some damage to the environment can be included in economic damage (e.g., in “watercourse damage” categories). A non-quantifiable part of environmental damage is the release of harmful substances which can affect ecosystems in many forms after ˇ a flood (Camrová et al. 2006).

34

1 Flood Risk Assessment—State of the Art

Fig. 1.14 Factors affecting the extent of economic damage (arranged according to Ministry of Agriculture of the Czech Republic 2004)

(c) Property damage At present, attention is paid mainly to property damage (economic damage). The extent of economic losses depends primarily on the coordination of flood and territorial factors (Fig. 1.14) and consists, as already mentioned, of direct and indirect damages. Direct damage consists mainly of property damage. Indirect damage can include, for example, the loss of work or business. (Ministry of Agriculture of the Czech Republic 2004). The total volume of quantifiable economic damage can be classified according to ˇ several criteria (Camrová et al. 2006). • Depending on the damaged property, the following are distinguished: – Damage to public property administered by state or local self-government. – Damage to private property (citizens or businesses). • Depending on the type of property, damage is classified as follows: – – – – – – –

Buildings, halls, and constructions. Machinery and equipment, means of transport, and inventory. Other constructions. Residential blocks and family houses (suitable for repair). Civil engineering and networks. Watercourses. Residential blocks and family houses completely destroyed (designated for demolition). – Permanent grassland and agricultural production. – Other damage. • Depending on the place of origin (municipalities, districts, and counties).

1.4 Assessment of Flood Damage

35

Flood damage monitoring according to these criteria has its irreplaceable importance for estimating the cost of flood rehabilitation as well as for flood protection measures.

1.4.2 Factors Affecting the Amount of Flood Damage The total value of flood damage is influenced by a number of factors, of which the ˇ most important are (Camrová et al. 2006) as follows: • • • • • • • •

the course of the flood, accurate information on flood hazard (flood warning systems), operational management of water control processes during floods, preparedness and level of implemented flood protection measures, capacity and state of watercourses, urbanization and land use in the flooded area, the ability of the land to retain water, and citizens’ good readiness and awareness of the potential dangers and practices to minimize risks.

As far as the course of a flood is concerned, it is very little influenced by humans, and in part cannot be influenced by humans at all. In general, the higher the flow rate and the greater the volume of flooding, the greater the property damage. The capacity and state of watercourses influence the course of floods in the landscape and have an indirect impact on the overall water catchment capacity of the catchment area. The public is confronted with the question of whether and, if so, which of the variants of watercourse maintenance reduces flood damage. A solution to this dilemma may often be the approach to water flow management which by technical regulation would protect human lives and property in urbanized areas, and by using naturally consistent approaches would allow the spillage of water in open country. In this way, it is possible to partially reduce the flood damage in the built-up areas of municipalities at the expense of the flooding of economically.

References Act No. 7/2010 On protection against floods. (in Slovak) Van Alphen J, Martini F, Loat R, Slomp R, Passchier R (2009) Flood risk mapping in Europe, experiences and best practices. J Flood Risk Manag 2(4):285–292 Apel H, Aronica GT, Kreibich H, Theike AH (2009) Flood risk analyses–how detailed do we need to be? Nat Hazards 49(1):79–98 Baˇcík M, Babiaková G, Halmo N, Lukáˇc M (2006) European legal documents on flood protection and their implementation in the Slovak Republic (in Slovak). Vodohospodársky spravodajca 9–0 Baˇcík M, Halmo N, Pešek V (2009) Preparation of a new flood protection act. Ministry of Environment of the Slovak Republic (in Slovak)

36

1 Flood Risk Assessment—State of the Art

Baˇcík M, Mišík M, Kuˇcera M. (2005) Use of mathematical models and tools of hydroinformatics in flood risk management (in Slovak) http://www.dhi.sk/publikacie/WHR-ManazementPovodnov ychRizik-Sk.pdf Barredo JI, De Roo A, Lavalle C (2007) Flood risk mapping at European scale. Water Sci Technol 56(4):11–17 Bouma JJ, Francoi D, Troch P (2005) Risk assessment and water management. Environ Model Softw 20(2):141–151 Cihláˇr J et al (2010) The first findings from the processing of flood hazard maps and flood risks in the Czech Republic—pilot project (in Czech). In: Proceedings of conference of the Floods 2010: causes, course and experience: contributions from the conference with international participation. Štrbské Pleso—Bratislava: Water Research Institute Cipová K (2010) Implementation of Directive 2007/60/ EC of the European Parliament and of the Council on the assessment and management of flood risks, risk map of Levice. http://www.zzvh. sk/data/files/71.pdf (in Slovak) COM (2003) (Commission of the European Communities) (2003) Best practices on flood prevention, protection and mitigation. Commission of the European Communities, Brussels, 29 p http:// ec.europa.eu/environment/water/flood_risk/key_docs.htm COM (2004) Flood Risk Management, Flood Prevention, Protection and Mitigation. Communication from the Commission to the Council, the European Parliament, the European Economic and Social Committee and the Committee of the Regions. COM (2004) 472 final. Brussels ˇ Camrová L, Jílková J et al (2006) Flood damage and tools to reduce it (in Czech). Prague: IEEP, Institute for Economic and Environmental Policy at the University of Economics, Prague FNH VŠE in Prague. ISBN 80–86684–35–0 Damm M, Fekete A, Bogardi JJ (2010) Intersectoral vulnerability indices as tools to framing risk mitigation measures and spatial planning. In: Conference Proc. HydroPredict, Prague Decree of the Ministry of the Environment of the Slovak Republic No. 112/2011 Laying down details on the content, review and updating of flood risk management plans (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No. 204/2010 Laying down the details of the implementation of the flood forecasting service. (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No.251/2010 Laying down details on the evaluation of expenditures for flood protection work, flood rescue work and flood damage. (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No. 252/2010 Laying down details on the submission of interim reports on the flood situation and summary reports on the course of floods, their consequences and measures taken. (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No. 261/2010 Laying down details on the content of flood plans and the procedure for their approval. (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No. 313/2010 Laying down the details of the preliminary flood risk assessment and its evaluation and updating. (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No. 419/2010 Laying down details on the preparation of flood hazard maps and flood risk maps, on the reimbursement of expenditures for their preparation, review and updating, and on the design and display of the extent of the inundation area on maps. (in Slovak) DEFRA (Department for Environment, Food & Rural) (2000) Guidelines for environmental risk assessment and management. London Directive 2000/60/ EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. (in Slovak) Directive 2007/60/ EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks. (in Slovak) Dráb A (2006) Analysis of flood risks in the process of spatial planning using GIS (in Czech). Urbanizmus a územní rozvoj 9(15):37–42

References

37

ˇ Dráb A, Ríha J (2001) Application of risk analysis in assessment of flood control measures (in Czech). Manuscript at WORKSHOP 2001, In: Extreme hydrological phenomena in River Basins. Prague Drbal K et al (2005) Proposal of methodology of flood risk and damage assessment in flood plain and its verification in the Elbe river basin (in Czech). VÚV TGM Brno. 150 p Drbal K et al (2008) Methodology of flood risk and damage assessment in flood plains (in Czech). Water Research Institute T.G, Masaryk, Brno, p 72 Drobne S, Lisec A (2009) Multi-attribute decision analysis in GIS: weight linear combination and ordered weighted averaging. Slovenia. http://www.informatica.si/PDF/33-4/13_Drobne%20-% 20Multi-attribute%20decision%20analysis%20in%20GIS.pdf EXCIMAP (European exchange circle on flood mapping) (2007a) Atlas of flood maps. Flood mapping: a core component of flood risk management: Great Britain. http://ec.europa.eu/enviro nment/water/flood_risk/flood_atlas/countries/pdf/uk.pdf Fencík R, Danek L, Daneková J (2011) Utilization of GIS applications and hydrodynamic modeling in the creation of flood maps (in Slovak). GIS Ostrava. http://gis.vsb.cz/GIS_Ostrava/GIS_Ova_ 2011/sbornik/papers/Danekova.pdf Ganoulis J (2003) Risk-based floodplain management: a case study from Greece. Int J River Basin Manag 1:41–47 Gozora V (2000) Crisis management (in Czech). Nitra: SPU, 182 p. ISBN 807137-802-X Hald A (1984) A. de Moivre: ‘De Mensura Sortis’ or ‘On the Measurement of Chance’. Int Stat Rev 52(3):229–262 Hardmeyer K, Spence MA (2007) Bootstrap methods: another look at the Jackknife and geographic information systems to assess flooding problems in an urban watershed in Rhode Island. Environ Manag 39:563–574 Havlík A, Salaj M (2008) Analysis and mapping of flood risks (in Czech) http://www.asb-portal.cz/ inzenyrske-stavby/vodohospodarske-stavby/analyza-a-mapovani-povodnovych-rizik-596.html Hofierka J (2003) Geographical information systems and DPZ PU, 2003. [online]. (in Slovak) Horský M (2008) Methods of evaluation of potential flood damage and their application by means of GIS (in Czech). Dissertation thesis. Prague. 124 p Hˇrebíˇcek J, Pospíšil Z, Urbánek J (2010) Introduction to mathematical modeling using Maple (in Czech). Brno, ISBN 978-80-7204-691-1 Chandran R, Joisy MB (2009) Flood hazard mapping of Vamanapuram river basin—a case study. In: 10th Conference on technological trend http://117.211.100.42:8180/jspui/bitstream/123456 789/572/1/CE_HE_05.pdf ICPDR (International Commission for the Protection of the Danube River) (2009) Flood Action Plan for the Vah, Hron and Ipel Rivers Basin. ICPDR Vienna, 31 p ICPDR (2004) Flood Action Program¬me. Action Programme for Sustainable Flood Protection in the Danube River Basin. ICPRD, Vienna, 26 p IKSR (Internationale Kommissionzum Schutz des Rheis). (2005) Action Plan Floods 1995–2005— Action Targets, Implementation and Results. Internationale Kommission zum Schutz des Rheins (IKSR), Koblenz, 16 p International Office for Water (2005) France—ecologic, Germany: evaluation of the impacts of floods and associated protection policies, Paris – Berlin Kandilioti G, Makropoulos CH (2012) Preliminary flood risk assessment. Case Athens Nat Hazards 61(2):441–468 Kandráˇc P (2011) Risk (in Slovak). http://web.tuke.sk/lf-klp/Kandrac%20Peter/MLPB/Tema%20c. 7%20Bezpecnost%20LP-%20denne%20studium/Riziko.docx Karmakar S, Slobodan P, Simonovic AP, Black J (2010) An information system for risk-vulnerability assessment to flood. J Geogr Inf Syst 2:129–146 Kok M, Huizinga HJ, Vrouwenfelder ACWM, Barendregt A (2004) Standard Method 2004. Damage and Casualties caused by Flooding. Highway and Hydraulic Engineering Department Konviˇcka M et al (2002) City and flood—strategy of urban development after floods (in Czech). ERA group spol, Brno, p 217

38

1 Flood Risk Assessment—State of the Art

Korytárová J, Šlezinger M, Uhmanová H (2007) Determination of potential damage to representatives of real estate property in areas afflicted by flooding. J Hydrol Hydromech 55(4):282–285 Kron W (2005) Flood Risk = Hazard•Values•Vulnerability. Water Int. 30(1):58–68 Kudrnová L, Hanzl A, Bureš K (2004) Pilsen region, concept of water protection. Study of Flood Measures E (in Czech). Economic Analysis. Prague: Hydroprojekt CZ, a.s Kutiš V (2006) Basics of modeling and simulations (in Slovak). Bratislava. 136 p http://www.ene rgetici.tym.sk/system/docasne/upni_60.pdf Langhammer J (2007) Floods and landscape changes (in Czech). Charles University in Prague a ME CZ, Faculty of Natural Sciences Langhammer J (2010) Current approaches to flood risk assessment and modeling (in Czech). http:// web.natur.cuni.cz/geografie/vzgr/monografie/povodne/povodne_langhammer.pdf LAWA (1996) Hochwassergefahr. Vor¬beugen – Schäden vermeiden. LAWA, Berlin. 4 p LAWA (2000) Wirksamkeit von Hochwasswasservorsorge- und Ho-chwasservorsorgemassnahmen. LAWA, Schwerin, p 10 LAWA (2010) Recommendations for establishment of flood risk management plans. LAWA, Dresden, p 58 Máca J, Leitner B (2002) Operational analysis for security management (in Slovak). Learning text. Faculty of Special Engineering—Detached workplace Košice. 178 p Máca J, Leitner B (2006) Application of multi-criteria decision-making methods in crisis management (in Slovak). Faculty of Special Engineering—Detached workplace Košice. p 1–9 Malczewski J (2006) GIS-based Multicriteria decision analysis: a survey of literature. Int J Geogr Inf Sci, 703–726 Meyer V, Haase D, Scheuer S (2007) GIS-based multicriteria analysis as decision support in flood risk management. UFZ—Discussion papers. Department of Economics 6: 57 p Meyer V, Messner F (2005) National flood damage evaluation methods, a review of applied methods in England, the Nederland, the Czech Republic and Germany. UFZ, Department of Economics Meyer V, Scheuer S, Haase D (2009) A multicriteria approach for flood risk mapping exemplified at the Mulde river Germany. Nat Hazards 48(1):17–39 Míka VT (2009) Social risks as a problem of crisis management. Proceedings of the international scientific conference “Crisis Management in a Specific Environment”. Žilina: FŠI TU, pp 469– 474. ISBN 978-80-554-0016-7 (in Slovak) Mišík M, Kuˇcera AM, Ando M (2011b) Flood modeling and mapping of urbanˇ ized areas (in Slovak). In: River basin and flood risk management 2011, Castá Papierniˇcka http://www.vuvh.sk/download/ManazmentPovodi_rizik/zbornikPrispevkov/Konfer encia/Prispevky/SekciaA/Misik_Kucera_Ando.pdf Mišík M, Kuˇcera AM, Ando M, Stoklas M (2011a) Flood mapping of large areas (in Slovak). ˇ In: River basin and flood risk management 2011, Castá Papierniˇcka http://www.vuvh.sk/dow nload/ManazmentPovodi_rizik/zbornikPrispevkov/Konferencia/Prispevky/SekciaA/Misik_Kuc era_Ando_Stoklasa.pdf MoE SR (2011e) Analysis of the state of flood protection in the territory of the Slovak Republic. Summary of analysis results. Annex 1. http://www.minzp.sk/files/sekcia-vod/priloha_1-suhrn_ vysledkov_analyzy.pdf MoE SR (2012) Water Management in the Slovak Republic in 2011, Bratislava, 2012. (in Slovak) MoE SR (2012a) Report on the course and consequences of floods in the Slovak Republic from 1 January to 30 April 2012. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/ sprava-o-priebehu-a-nasledkoch-povodni-v-sr-v-obdobi-januar-az-april-2012.pdf (in Slovak) MoE SR (2012b) Report on the course and consequences of floods in the Slovak Republic in the period from 1 May to 31 August 2012. http://www.minzp.sk/files/sekcia-vod/povodne-20022012-informacie/sprava-o-priebehu-a-nasledkoch-povodni-v-sr-v-obdobi-maj-az-august-2012. pdf (in Slovak)

References

39

MoE SR (2012c) Annex to the Report on the course and consequences of floods in the territory of the Slovak Republic from 1 January to 30 April 2012 (table part). http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/suhrnne-info-o-pri ebehu-a-nasledkoch-povodni-2012.pdf (in Slovak) MoF SR (Ministry of Finance of the Slovak Republic) (2013) Reference rate, discount rate and interest rates for State aid recovery. http://www.finance.gov.sk/Default.aspx?CatID=5415 (in Slovak) Nascimento N, Baptista M, Silva A et al (2006) Flood-damage curves: Methodological development for the Brazilian context. Federal University of Minas Gerais. Water Practice & Technology, 1(1). IWA Publishing, ISSN 1751-231X Ocelíková E (2004) Multicriterial decision making (in Slovak), 2nd edn. Elfa s r.o, Košice, p 87 Penning-Rosell E, Floyd Ramsbottom D, Surendran S (2005) Estimating injury and loss of life in floods: a deterministic framework. Nat Hazards 36:43–64 Rozsypal A (2003) Engineering constructions (in Czech). Risk management. Bratislava: JAGA GROUP, s.r.o. 174 p. ISBN 987-80-8076-066-3 ˇ Ríha J et al (2005) Risk analysis of flood areas (in Czech). Work and studies of the Institute of Water Structures FAST VUT v Brnˇe, Sešit 7, CERM, Brno, 286 p. ISBN 80-7204-404-4 Satrapa L (1999) Design and use of methodology for determination of potential flood damage (in Czech). In: Flood damage—determination of potential damage caused by floods. Prague, ˇ CVTVHS, Part 1, pp 73–91. ISBN 80-02-01274-7 Satrapa L, Fošumpaur P, Horský M et al. (2011) Assessing the effectiveness of flood protection actions in the framework of the activities of the strategic expert of the Flood Prevention Program in the Czech Republic (in Czech). In: River Basin and Flood Risk Management 2011—Proceedings ˇ of the Scientific Conference. Castá Papierniˇcka—Bratislava, Water Research Institute Scheuer S, Haase D, Meyer (2011) Exploring multicriteria flood vulnerability by integrating economic, social and ecological dimensions of flood risk and coping capacity: from a starting point view towards an end point view of vulnerability. Nat Hazards 58(2):731–751 Skubiˇcan P (2012) Identification, evaluation and mapping of flood risk in GIS environment using spatial multi-criteria analysis (in Czech). In: GIS Ostrava 2012—Current challenges of geoinformatics, pp 1–14 http://gis.vsb.cz/GIS_Ostrava/GIS_Ova_2012/sbornik/papers/skubin can.pdf Skubiˇcan P (2010) Spatial multicriteria analysis for decision support (in Slovak). In: Proceedings of scientific works of PhD students and young researchers“Mladí vedci 2010”, pp 1–9 Smejkal V, Rais K (2006) Risk management in companies and other organizations (in Slovak). Second, Upgraded and Extended Edition. Grada Publishing, a.s., 296 p. ISBN 80-247-1667- 4 Smith K (1996) Environmental hazards. London (Routledge) Solín Lˇ (2011) Flood risk assessment—current state of research (in Slovak). In: River Basin and ˇ Flood Risk Management 2011-Proceedings of the Scientific Conference.Castá Papierniˇcka – Bratislava, Water Research Institute ˇ Martinˇcáková M (2007) Some remarks on methodology of flood maps creation in Slovakia Solín L, (in Slovak). Geogr J 59(2):131–158 ˇ Skubiˇcan P (2013) Flood risk assessment and management: review of concepts, definitions Solín L, and methods (in Slovak). Geogr J 66(1):23–44 Szolgay J (2010) Principles of flood protection in international documents (in Slovak). In: Urbanity. http://www.urbion.sk/ww2/wp-content/uploads/2011/01/urbanita_410_web.pdf Šimák L (2001) Crisis management in public administration (in Slovak). Žilina: ŽU, 243 p. ISBN 80-88829-13-5 Tanavud CH, Yongchalermchai CH, Bennui A, Densreeserekul O (2004) Assessment of flood risk in Hat Yai Municipality, Southern Thailand, using GIS. J. Nat. Disaster Sci. 26(1):1–14 Tichý M (1994) Risk ingineering. 1—Risk and its estimation. Constr Superv 9:261–262 Tichý M (2006) Risk management: Analysis and management (in Slovak). Publishing CH Beck, 396. ISBN 80-7179-415-5 (in Czech)

40

1 Flood Risk Assessment—State of the Art

Tran P, Shaw R, Chantry G, Norton J (2009) GIS and local knowledge in disaster management: a case study of flood risk mapping in Vietnam. Disasters 33(1):152–169 Tuˇcek J (1998) Geographical information systems—Principles and practice (in Slovak). Computer Press UN/ISDR (United Nations International Strategy for Disaster Reduction) (2004) Living with Risk, A Global Review of Disaster Reduction Initiatives. 430 p Valenta P (2005) Use of numerical models of water flow in flood protection (in Czech). CVTU, Habilitation lectures Yahaya S, Ahmad N, Abdalla FR (2010) Multicriteria Analysis for Flood Vulnerable Areas in Hadejia-Jama’are River Basin. Nigeria. Eur. J. Sci. Res. 42(1):71–83 Yalcin G, Akyurek Z (2004) Analysing flood vulnerable areas with multicriteria evaluation. XXth ISPRS Congress, Geo-Imagery Bridging Continents, In, pp 359–364 Zeleˇnáková M (2009) Flood risk assessment (in Slovak). Košice: Technical University of Košice, Faculty of Civil Engineering, ISBN 978-553-0315-4

Chapter 2

Materials and Methods

Floods endanger the lives and health of the population, cultural heritage, and the environment while damaging property and limiting economic activity. They cannot be prevented, but we can estimate the extent of flood risks and take effective measures to mitigate their adverse consequences. Flood protection is a society-wide task. The basic rules for flood prevention are laid down in the secondary EU law—Directive 2007/60/EC of the European Parliament and of the Council on the assessment and management of flood risks, which, as mentioned above, is transposed into the legal order of the Slovak Republic by Law No. 7/2010 Coll. on Flood Protection and generally binding regulations setting out the details of its implementation (Sect. 1.3). The main objective of the work is to propose a procedure for selecting an effective form of flood protection (risk management) in order to reduce an identified flood risk (risk assessment). Figure 2.1 shows a simplified schematic diagram of the process, of the individual steps of the work—flood risk assessment and flood risk management. Flood risk management is a decision-making process following the results of the flood risk assessment process (Fig. 2.1). The goal of this process is to propose an optimal way of reducing the risk to an acceptable level. The entire process of flood risk management is described in the following chapters.

2.1 Calculation of Potential Flood Damage Potential flood damage concerns both movable and immovable properties and variously defined natural and landscape values in the floodplain area. This chapter details the procedures for determining each category of potential flood damage. The following damage categories are considered and evaluated, as stated in Sect. 1.4.1:

© Springer Nature Switzerland AG 2020 M. Zeleˇnáková et al., Flood Damage Assessment and Management, Water Science and Technology Library 94, https://doi.org/10.1007/978-3-030-50053-5_2

41

42

2 Materials and Methods

Fig. 2.1 Structure of the work

• Damage to property, • Damage to the environment, and • Damage to human life. The number of human casualties and the amount of environmental and economic damage are three basic indicators that assess the extent and severity of a flood event. The assessment of potential flood damage enables the selection of effective flood protection measures. The main reason for calculating potential flood damage is the proposal of a procedure for selecting the most cost-effective combinations of measures needed to reduce the impact of floods on human health, the environment, and their assets, which will serve as a basis for drawing up flood risk management plans. The essence is to create a conceptual framework that can and must be adapted to the nature and needs of each river basin. This will ensure a consistent approach and the necessary effectiveness in preparing flood risk management plans, as required by Directive 2007/60/EC on the assessment and management of flood risks. The calculation of individual damage categories requires a separate approach and different inputs, as described in the following subchapters.

2.1 Calculation of Potential Flood Damage

43

2.1.1 Property Damage The issue of assessment of potential flood damage to property is very well addressed in the Czech Republic and in a dissertation (Horský 2008), which was followed in the same year in the design of a “Methodology for determining flood risks and damage in the flood zone” (Drbal et al. 2008). Direct potential flood damage is determined in these publications by a procedure based on the application of damage curves, respectively, loss curves—the “level I” and “level II” methods. Due to the very similar building and infrastructure solutions in the Slovak and Czech Republics, the methodology proposed in the Czech Republic is used in a modified form for the calculation of property damage in this work. The methodology can be applied in any other country, as well. However, the available work bases permitted only the use of the “level I” method, which is the fastest method used in larger territorial units and is not so demanding with regard to inputs. If a more detailed background is available, it’s possible to use the “level II” method for calculating flood damage, which uses available input data and is processed in mentioned dissertation (Horský 2008). The “level II” method is essentially an extension of the basic “level I” method in some areas of evaluation. Potential direct flood damage is determined by the “level I” method based on the application of loss curves, which are based on the acquisition prices of the individual categories of objects considered and the loss-making functions created by detailed analysis of a flood’s effects on the individual categories of objects and the parts of their construction, according to the structure of the building components and the classification of construction sites (Drbal et al. 2008). The difference is in the acquisition prices, which are derived from the average budget price per unit of measure in the construction industry by the Association of Landscape Architects (UNIKA) and the Institute of Building Economics (2012). For calculation of direct potential flood damage to property, a general relationship is used (Horský 2008), which is modified in the following form (2.1): DPik = Sik Pk L k

(2.1)

where DPik i k S P L

the value of the quantified damage of the given object i in the category k [e], the object index in the given category k, the index of each of the rated categories described below, size or amount of the affected object by category [pcs, m, m2 , m3 ], unit price per unit of measure per rated category [e/pc; e/m; e/m2 ; e/m3 ], and the loss for each category, expressed in terms of flooding or, respectively, depth of flooding [%].

44

2 Materials and Methods

The basic principle of calculation for each damage category is still the same; the difference is only in units of measure and their prices, where the objects are generally calculated in length units [m] in the case of engineering networks, units of built space [m3 ] in the case of buildings, and in area units [m2 ] in the case of agricultural land. Each loss curve is expressed in a range of potential damage values. The upper and lower damage limits are used due to the different possibilities of applying faults of individual parts of a structure to the resulting damage. The loss curves used in the calculation can be of a dual type (Drbal et al. 2011): • Dependent on the depth of flooding in building objects and • Independent of the depth of flooding—engineering networks, infrastructure, and agriculture. Property damage is calculated for each category according to the following relationship (2.2): DPk =



DPik

(2.2)

where DPk the value of the quantified damage in the category to [e] and DPik the value of the quantified damage of the given object also in the category of [e]. Then the total damage to property in the evaluated territory is calculated as the sum of the losses of the individual asset categories for the given QN , as follows (2.3): DM =



DMk

(2.3)

where DM value of the total quantified damage to the asset [e] and DMk the value of the assessed damage in the category k [e]. Data and procedures for the determination of potential flood damage of assets and by category of buildings (buildings and civil engineering works) are described in the following, and their unit and loss rates are determined. The breakdown of buildings (objects) into these categories is taken from the Proposals for the Average Budget Price per Unit of Measure for 2012 (UNIKA 2012). An assessment of potential flood damage to property is also the assessment of agricultural damage to plant production. A. Damage to buildings In the case of the “level I” method, only one type of building is distinguished, with the underlying elements being • flood maps for individual QN , • building layer, and • map of depths in flooded areas.

2.1 Calculation of Potential Flood Damage

45

Building damage is calculated according to relationship (2.4): DB =



(Ai PB L i (h))

(2.4)

where DB value of the assessed damage to buildings [e], area of the polygon of the building i [m2 ], Ai L i (h) the loss value expressed from the loss function for a given depth of flooding in the vicinity of building i (minimum and maximum) [-] (see Table 2.1, Fig. 2.2), and unit (acquisition) price of 1 m2 of a one-storey building [e/m2 ] (Table 2.2). PB In calculating the damage, for simplification it is considered that these are always multi-storey buildings, with a standard floor height of about 3 m. Non-zero loss at zero depth is a loss for underbuilt buildings. The layout curve for buildings is shown graphically in Fig. 2.2 and in tabular form in Table 2.1 (Horský 2008). Table 2.1 Percentage of maximum (Lmax) and minimum loss (Lmin) on buildings depending on the depth of the flood (h) (Horský 2008) Depth of flood h [m]

0

1

2

3

4

5

12.69

17.15

20.38

21.89

28.98

34.84

Minimum loss Lmin [%]

2.23

6.69

3.55

10.64

9.93

Maximum loss L max [%]

16.5

Fig. 2.2 Universal loss curve expressing the maximum and minimum damage (or loss) of buildings on the basis of the depth of flood (h) (arranged according to Horský 2008)

46

2 Materials and Methods

Table 2.2 Building price indices for 2012 and averaging [e/m2 ] Building type

Abbreviation

Price [e/m2 ]

Residential buildings

PBr

174.10 (average)

Non-residential buildings

PBn

176.05 (average)

Average cost per unit of space [e/m2 ]

175.08

Floor height [m] Acquisition cost per floor area unit at floor height of 3 m [e/m2 ]

3 PB

525.24

The unit price for buildings is derived as the average of price indices in construction. The price indices for each building type are the prices per m3 of obsolete space, which are derived from the Proposals for the Average Budget Price per Unit of Measure (UNIKA 2012)-9. The building categories and price indices are listed in Table 2.2. B. Damage to infrastructure For damage to infrastructure using the “level I” method, damage to roads, railways and utility networks, and bridges are considered. The necessary data are as follows: • • • •

flood maps for individual QN , road infrastructure layer, rail layers, and bridges layer.

B1. Road infrastructure According to Slovak technical standard STN 73 6100, road infrastructure is a road intended primarily for the movement of vehicles, cyclists, and pedestrians. Depending on the transport significance and technical value, roads are classified as follows: • Road infrastructure—a road intended for the movement of road vehicles predominantly outside of urban areas, characterized by reinforced roadways including motorways; expressways; and first, second, and third class roads. • Local infrastructure—a road that is part of the transport facilities for a particular residential unit or creates a transport connection in its area of interest. • Purpose-built infrastructure—a road enabling the transport connection of a production plant, closed premises, lone buildings, with the road network, e.g., as well as a forest and forest roads or creating transport links within enclosed spaces and facilities. According to the transport significance, destination and technical equipment, and according to Law no. 368/2013 Coll. on Road Infrastructure, roads are divided into

2.1 Calculation of Potential Flood Damage Table 2.3 Replacement width assigned to each type of roadway (STN 73 6101)

Type of road

Width [m]

Motorways, expressways

24.5 (average)

First and second class roads

11.5 (average)

Third class, local, and purpose-built roads

• • • •

47

7.5 (average)

Highways, Trunk roads, Local roads, and Purpose-built roads.

Road damage results from the total flooded area of all roads [m2 ] imputed to the loss value for the given QN by relation (2.5): D R I = AL PR I

(2.5)

where DRI damage to roads [e], A area of roads [m2 ] converted over replacement areas, and 2 LPRI loss price [e/m ] minimum and maximum (Table 2.6). In the case of linear objects such as roads, it is necessary to add a new parameter “width,” which is missing for linear objects, before calculating the damage, according to Table 2.3. Replacement widths are determined in accordance with STN 73 6101 on road and highway design. B2. Railways Railway damage is based on the total length of the flooded railways [m] multiplied by the loss in euro per meter of length for the given QN, according to relationship (2.6): D RW = L L PRW

(2.6)

where DRW damage on railways [e], L railway length [m], and LPRW -loss price [e/m] minimum and maximum (Table 2.6). The cost of determining losses on roads and railways is based on price indicators in construction. The price indices for each type of transport link are prices per m in the case of railways and the price per m2 of surface area for roads. Prices are derived from the Proposals for the Average Budget Price per Unit of Measure (UNIKA 2012)-9. Table 2.4 shows the Categories of Civil Engineering Constructions (related to Roadways and National Railways). The minimum and maximum damage values are taken from Horský (2008).

48

2 Materials and Methods

Table 2.4 Roads and railways price indicators and calculation of loss price Title

Roads Railways

Price [e/m2 ] [e/m]

Damage [%]

Loss price

Min

Max

Labeling

Unit

88.16

2.06

4.12

SC CK

[e/m2 ]

1.82

3.63

591.31

5.80

9.07

SC Ž

[e/m]

34.30

53.63

Min

Max

B3. Infrastructure networks Damage to infrastructure networks is calculated for all types of networks, with damage foreseen for networks built up alongside roads. The damage count is based on the total length of flooded networks (infrastructure). The length value is multiplied by the loss value in EUR per meter of length for a given QN by relation (2.7): DEN = L L PEN

(2.7)

where DEN damage to infrastructure networks [e], L length of networks or length of roads [m], and LPEN loss price [e/m]—minimum and maximum (Table 2.7). The cost for determining losses on infrastructure networks is based on price indices of the networks. Unit prices for individual networks are prices of a fixed and variable portion of the indicator per meter. Prices are calculated as the average prices for each of the indicators obtained from the publication “Budget Benchmarks Cenekon” and are presented in Table 2.5. The minimum and maximum damage values are taken from Horský (2008). The calculation assumes that the territory is equipped with all kinds of networks, so the average cost of the LPEN is used for the calculation. If it is known that one or more of the networks is missing in the territory, the calculation can only be made for existing networks, using the sum of the loss rates of the existing networks. Table 2.5 Costs for infrastructure networks and calculation of losses Title

Price [e/m]

Damage (%) Min

Loss price [e/m]

Max

Min

Max

Electricity

60.10

0.33

0.98

SC EN1

0.20

0.59

Water supply

85.08

0.35

0.39

SC EN2

0.30

0.33

Sewers

110.84

0.50

0.52

SC EN3

0.55

0.57

Gas

177.98

2.00

2.00

SC EN4

3.56

3.56

29.98

0.77

2.31

SC EN5

0.23

0.69

SC EN

4.84

5.74

Telecommunications Total

2.1 Calculation of Potential Flood Damage Table 2.6 Lengths and widths for bridges and walkways

49

Type

Length (l)

Width (w)

Bridge—line

Actual line length

10

Bridge—point

Replacement length—4 m

10

Footbridge—line

Actual line length

2

Footbridge—point

Replacement length—2.5 m

2

B4. Bridges The damage to bridges originates from the area of the bridge [m2 ] multiplied by the loss value in euros per meter of length for the given QN according to relationship (2.8): D B = AL PB

(2.8)

where DB damage to the bridge [e], A area of the bridge [m2 ], and LPB -loss price [e/m] minimum and maximum (Table 2.9). The surface of the bridge is calculated as the product of the length (l) and the width (w) of the bridge, which are determined according to Table 2.6. The cost for determining losses on bridges is based on price indicators in civil engineering. The price indices for each type of bridge are the prices per m2 of bridge, which are derived from the Proposals for the Average Budget Price per Unit of Measure (UNIKA 2012). The table for the category of civil engineering construction (Tables 2.6 and 2.7) are taken from Horský (2008). Individual structures are distinguished according to their location or position. If the bridge line is parallel to a railway line, or the point of the bridge lies on the line of a railway track, the bridge is a railway bridge. In other cases, the bridge is considered to be a road bridge or a foot bridge. C. Damage in agriculture Agricultural damage is considered as damage to crop production, calculated as the product of the flooded agricultural area and the loss value determined on the basis of Table 2.7 Costs for bridges and calculation of loss prices Title

Price [e/m]

Damage (%) Min

Loss price [e/m]

Max

Min

Max

Road bridge

1 697.99

1.00

1.40

SC Mo1

17.00

23.77

Railway bridge

3 009.71

1.00

1.40

SC Mo2

30.00

42.14

Foot bridge

1179.16

1.00

1.40

SC Mo3

11.80

16.50

50

2 Materials and Methods

crop yield curves (Horský 2008; Satrapa 1999), according to the following formula (2.9): DCP = AL PCP

(2.9)

where DCP damage to crop production [e], P area of agricultural land [ha], and LPCP -loss price [e/ha] minimum and maximum (Table 2.10). The loss price in crop production is based on the average cost of cultivation of basic crops published in Slovakia by the Institute of Agricultural and Food Economics and the average annual loss, which is derived from the distribution of individual crop losses during the year, depending on the arrival of the flood (Satrapa 1999). Table 2.8 and the graph shown in Fig. 2.3 contain data on potential flood damage for selected crop types in individual months of the year, as a percentage of the costs of cultivation (Drbal et al. 2008; Horský 2008; Satrapa 1999). As a percentage of loss and loss per hectare, it should be noted that it is not the weighted average of the minimum and maximum values, but the minimum and maximum of the weighted averages for each month, and accordingly, the loss cost per hectare is LPcpmax and LPcpmin . Frequent changes in crop production and the relatively small share of potential damage to crop production due to total property damage led to an average loss of yield (LOL) for all crops per 1 hectare of cultivated land (Table 2.10). The structure of harvesting areas in percentages and costs of cultivation in euro per hectare are taken from the Research Institute of Agriculture and Food Economics. Growing costs represent the direct costs for 2012. Table 2.8 Calculation of losses for crop production on a 1 ha area (Horský 2008) Crop

Cereals

Rate of the crop areas [%] 56.2

Growing costs Damage [c/o] [e/ha] Min Max

Loss price [e/ha]

599.33 (average)

15

80

SC P1

89.90

479.46

Mark

Min

Max

Sweet corn

8.16

677.35

15

80

SC P2

101.60

541.88

Colza

9.77

908.39

10

90

SC P3

90.84

817.55

Sunflower

6.36

686.17

10

80

SC P4

68.62

548.94

Potato

0.18

3 154.66

20

80

SC P5

630.93

2 523.73

Sugar beet

2.25

1 617.07

15

80

SC P6

242.56

1 293.66

1273.83

20

80

SC CP

254.77

1 019.06

Other Total Average

17.08 100

2.1 Calculation of Potential Flood Damage

51

Fig. 2.3 Potential flood damage for selected crop types in individual months of the year as a percentage of the costs of cultivation (arranged according to Drbal et al. 2008, Horský 2008)

2.1.2 Environmental Damage Prior to the actual assessment of the impacts of floods and environmental damage, the objectives and basic legislation in the study area need to be defined. The most important legislative document in the field of nature and landscape protection in Slovakia is Law No. 543/2002 Coll. on Nature and Landscape Protection, as amended, to contribute to preserving the diversity of living conditions and forms of life on Earth. Protection of nature and the landscape means, pursuant to this Law, the limitation of interventions that may endanger, damage, or destroy the conditions and forms of life, the natural heritage, and the appearance of the country and thus reduce its ecological stability as well as eliminating the consequences of such interventions. A condition of membership in the European Union in the field of nature conservation is the construction of a NATURA 2000 system. NATURA 2000 is the name of a network of protected areas declared according to common criteria. The rarest and most endangered species of plants, animals, and selected types of habitats in the EU are protected. Criteria for territory designation and lists of species and habitats are set out in two EU directives. One is Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (the Habitats Directive) and Council Directive 79/409/EEC on the Conservation of Wild Birds (Birds Directive). These two directives are still the most comprehensive legal norm for nature conservation in the world.

52

2 Materials and Methods

“Environmental damage” means damage to the environment involving a wide range of adverse impacts in connection with floods. According to Law No. 359/2007 Coll. on the Prevention and Remedy of Environmental Damage, as amended, environmental damage is damage to • protected species and protected habitats that have serious adverse effects on the achievement or maintenance of a favorable conservation status of the protected species and protected habitats, with the exception of the previously identified adverse effects resulting from the operator’s conduct, to which he was expressly entitled under a special regulation; • water that has serious adverse effects on the ecological, chemical, or quantitative status of the water or the ecological potential of the waters, with the exception of the adverse effects laid down in a specific regulation; or • soil arising from soil contamination, posing a serious risk of adverse health effects due to the direct or indirect introduction of substances, preparations, organisms, or microorganisms into the soil or subsoil. When estimating any damage to the environment, it is necessary in the first phase to decide whether the damage should be quantified at all. At low damage intensity, damage detection is generally time-consuming and costly, so the cost of quantifying such damage can exceed the final amount representing actual damage. Data basis for the calculation of damage to the environment In evaluating environmental damage from the point of view of flood damage in nature, information on the occurrence of individual potential sources of pollution in the study area as well as on the sources themselves is important. Common databases are as follows: • municipal/town plans (www.uzemneplany.sk), • maps of potential sources of pollution (point, areal), • databases on point sources of pollution (MoE SR 2009c): – KV-ENVIRO, which contains more than 13,004 potential pollution sources. (The basis of this database is the GEOENVIRON database, which contains 9,177 potential point sources of pollution.) There are 2,279 sites, 6,938 landfills, and other sources of pollution. – Register of Environmental Burdens (REB), which is part of the information system (www.enviroportal.sk) built within the project Systematic Identification of Environmental Burdens of the Slovak Republic (www.sazp.sk). It contains 1,819 sites divided into 3 sections: • probable environmental burdens (Part A)—878 sites, • environmental burdens (Part B)—257 sites, and • sanitized and reclaimed environmental burdens, sources of pollution where measures have already been taken or are being implemented to reduce the risk of contamination and the remediation of pollution (Part C).

2.1 Calculation of Potential Flood Damage

53

– Integrated Monitoring of Pollution Sources (IMZZ) database, which contains sources of pollution of dangerous substances on which the State Water Administration has imposed an obligation to monitor their impact on groundwater. This database has been compiled since 2007. Basic philosophy The basic philosophy of environmental damage assessment is that all three assessed components of the environment (protected biotopes, water, and soil) can be damaged by the entire range of hazardous substances released from potential sources of pollution. Attention is therefore given to the quality of water. The development of water quality is dependent on the course of flow during the flood. In most flood situations, a change in water quality is divided into two stages ˇ (Ríha et al. 2005): • In the first stage, the course of pollution is dependent on the flood wave transition. Changes in substance concentrations are given by the cross-sectional velocity and flow rate, describing the transport capacities of the stream and the volume of water describing the rate of dilution. • In the second stage, or in the phase of decreasing flow, the water quality in the streams is affected by the depletion of wastewater treatment plants and industrial pollution sources. The most dangerous and most frequently occurring substances in water at the time ˇ of flooding are (Ríha et al. 2005) as follows: • Petroleum substances can cause skin diseases such as eczema, allergy, or serious damage to the liver; the water is most often from industrial warehouses. • Dioxins are carcinogenic, severely damaging the liver and nervous system; sources are mostly chemical enterprises. • Nitrates bind to red blood cells; the source is water that spreads over fields. • Fecal bacteria causes skin diseases such as rashes and ulcers, resulting in high temperatures and digestive problems; sources are flooded sewage treatment plants and sewer networks. • Mercury is a highly toxic and life-threatening metal; sources are chemical enterprises. • Microorganisms from dead animals cause tularaemia and diarrhea. • Bacteria of leptospirosis cause digestive problems, headaches, and liver damage. Another serious consequence of the floods is the degradation of agricultural and forest soils—flat soil sowing, the reduction of the soil profile on sloping land, and the formation of ravines and depression. As a result of flooding, the original humus horizon overlaps with a layer of gravel, sand, and other drifting material. Erosion and accumulation further cause structural changes and skeletal soils, which aggravate the physical and chemical properties of the soil. The greatest damage to the soil cover occurs especially in the valley sections of the stream, which causes a large dragging force of the water stream. At the top of the streams, floods cause degradation to the

54

2 Materials and Methods

loss of the entire production layer of the soil. The influence of soil properties is most common in the lower and middle parts of the flows. This is mainly due to the supply of additional sediments, the benefits (but also the yield) of chemical substances. Damage to the environment or impact on the environment is classified according to the point method into one of four categories: marginal, small, medium, and large effect (Table 2.11). The starting point for learning the category of consequence is the categorization of potential sources of pollution affecting water quality. At present, there is no complete register of sources of pollution in the Slovak Republic; therefore, a proposal is created for the needs of this work. The different sources of pollution are divided into two main groups: A. Point sources of pollution: A1. Factories with the presence of hazardous substances, A2. Sewage treatment plants, and A3. Fuel filling stations. B. Surface sources of pollution: B1. B2. B3. B4 B5.

Waste landfills, Tailings, Population without sewage systems, Agriculture, and Environmental burdens.

By flooding these objects, leakage and leaching of pollutants can occur and, as a result, the quality of surface and underground water deteriorates, and such soils can lead to ecological disasters such as habitat damage, to fauna and flora, and epidemics. Very serious damage of a long-term nature also relates to groundwater, which is used as a source of drinking water. The next section describes the individual sources of pollution. A.1 Factories with the presence of hazardous substances During a flood, dangerous substances from chemical and industrial plants may escape. Factories with the presence of hazardous substances are categorized according to the total amount of the selected hazardous substance that is present in the plant in accordance with Law No. 277/2005 Coll., amending Law No. 261/2002 Coll. on the Prevention of Major Industrial Accidents. For the purposes of this work, chemicals and chemical preparations which are hazardous to the environment are taken into account. According to Law No. 163/2001 Coll. on Chemical Substances and Chemical Preparations, as amended (Law No. 405/2008 Coll.), the substances and preparations referred to in paragraph 1 (o) of this Law are those which may present an immediate or later danger to one or more components of the environment if they are emitted into the environment. Dangerous substances and preparations are characterized by having one or more dangerous properties, and these properties are classified under the conditions laid down in Directive 67/548/EEC as R-phrases.

2.1 Calculation of Potential Flood Damage

55

The designation of substances and preparations that may cause environmental damage is as follows: • For aquatic environments R50—very toxic to aquatic organisms, R51—toxic to aquatic organisms, R52—harmful to aquatic organisms, and R53—may cause long-term adverse effects in an aquatic environment. • For non-aquatic environments R54—toxic to flora, R55—toxic to fauna, R56—toxic to soil organisms, R57—toxic to bees, R58—may cause long-term adverse effects on the environment, and R59—hazardous to the ozone layer. A combination of specific risks is also used: R50/53—very toxic to aquatic organisms, and may cause long-term adverse effects in an aquatic environment, R51/53—toxic to aquatic organisms, and may cause long-term adverse effects in an aquatic environment, R52/53—harmful to aquatic organisms, and may cause long-term adverse effects in an aquatic environment. According to the Globally Harmonized System (GHS) of classification and labeling of chemicals, a substance dangerous for the environment is marked with the mark shown in Fig. 2.4. Fig. 2.4 Designation of a substance dangerous for the environment under the GHS label (arranged according to RÚVZ 2013)

56

2 Materials and Methods

Table 2.9 Categories of hazardous properties of selected hazardous substances (Law No. 277/2005 Coll.) Classification of the selected dangerous substance

Category of business A

B

Threshold value in tons R50—very toxic substance for aquatic organisms

≥100 < 200

≥200

R51/53—toxic to aquatic organisms may cause long-term adverse effects in an aquatic environment

≥200 < 500

≥500

Companies with the presence of hazardous substances are, in the sense of Law No. 277/2005 Coll., classified into category A or B based on the total amount of dangerous substances present in the enterprise. In this work, businesses are divided according to the threshold values of substances that are dangerous to the environment. Specifically, they are R-vectors: R50 and R51/53 (Table 2.9). The thresholds are taken from the law. A.2 Sewage treatment plants At the time of floods, sludge from wastewater treatment plants and the outflow of untreated wastewater can be discharged and, therefore, a wastewater treatment plant is also a significant source of pollution. According to Law No. 364/2004 Coll. on Water, as amended by Law No. 384/2009 Coll., a wastewater treatment plant is a set of facilities for the treatment of wastewater and special waters before their discharge into surface water or groundwater or before their other use. A decisive indicator for the separation of sewage treatment plants for this work is the amount of pollution generated in the EP (equivalent population), which represents the amount of biodegradable organic pollutants expressed as the BOD5 equivalent of 60 g of BOD5 produced per inhabitant per day (Law No. 384/2009 Coll.). Based on EO, Wastewater Treatment Plants (WWTPs) are divided into four classes for the needs of this work: • • • •

up to 2000 EP, 2000–10,000 EP, 10,000–100,000 EP, and over 100,000 EP.

A.3 Fuel filling stations Other point sources of pollution include fuel filling stations located near watercourses, in floodplains. During the flooding of filling stations, fuel (gasoline, diesel) can be released and consequently cause damage to the environment, in particular by oil. Fuel is toxic to aquatic organisms and may cause long-term adverse effects in an aquatic environment.

2.1 Calculation of Potential Flood Damage

57

B.1 Waste landfills Waste landfills are included among diffuse sources of pollution. When landfills are flooded, waste material is discharged and spreads into the surrounding area. According to Law No. 409/2006 Coll., as amended, a landfill site is a waste disposal site where waste is permanently deposited on the surface of the ground or in the ground. Waste landfill is also considered to be a place where the waste producer carries out waste disposal at the site of production (internal landfill) as well as a place that has lasted for more than 1 year for the temporary storage of waste. According to the material deposited, landfills are divided into • waste landfills for inert waste, • landfills for non-hazardous waste, and • landfills for hazardous waste. Hazardous wastes are those which have one or more of the hazardous properties listed in Annex. 4 of Law No. 409/2006 Coll. on waste and on the amendment of certain other laws. Dangerous waste is assigned a dangerous property code. These are codes H1 to H13, with properties such as explosivity, liquid flammability, flammability of solids, ability of substances to spontaneously ignite, ability of substances or waste to release on contact with water combustible gases, oxidation ability, thermal permeability of organic peroxides, acute toxicity, infectivity, corrosivity, the ability of substances or waste to release poisonous gases through contact with air or water, chemical toxicity, ecotoxicity and the ability of substances to release other substances after disposal, and leaches that are characterized by some of the above characteristics. The landfill separation mentioned above is used to determine the impact. B.2 Tailings Tailings are also diffused sources of pollution Under Law No. 17/2004 Coll. on landfill charges, as amended; a tailing means a space secured by a dyke system to which predominantly hydraulically transported waste (sludge) is deposited, with the exception of tailings on which sludge produced by mining activity is deposited. The qualitative and quantitative composition of stabilized sludge depends on the quality of the waste material discharged into the disposal system and on the technology used to treat it. As a result, heavy-metal contents in sludge frequently exceed limiting concentrations, are non-degradable, and therefore pose a direct threat to the environment and human health through the soil–plant chain. B.3 Population without a sewer system In the case of populations without a sewer system, flooded septic tanks, and cesspools, which are also included among the diffuse sources of pollution, pose a threat. Septic tanks and cesspools are defined as containers into which wastewater is discharged and which are built where wastewater from the population cannot be discharged into the public sewer system or where such wastewater cannot be treated in a separate small sewage treatment plant.

58

2 Materials and Methods

Due to the population’s connection to the public sewer system, this source of pollution is divided into three categories, according to the percentage of the population without a sewer system in the total population: • 0–40% of the total population is not connected to a public sewer system, • 40–60% of the total population is not connected to a public sewer system, and • 60–100% of the total population is not connected to a public sewer system. B.4 Agriculture Agriculture is a diffuse source of pollution by the application of plant protection products (pesticides) and nitrogen fertilizers, which cause eutrophication of the environment. The total consumption of plant protection products in Slovakia has been rising slightly since 2004. The percentage of arable land from the total flooded area is used to determine the subcategory of this diffuse source of pollution. B.5 Environmental burdens An Environmental Burden (EB) is in accordance with Act No. 384/2009 Coll. defined as pollution caused by human activity which constitutes a serious risk to human health or the environment, groundwater, and soil, with the exception of environmental damage. There is a wide range of areas contaminated by industrial, military, mining, transport, and agricultural activities, which in turn increases soil, rock, and groundwater contamination caused not only in the event of flooding but also by incorrect handling of waste. According to the Environmental Burden Register listed on the web portal of the environmental section, environmental burdens are divided into three categories: • likely environmental burden (register A), • confirmed environmental burden (register B), and • sanitized/reclaimed site (register C). Table 2.10 shows the point classification for the individual sources of pollution to which the weight indicating the importance of the subcategories is assigned. When determining the point classification, inverse order was used, i.e., a value of 5 represents the greatest threat of pollution in the event of flooding. In the same way, the sum of the individual weight of the partial categories, which are normalized, is equal to one. The individual points are determined on the basis of professional judgment. The overall impact (Table 2.11) defines the negative environmental impact and is calculated as the sum of the assigned points by the individual sources of pollution found in the flood area for a given QN (flood probability) multiplied by the respective weight. Table 2.13 is a description of the extent of adverse consequences associated with environmental damage, together with the associated point value for the level of the result. The total point range is determined by all possible combinations of the above categories shown in Table 2.10. The number of combinations is equal to, which is

2.1 Calculation of Potential Flood Damage

59

Table 2.10 Point classification of results for each category of pollution source Type

Source of pollution

Partial source pollution Point classification category

Weight

Enterprises with the presence of hazardous substances

Uncategorized

0.2

Sewage treatment plants

Up to 2,000 EP

Point sources of pollution A1

A2

5

A

0.3

B

0.5 5

2,000–10,000 EP

0.21

10,000–100,000 EP

0.29

Above 100,000 EP A3

Pump stations

0.14

–

0.38 3

1

Diffuse sources of pollution B1

Waste landfills

B2

Tailings

B3

Population without sewer systems

B4

B5

Agriculture

Environmental burdens

Landfills for inert waste 5

0.12

Landfills for non-hazardous waste

0.29

Landfills for hazardous waste

0.59

0–40% of the total population

3

1

4

0.12

40–60% of the total population

0.29

60–100% of the total population

0.59

0–40% of the flooded area

3

0.12

40–60% of the flooded area

0.29

60–100% of the flooded area

0.59

Likely environmental burden

3

0.29

Confirmed environmental burden

0.59

Sanitized/reclaimed site

0.12

broken down using the quartiles method (Zeleˇnáková et al. 2012) into the resulting four point ranges for each level of the result. The value of the result is considered to be the identified threat of environmental pollution during floods from all sources of pollution entering the environmental risk calculation.

60

2 Materials and Methods

Table 2.11 Result category modified by Zvijáková (2013) Level of result Point range

Result

Description of the effect

1

0–6.85

Marginal

Minimal or no degradation of the environment

2

6.86–12.25

Minor

Disturbance of biological communities that is reversible and limited in time and space, or in the number of affected individuals/populations

3

12.26–17.65 Intermediate Disturbance of biological communities that is widespread but reversible or of limited severity

4

17.66–25.03 Major

Extensive biological and physical disruption of entire ecosystems, communities, or entire species that persists over time or is not easily reversible

2.1.3 Loss of Human Lives The proposal for calculating the loss of human life as a result of floods (LOL) is based on the assumption that there is some dependence (correlation) between material damage, the number of people affected by floods, and loss of human life as a result of floods. These losses are mainly due to the failure of information and warning systems or by the lack of discipline and risk-taking by individuals. The number of deaths in a flooded area depends mainly on the number of inhabitants living in the area. The direct cause of death may also include flood factors, such as water flow and elevation, as mentioned in Sect. 1.4. Other territorial factors, such as the collapse of the building due to running water, etc., may also play a role (Ministry of Agriculture of the Czech Republic 2004). In the following subchapters, an inventory of databases and a procedure for determining loss of human life are processed. Data sources and sources for calculating the loss of human lives In order to solve the problem of the negative impacts of the floods on people and/loss of human life, it is necessary to analyze individual historical flood events. Among the available materials, attention is paid especially to floods occurring in recent years (1997–2012) within the Slovak Republic. When selecting a time period, it was taken into account that in the period 1976–1995 there was a flood loss in Slovakia, the occurrence of which was directly related to the reduced precipitation activity (MoE SR 2010a, b, c, d). The choice of the period was also influenced by the availability of documents. Only some major flood situations are described for each year, due to the large number of flood situations in each year. The subchapters contain a brief description of the course of these floods. Information on the number of people killed, on populations affected by floods, and on total damage in euro for each year is shown in Table 2.12 in the subchapter. Some material damage is converted to euro at the current rate. This is the damage from 1997 to 2008, when the official currency in Slovakia was the Slovak crown (SKK).

2.1 Calculation of Potential Flood Damage

61

Table 2.12 List of flood events in the period 1997–2012 in the Slovak Republic Occurrence of floods[Year]

Residents affected by floods [Count]

1997

–

1998

10.850

Deaths [Count]

Total damage [Euros]

1

56.482.274

47

33.208.923

1999

–

1

152.427.737

2000

–

0

40.967.636

2001

–

1

65.081.126

1

50.644.394

2002

5.881

2003

1.844

0

1.457.412

2004

12.434

2

34.913.497

2005

2.411

0

24.045.975

2006

3.927

1

47.898.427

2007

2.277

0

3.637.290

2008

10.742

2

39.616.672

2009

6.998

3

8.417.060

2010

44.380

4

480.851.663

2011

2.029

0

20.100.000

2012

140

Sum

103.913

0 63

2.435.268 1.062.185.353

The information obtained is used to determine and calibrate a relationship for estimating loss of human life. Floods in 1997 Floods in 1997 were extensive, protracted, and affected to a great extent most of the Slovak Republic’s catchment areas. Intense storms hit the territory from 5 to 9 July, and daily rainfall was locally 100–150 mm. Due to the extraordinary precipitation activity, the level of the rivers Danube, Morava, Váh, Hornád, and their tributaries increased. Cognitive flows ranged from Q5 to Q50 (Abbafy 2006). Floods in 1998 In 1998, floods occurred mainly in the eastern part of Slovakia. The first floods occurred when spring water was released in April and May due to heavy rainfall. The next flood activity lasted from 10 July to 31 August and had several phases caused by local storms and heavy rainfall. The largest material damage and major losses of human life occurred in the municipalities of Renˇcišov, Uzovské Pekˇlany, Jarovnice, Dubovina, and Sabinov. Flood waves hit the Malá Svinka, Svinka, Žehrica, and Torysa Rivers and their tributaries. More flooding occurred from 2 October to 2 December. The situation was particularly dramatic for the Uh River and in Lekárovce (MoE SR 2011a, b).

62

2 Materials and Methods

Floods in 1999 After a significant warming in early March, there was a rapid melting of snow, which led to the formation of ice bridges with the flooding of adjacent areas. In June and July, the Slovak Republic was hit by repeated and extreme rainfall, which was accompanied by storm activity. These floods occurred in several phases (Abbafy 2006). Floods in 2000 The flood situation in the spring of 2000 lasted from 1 February to 16 May and hit the Kysuca River in the south, the Nitra River in the southwest, and again, in particular, the eastern part of the country. The accumulation of excessive water reserves of snow contributed greatly to the creation of a historic flood on the Hungarian section of Tisza. The flood situation in Slovakia culminated during the first 10 days of April. On the Tisza, Bodrog, and Latorica, flooding lasted for almost 3 months. Multiple culminations of flood waves occurred on the Lower Tisza and Bodrog and exceeded the 100-year water level (Abbafy 2006). Floods in 2001 In 2001, the first flood activity was from 9 to 16 January, when it was necessary to continuously pump inland water. The discharge of spring water then began dramatically on 5 March with sharp increase of the water level in the Uh River, with a forecast to reach the level at the historical peak. In the second half of July, severe storm activity in northern and northeastern Slovakia caused sharp local increases in the water levels of smaller streams, with subsequent great damage to flows and the property of citizens and municipalities (Abbafy 2006). Floods in 2002 In 2002, floods repeatedly hit the Slovak Republic. In this year, floods occurred in almost all Slovak river basins (the Danube, Váh, Hron, Bodrog, and Hornád River Basins). Due to the extraordinary precipitation in the Danube River Basin in the period before 13 August and the consequent steep rise of water levels in the Upper Danube, an extremely unfavorable situation arose on the Danube and the backwater of the Morava and Váh Rivers (MoE SR 2002a). Floods in 2003 In 2003, several incidents of exceptional flooding occurred in the Slovak Republic during the winter and spring months. Due to sudden warming and intense rain and snowfall in January, water levels rose. The temperature fluctuations during the day and night created conditions for ice movement and the formation of ice barriers in the Moravia, Poprad, and Upper Hornád Rivers. Floods also occurred in the summer months in the territory of the Danube, Váh, Hron, Bodrog, and Hornád Basins (MoE SR 2003a).

2.1 Calculation of Potential Flood Damage

63

Floods in 2004 For the period January–August 2004, flood activity increased again in Slovakia compared to the previous year. A total of 111 days of floods were recorded, with most of the floods occurring in eastern Slovakia. Local floods occurred due to sudden rainfall or storm precipitation, and in July and August, regional floods occurred in eastern Slovakia due to a large frontal rainfall system (MoE SR 2004a). Floods in 2005 In February 2005, spring floods occurred in eastern Slovakia due to snowfall combined with rainfall. In the following months, flooding caused heavy rainfall and local torrential rain, which mainly affected the eastern, southern central, and northwestern Slovakia. The most marked rise in the water levels occurred especially on Nitra, Žitava, Bebrava, Krupinica, and Štiavnica and other smaller streams (MoE SR 2005). Floods in 2006 In early January, heavy rainfall or mixed rainfall occurred with mild warming. Snowfall led to significant increases in water flows and consequently to floods. In the upper sections of the watercourses of central Slovakia, ice phenomena—glaciers also emerged. Floods also occurred in February, March, and April. In the last third of March, rain and intense snowmelt led to a rise in water levels, especially in the watersheds of the rivers Morava, Danube, Váh, Bodrog, Hornád, and Bodva. Increased precipitation in April and May caused a rise in the levels of watercourses of Moravia and Myjava and the internal waters of the Záhorská nížina and Žitný ostrov (MoE SR 2006a). Floods in 2007 In February 2007, heavy rainfall triggered a rise in water levels in western Ukraine, which was also reflected by a rise in the Latorica and Bodrog flows. During the summer, floods occurred mainly due to intense rainfall during a short period of time—torrential rains. Extremely drastic precipitation in the form of rain in the first half of September caused an increase in the water level on the Danube and water from the Kysuca stream and its tributaries, and this caused subsequent flooding of the area (MoE SR 2007a). Floods in 2008 During 2008, floods occurred mainly in January, March, April, and September– December. The most significant floods were recorded during July and August. The most affected were the Topˇla, Ondava, Torysa, Hnilec, and Poprad Rivers in the districts of Bardejov, Svidnik, Stropkov, Prešov, Sabinov, Kežmarok, and Stará ˇ Lubovˇ na. The most critical condition of the monitored area occurred on 23–24 July, when the largest flooding of the affected areas occurred (MoE SR 2008a).

64

2 Materials and Methods

Floods in 2009 Despite the relatively large number of second- and third-degree flood statements, floods in 2009 did not have, as compared to previous years, a particularly serious impact on property. The biggest loss caused by floods in 2009 was the loss of three human lives (MoE SR 2009a). Floods in 2010 The floods in 2010, mainly those in May and June, were unprecedented in their range. Since the beginning of systematically organized and interdepartmental coordinated flood protection, there had not yet been a single year in which over an 8-month period (243 days), 206 days were declared as second or third level of flood activity (85% of the whole period), with floods affecting practically all of Slovakia (Gaˇnová and Zeleˇnáková 2012). From the start of the year to 31 August, flood damage totaling 336,937,688 EUR was recorded and verified in Slovakia. After the extremely wet first half of the year, the floods continued and though they did not reach the hydrological significance of the previous period, they were still influenced by the extraordinary wet first half of the year. The water-saturated river basins responded exceptionally sensitively to the relatively small precipitation activity (MoE SR 2010a, b). Floods in 2011 No flood report for 2011 was available at the time of the survey, so only the consequences of the floods for which information was available were evaluated. Floods in 2012 On 24 February, the warming of several streams caused ice barriers and the rise of water levels from snow melting in early March. Flooding activities have also reached or exceeded at the beginning of April. Floods were declared 30 times from 1 May to 31 August (MoE SR 2012a, b). Summary of flood situations From the aforementioned flood analysis, it can be stated that in the last decade Slovakia has been increasingly affected by varying degrees of flood activity. The increase in precipitation in the territory of the Slovak Republic after a 13-year drought period between 1981 and 1994 had a significant and direct impact on the increased incidence of floods from 1996 onward. In the years 2000–2010, the total precipitation in Slovakia was almost 150 mm higher than in the decade 1981–1990. Analyses of measured hydrological data in the period 1993–2008 show that on the territory of the Slovak Republic the retention of water increased, groundwater resources were recharged, and evaporation also increased (MoE SR 2010a, b, c, d). The consequences of floods point to the fact that society is very vulnerable to flooding. A summary of the consequences of floods on the population and assets of the Slovak Republic for the period 1997–2012 is presented in Table 2.12. As can be seen from Table 2.14, significant floods are recorded in individual flood events, and there are no exceptional cases of loss of life (1997, 1998, 1999,

2.1 Calculation of Potential Flood Damage

65

2001, 2002, 2004, 2006, 2008, 2009, 2010). Out of the 16 evaluated years, no case of death (2000, 2003, 2005, 2007, 2011, 2012) occurred in 7 years. The most significant flooding due to its extent and material damage was that of 2010, with a total estimated damage of 480,851,663 EUR. The most significant flood in terms of the number of casualties is the flood in 1998, resulting in as many as 47 deaths. The table is processed on the basis of the data in the annexes to the flood management reports, which are published on the website of the Ministry of the Environment (SVP 1999; MoE SR 2002b, c; MoE SR 2003b, 2004; MoE SR 2005; MoE SR 2006b, c, d, e, f; MoE SR 2007b, c; MoE SR 2008b, c; MoE SR 2010c, d; MoE SR 2011a, b; MoE SR 2012c). Basic philosophy The process of designing a relationship for the calculation of loss of human life as a result of floods is based on the assumption that there is some dependence (correlation) between material damage, the number of people affected by floods, and the loss of human life as a result of floods. The design and calibration of the relationship are based on the available data on floods that occurred in the Slovak Republic during the period 1997–2012 and are described in the previous subchapter. Verification of the functional dependence of individual factors (the number of affected populations by floods, economic damage, and actual loss of human lives) entering the relationship design is done using a multidimensional correlation analysis. In the final step, a general relationship is proposed for calculating the loss of human lives as a result of floods. Analysis of functional dependencies As mentioned above, the proposal for a relationship for calculating loss of human life (LOL) as a result of floods is based on the assumption that there is some dependence (correlation) between material damage, the number of people affected by floods, and loss of human lives as a result of floods. Verification of the functional dependence of the individual factors entering the relationship design for calculating LOL is performed with multidimensional correlation analysis. Multidimensional correlation analysis is comprised of all statistical methods that simultaneously analyze multiple variables measured on objects of interest. The aim is to understand or identify why and how the variables correlate with each other and how they influence each other (Hair 1998). A correlation coefficient measures the power of statistical dependence between two quantitative variables. Correlation coefficient values are in the range of 0–1. As the correlation coefficient (R) gets closer to 1, the correlation of two variables is higher. Interpretation of the correlation coefficient, however, also depends on the context; for example, a value of 0.8 for verifying a physical law using precision measuring instruments is very low, though it is very high in the social sciences. The values for the correlation coefficient can be classified, e.g., by four degrees of significance (Penja and Dobos 1991) (Table 2.13).

66 Tab 2.13 Degree of significance for the correlation coefficient

2 Materials and Methods Degree of significance

Range (R)

Moderate

0.3 < 0.5

Significant

0.5 < 0.7

High

0.7 < 0.9

Very high

0.9 < 1

Based on the calculated correlation coefficient (R) between LOL and economic damage (0.667) and the dependence between LOL and the number of populations affected by floods (0.783), a high degree of dependence is obvious. The next step is to verify the type of dependency. Verify linear dependence Regression analysis is selected to verify the dependence type. Pair regression analysis examines the linear dependence between two quantitative variables (e.g., the weight and height of a human being). The share of the common variability between the two variables is expressed by the coefficient of determination R2 (R-squared), which is strongly influenced by the extremes (outliers) in both directions. Therefore, in both cases, the 1998 flood event, where an extreme number of deaths (47 victims) was recorded, is excluded. A single extreme can significantly reduce strong dependence but can also produce a strong dependence where there is none. Dependence of economic losses and loss of human lives Figure 2.5 illustrates the dependence of economic damage and loss of human life for the 15 monitored flood events. It is clear from the graph below (Fig. 2.5) that there is a linear dependence (regression line) between the investigated variables (economic damage and LOL). The determination coefficient of R2 is equal to 0.444, which implies that the correlation coefficient R is equal to 0.666, confirming a significant degree of dependence (Table 2.14).

Fig. 2.5 Dependency chart for LOL for 15 flood events

2.1 Calculation of Potential Flood Damage

67

Table 2.14 Comparison of LOL calculated by relation (2.11) with the actual number of victims in the analyzed flood situations Year Real LOL flood (number) occurred

Economic damage (millions of e)

Population affected by floods (number)

LOL calculated Absolute according to error (−) the proposed formula (number)

2002

1

50.6443936

5881

0.697984026

2003

0

1.4574122

1844

0.380866009

2004

2

34.9134967 12434

1.931205078

2005

0

24.0459746

2411

0.307530428

0.30753

2006

1

47.8984266

3927

0.386161924

−0.61384

2007

0

3.63729005

2277

0.438152003

2008

2

39.616672

10742

1.607962661

−0.39204

2009

3

8.41706

6998

1.205478335

−1.79452

2010

4

480.851663 44380

4.014366142

2011

0

20.1

2012

0

2.43526839

Sum

13

Average

1.182

−0.30202 0.380866 −0.06879

0.438152

0.014366

2029

0.272198395

0.272198

140

0.083586714

0.083587

11.32549172 1.029590156

Relative error (%)

-1.67451

12.8808

-0.15223

12.8808

The dependence of people affected by floods and the loss of human life Figure 2.6 shows the dependency of the population affected by floods and the loss of human life for 11 monitored flood events. For the flood events of 1997, 1999– 2001, the numbers of affected populations are not available, and therefore they were excluded from the calculation. It is clear from the above graph that there is a linear (regression line) dependence between the investigated variables (flood-affected population and LOL). The

Fig. 2.6 Dependency chart for LOL for 11 monitored flood events

68

2 Materials and Methods

coefficient of determination R2 is equal to 0.613, which indicates that the correlation coefficient R is equal to 0.783, confirming the high degree of dependence (Table 2.13). Draft relationship for calculating loss of human life Based on the correlation and regression analysis described above, a general relationship in the form of (2.10) is proposed for the calculation of LOL with a multidimensional (in this case a two dimensional) correlation analysis: y = m 1 x1 + m 2 x2 + b

(2.10)

where m1 , m2 , and b are unknowns, and are calculated in Microsoft Excel, which calculates and describes the line that the best matches the specified data using the least squares method. The value y is a function of the independent x values. The m values are the coefficients corresponding to each of the x values and b is a constant. After adding the calculated coefficients into relationship (2.10), the resulting relation for LOL calculation has the form (2.11): L O L = 0, 00017x1 + (−0, 00752)x2 + 0, 078073

(2.11)

where LOL loss of human life, the number of people at risk of flooding, and x1 economic damage (millions of e). x2 Table 2.14 compares the LOL estimated by relation (2.11) with the actual number of victims in the analyzed flood events. It is clear from the table that the proposed relationship (2.11) correlates very well with the actual LOL numbers, which is visible when looking at the absolute error column, where in only one case the difference is greater than 1. Since more data in the LOL column is equal to 0, it is not possible to calculate a relative error for each line separately, as this error is determined only in the sum (in the average). This fact is documented in the last column of the table, with an average relative error not exceeding 13%. Estimation of loss of life due to floods Part of the proposed relationship for calculating loss of human life is also the number of inhabitants vulnerable to floods (x 1 ). All inhabitants living in floodplains of a given flood of QN are counted in the number of vulnerable people. The number of vulnerable people is calculated according to the following formula (2.12): EP = D × FA

(2.12)

2.1 Calculation of Potential Flood Damage

69

Table 2.15 Population density in municipalities and towns (Decree No. 489/2002 Coll.) Description of populated area

Population density H (number of persons/ha)

Rural settlements (community up to 2,000 inhabitants)

10

Centers of villages and rural towns (village, city from 2,000 to 5,000 inhabitants)

20

The outer residential part of a town (municipality, town from 5,000 to 20,000 inhabitants)

30

Cities (from 20,000 to 50,000 inhabitants)

60

Central residential parts of a city (cities over 50,000 inhabitants)

80

Outlying residential area (local areas over 50,000 to 100,000 inhabitants)

90

Central residential area (more than 100,000 inhabitants)

160

The average density of population in the Slovak Republic is 1 person/ha

where EP population endangered by floods (number), D density of the population (number of persons/ha), and FA flooded area (ha). The data for calculating the number of people affected by a flood, especially data on population density, can be obtained from the “Population and Housing Census” conducted by the Statistical Office of the Slovak Republic every 10 years. The last census was carried out in 2011. Another option for obtaining data on the density of occupation in a given area is Table 2.15, which provides information on the density of settlements in towns and cities, and is given in Annex no. 1 to Decree No. 489/2002 Coll. on the Prevention of Major Industrial Accidents. Estimating the number of populations endangered by flooding can be determined more accurately based on flood hazard maps and flood risk maps, and local information for particular flooded parts and streets of towns and municipalities, in addition to the coincidence of a flood area and population density.

2.2 Determining the Level of Flood Risk Based on the identified impact (potential flood damage) for selected flood events, it is possible to determine the level of flood risk. In general, the risk can be expressed as the product of the probability of the occurrence of the adverse event and the consequences of this event according to the formula (1.1), which is mentioned in Sect. 1.1.

70

2 Materials and Methods

Table 2.16 The way of expressing flood risk depending on the outcome Risk

Consequence

Way of expressing risk

Economic risk ER

Damage to property

Economic expression of risk in monetary units—in euro

Environmental risk EnR

Damage to the environment

The extent of environmental risk in dimensionless quantities (point classification)

Social risk SR

Loss of life

Social expression of risk by the expected number of victims per year

risk = pr obabilit y × consequence Risk has the same dimension as the effect of loss or damage, monetary or physical units (number of accidents, deaths, etc.). It follows that the calculation of the average annual risk is still the same, as shown in Table 2.16. In calculating the risk, the distribution function of annual peak flow rates is defined by relation (2.13) (Satrapa et al. 2006):  F(Q x ) =

Qx

f (Q)d Q

(2.13)

0

where F (Qx ) is the value of the distribution function for Qx , that is, the probability that Qx (flow with a particular return period) will not be exceeded in the given year. Thus, the density of the probability of annual maxima is valid (2.14) (Satrapa et al. 2006): f (Q) =

d F(Q) dQ

(2.14)

The probability of overtaking is given by relationship (2.15) (Satrapa et al. 2006): P(Q) = 1 − N (Q)

(2.15)

and therefore relationship (2.16) is valid (Satrapa et al. 2006): d P(Q) = −d F(Q)

(2.16)

The return period of the N-year flow Q is determined using relationship (2.17) (Satrapa et al. 2006): N (Q) = 1 − e− N 1

for N ≥ 5 years, relationship (2.18) is valid:

(2.17)

2.2 Determining the Level of Flood Risk

N (Q) = −

71

1 1 ∼ = ln(1 − P(Q)) P(Q)

(2.18)

The following chapters describe how to report economic, environmental, and social risks as a result of floods.

2.2.1 Economic Risk In the case of property damage, the risk is expressed in economic terms, such as the average annual ERp flood risk reported in e/year. Such risk is calculated according to the formula (2.19), which is based on the probability distribution of annual peak flow rates (Drbal et al. 2008): Q b D E (Q) f (Q)d Q

E Rp =

(2.19)

Qa

where ERp average annual economic flood risk [e/year], DE (Q) value of the economic damage at the flow rate QN resp. damage to property SM [e], Q flow [m3 /year], f (Q) probability density of annual peak flow [-], flow rate at which damage occurs, and Qa flow at which the probability of damage is close to 0. Qb Relation (2.19) can thus be written using (2.15) and (2.18) as (2.20) (Satrapa et al. 2006): Q b E Rp =

Q b D E (Q)d F(Q) = −

Qa

b D E (Q)d P(Q) = −

Qa

D E (N )d

1 N

(2.20)

a

Relationship (2.20) is now easy to solve in numerical terms. Damage DE (Q) bound to the flow rate is appropriate to refer to the return period DE (N). For further deduction, it can be assumed that the height of the damage DE (N) is linearly dependent on the logarithm of the return time at the interval between the values a and b for which damage is known (Fig. 2.7). Damage DE (N) is then calculated according to the following relationship (2.21) (Satrapa et al. 2006; Horský 2008): D E (N ) = DEa + A(ln N − ln a)

(2.21)

72

2 Materials and Methods

Fig. 2.7 Linear dependence of economic damage on the logarithm of the return period in interval (a, b) (arranged according to Horský 2008)

where DE (N) economic damage at flow with the return period N, N, a, b bounded values of the return period interval. A directive of the line between ln a and ln b on the x-axis (gradient of damage), which is calculated according to formula (2.22): A = (DEb − DEa )/(ln b − ln a)

(2.22)

The economic risk for the repetition of time interval (a, b) can be written in the form of (2.23) (Horský 2008): b E Rpi = −

(DEa − A ln a + A ln N )d

1 1 N2

(2.23)

a

and after integration, relation (2.23) takes the form of (2.24) (Horský 2008): 1 1 E Rpi = − [DEa + A(1 + ln b − ln a] + (DEa + A) b a

(2.24)

For the determination of economic flood risk based on flood damage for floods with different return periods, Q5, Q20, Q50, and Q100, the solution can be processed by segmentation according to the following Fig. 2.8. The economic flood risk is set for each interval separately. The total economic flood risk is then given by the sum of the risks at the individual partial intervals of ERpi , according to the determined economic flood damage (to property) according to relationship (2.25) in units of e/year (Drbal et al. 2008): ER =



E Rpi

(2.25)

2.2 Determining the Level of Flood Risk

73

Fig. 2.8 Determination of economic flood risk based on knowledge of flood damage for different flows (arranged according to Satrapa et al. 2006)

The individual intervals are chosen according to the calculated damage, with the beginning (first interval) being chosen for the return period at which the damage begins to occur, and the last interval can be selected from Qext (extreme) extrapolation at a constant value to at least N = 1000 or 10,000), where the likelihood of occurrence is minimal and the share of the total risk is almost unlikely. Since the value of the damage is not expressed for flows larger than Qext (usually for 100, 200 years), it can be reasonably assumed that the damage will certainly be less than that for Qext , so extrapolation can be used with a constant value for floods with a higher return period. The real risk would be greater, but this negligible error will not be reflected in the calculations for which the described methods are determined (usually, flood protection projects whose design protection rate will not be higher than Qext ) (Horský 2008). The present value of the risk can be expressed through a discount rate. On January 19, 2008, the European Commission published a notice in the Official Journal on the revision of the method for setting reference and discount rates (OJ C 14 2008). In line with this method, the Commission set the basic rate for the calculation of the reference and discount rates in the Slovak Republic of 0.53% from January 1, 2014. Depending on the use of the reference rate, the relevant margins should be added to this basic rate, as set out in that notice. In the case of a discount rate, this means an increase of 100 base points = 1 percentage point (MoF SR 2013). The discount rate represents the rate of return required by the investor for the investment in a given risk range, and for the Slovak Republic this is set at 1.53% (base rate 0.53% + 1% = 100 basis points). The present value of the risk (capitalized risk) is then based on relationship (2.26) defined for the Eurydice calculation (Horský 2008): E Rk =

ER DS

where ERk current flood risk (capitalized risk) [e],

(2.26)

74

ER DS

2 Materials and Methods

economic flood risk per year [e/year],and annual discount rate in decimal [-].

2.2.2 The Environmental Risk of Floods The environmental risk due to floods is determined on the basis of the calculated environmental impact of floods with different return periods, Q5% , Q20% , Q50% , and Q100% . The numerical expression of the relation for calculating the average annual rate of environmental risk [-] for each return period is as follows (2.27):  En Rpi = a

b

 n    D j + D j+1  P j − P j−1 D(Q)d P(Q) ≈ 2 j=1

(2.27)

where D the level of the result determined by Table 2.13. The probability of overtaking is given by relationship (2.15). We choose the individual increments as well as the calculation of economic risk (Sect. 2.2.1). The overall environmental risk [-] is then given by the sum of the risks at the individual EnRpi intervals, as determined by (2.28): En R =



En Rpi

(2.28)

This level of environmental risk caused by floods allows us to assess the need for flood control measures also in view of environmental damage and can be the basis for assessing the effectiveness of flood protection measures in this respect.

2.2.3 Social Expression of Risk In the case of loss of life, risk is expressed in social terms, as the average annual number of deaths due to floods. When calculating the average annual social risk, it is a probability of hazard and the adverse impacts of floods on people’s lives or loss of human life. The risk can therefore be quantified by the estimated average annual number of flood-induced casualties. Based on the impact on human life, risk is divided into individual and social risk. Individual risk is defined as the annual probability that an unprotected person on ˇ the affected site is sacrificed by the effect of the hazard (Ríha et al. 2005; Jonkman et al. 2003) (2.29): I R = P f Pd/ f

(2.29)

2.2 Determining the Level of Flood Risk

75

Fig. 2.9 Difference between individual and social risk (arranged according to Jonkman et al. 2003)

where IR the individual risk, Pf the probability of an undesired event, and Pd/f likelihood of death of an individual in the case of an undesired event. If the focus is on a certain territory and on the endangered population that is in this area, then we are talking about social risk. It can be expressed as the relationship between frequency of occurrence and the number of people who are exposed to the hazard and may suffer injury or death. Social risk describes the integrated number ˇ of deaths for the entire defined area (Ríha et al. 2005). The difference between individual and social risk is explained in Fig. 2.9. Both situations have the same level of individual risk (IRA, IRB). Because in Situation B there is a higher density of persons in the hazard zone, situation B has higher social risk (Jonkman et al. 2003). From a mathematical point of view, the average annual social risk of loss in human life can be written in different ways (Jonkman 2007). The easiest way is to use the mean value of the expected annual E(LOL) according to formula (2.30): ∞ S Rp = E(L O L) =

L O Ld P(Q)

(2.30)

0

where SRp is the average annual social risk, which is expressed by the number of human victims, respectively, the loss of human lives per year calculated using relation (2.11) and P is the probability of the relationship overruns (2.15). Formula (2.31) proposed by Vrijling et al. (1995) is used to calculate the mean annual social risk for each interval of return periods.

76

2 Materials and Methods

S Rpi = E(L O L)i + kσ (L O L)i

(2.31)

where SRpi E(LOL)i σ k

average annual social risk (persons/year), the expected annual number of victims (persons/year), standard deviation (-), and the coefficient of aversion (-) or risk aversion (neutral attitude or risk).

Social risk is quantified using relationship (2.31) as the expected annual number of victims’ E(LOL) with the standard deviation σ (LOL), multiplied by the coefficient of risk aversion, which usually takes a value from 1 to 3 (Vrijling et al. 1995). If k = 1, the risk aversion is neutral; for values 2 and 3 the risk aversion is taken into account (Jonkman 2007). Authors from the Netherlands (Vrijling et al. 1998) report a value of k = 3, while in the Czech Republic the coefficient of social aversion to flooding was set at k = 2 (Drbal et al. 2011). This societal risk is sometimes referred ˇ to as “risk aversion” (Vrijling et al. 1998; Ríha et al. 2005). The numerical expression of the relationship for the calculation of the expected annual number of victims E(LOL) and for each interval of repetition periods is as follows (2.32) (Brázdová 2012): b E(L O L)i =

L O L(Q)d P(Q) ≈ a

 n   L O L j + L O L j+1 (P j − P j−1 ) 2 j=1 (2.32)

The indicative deviation σ (LOL) is calculated according to relationship (2.33) (Brázdová 2012):

b (L O L − E(L O L))2 d P(Q) ≈ σ (L O L)i = a n (L O L j −E(L O L))2 +(L O L j+1 −E(L O L))2 (P j − P j−1 ) 2

(2.32)

j=1

where LOL j is the estimated number of victims QN is the flow calculated using relation (2.11), and P is the probability of the overflow given by relationship (2.15). We choose the individual increments as well as the calculation of economic risk (Sect 2.2.1). The overall social risk is then given by the sum of the risks at the individual SRpi intervals according to the determined loss of human life, expressed in units of person per year (2.33):

2.2 Determining the Level of Flood Risk

SR =

77



S Rpi

(2.33)

The established degree of social risk enables us to assess the need for flood protection measures also in terms of loss of human life.

2.3 Evaluation of the Effectiveness of Flood Protection Measures The following chapters describe ways to evaluate the effectiveness of flood protection. Part of this chapter is a description of flood protection measures. The assessment of the effectiveness of flood protection measures (FPM) is done in three ways. In the case of economic risk, which is expressed in monetary form, the effectiveness of FPMs is assessed from an economic point of view. Taking into account the effectiveness of FPMs with regard to environmental protection, account is taken of the reduction in environmental risk, expressed as a percentage. In the case of FPM’s effectiveness with regard to the protection of human life, effectiveness is expressed through an acceptable level of social risk. The different ways of expressing effectiveness are described below.

2.3.1 Economic Efficiency Economic efficiency (E) represents the ratio of the achieved benefit (B) to the cost of the total investment (I) (Trávnik et al. 2003). A procedure to define and compare the benefits and costs of an FPM, that is, its cost-effectiveness, is called a Cost–Benefit Analysis (CBA) (also cost and benefit analysis or cost analysis). This is a process that can help in the decision-making process (but it is not the decision-making process itself). In order to evaluate the economic efficiency of an FPM, it is possible to use standard parameters (relative efficiency, absolute efficiency, and payback time) containing cost and utility analysis (Horský 2008; Satrapa et al. 2011). • Relative efficiency (RE) reflects the relative economic efficiency of an investment or flood protection measures. It is understood as a quantity expressing the ratio of output and input, where in the numerator the current capitalized risk is reduced by the capitalized risk after the eventual realization of the FPM project and in the denominator is the costs necessary for carrying out the FPM project. The denominator essentially expresses the necessary reduction in capitalized risk by implementing measures. To calculate the relative efficiency of FPM, formula (2.34) is used:

78

2 Materials and Methods

RE =

E Rk ( pr eimplementation F P M) − E Rk ( postimplementation F P M) C (2.34)

where RE ERk (pre-implementation of FPM) ERk (post-implementation of FPM) C

relative efficiency [-], the current value of the economic flood risk (capitalized risk) before the FPM realization [e], the current value of the economic flood risk (capitalized risk) after realization of the FPM [e], and total cost of FPM implementation [e].

The higher value of the parameter reflects a higher appreciation of the investment in the preventive measure. The measure will be effective if the parameter is greater than 1 and, on the other hand, ineffective if the parameter is less than 1. • Absolute efficiency (AE) is the parameter expressing the effectiveness of the investment or measures in absolute economic units. Its value is calculated from relationship (2.35):   AE = E Rk ( pr eimplementation F P M) − C + E Rk ( postimplementation F P M)

(2.35) The meaning of the symbols is identical to the description of the symbols in calculating relative efficiency. Absolute effectiveness expresses the financial effect of the proposed FPM in the long run in financial units [e]. A higher (positive) value of this parameter means higher appreciation of the investment in the FPM project. In the case of negative values, this is an inefficient investment, or there is an economic disadvantage in implementing such a measure. • The payback period (PP) is used to estimate the economic efficiency of the FPMs through the payback period based on relationship (2.36):

PP =

C E R p ( pr eimplementation F P M) − E R p ( postimplementation F P M) (2.36)

where PP C ERp ERp

payback period [years], total cost of FPM [e], average annual economic risk before FPM implementation [e/year], and average annual economic risk after FPM realization [e/year].

2.3 Evaluation of the Effectiveness of Flood Protection Measures

79

Comparing the payback time of individual FPMs with limit values according to domestic and foreign experience provides another tool for objectively assessing FPMs in an international context.

2.3.2 Environmental Risk Acceptability Expression of the economic efficiency of FPMs in terms of environmental damage is not possible, as the environmental risk due to floods is a dimensionless variable. Therefore, the environmental effectiveness of an FPM is determined as a measure of environmental risk reduction (MR), calculated as a percentage using relationship (2.37):   En R( postimplementation F P M) M R = 100 − × 100 En R( pr eimplementation F P M)

(2.37)

where EnR total environmental risk [-]. A higher value of this parameter (higher percentage) means a higher FPM efficiency with respect to environmental protection.

2.3.3 Socially Acceptable Level of Social Risk The acceptability of risk depends mainly on social and political aspects, so the limits of risk acceptance vary depending on the country and the type of activity. Determining these limits is an important role in assessing and managing risk, as these limits indicate whether the risk is to be reduced to an acceptable level (Vrijling et al. 1998). It is important to note that there is a chance that the risk is acceptable at a reasonable level, and therefore no reduction is necessary. Explaining economic efficiency with social risk is very complicated, as the expression of human life in monetary terms is not practically possible. Therefore, the acceptability limit is set for social risk, which must be respected in the design of flood protection measures with a view to reducing harm to human life. Acceptable social risk can be expressed in the same way as flood risk: by means of the average annual number of deaths in a given locality or by a comparison expressed in the F-N diagram, which expresses the dependence between the probability of the occurrence (F) and the consequences expressed by the number of victims (N) (Vrijling et al. 1998). The level of socially acceptable risk should be based on a model of social risk perception. In determining the acceptable level of social risk, the standard employed by Vrijling et al. (1995) is used in the presented research.

80

2 Materials and Methods

Table 2.17 Political factors β depending on degree of volition (Brázdová 2012)

β

Degree of volition

100

Totally voluntary

10

Voluntary

1.0

Neutral

0.1

Involuntary

0.01

Totally involuntary

The level of acceptable social risk in this case is determined at the national level and is expressed in the following relation (2.38): S Raccept. = β M

(2.38)

where β is a political factor based on the volunteer’s ability (Table 2.17) and M is the average acceptable number of victims of floods per year. It should be noted that the value β must be chosen for each threat group that differs in its relation to the threat. For example, rescuers and endangered residents perceive and take the risk in a different way. While rescuers take the risk of flood damage on a voluntary basis, vulnerable residents in vulnerable areas are at risk of exposure involuntarily. Table 2.17 shows the values of the political factor β in terms of volition. The M value is country specific. Authors Vrijling et al. (1995) report an average acceptable number of casualties for floods per year of 100. This parameter includes indicators such as the occurrence of a threat to the country, the state of the rescue system, the size and density of the population, etc. In the Slovak Republic, this value is defined for the legislative floods on a national scale. The basis for the design of this parameter is the actual number of victims resulting from the flood analysis in the period 1997–2012. The average acceptable number of victims per year is calculated according to the following relationship (2.39) taken from Brázdová (2012): 16

M=

L O L actual years

i=1

(2.39)

where M average acceptable number of victims per year (persons/year), LOL actual number of actual victims in individual years (persons), and years sum of analyzed years (16). On the basis of relationship (51), the value of the average acceptable number of victims per year for M ~ 4 persons/year is derived for floods in the Slovak Republic.

2.3 Evaluation of the Effectiveness of Flood Protection Measures

81

Table 2.18 Calculation of the value of acceptable social risk (persons/year) for floods in the Slovak Republic

M (persons/year)

LOL actual (persons)

Number of analyzed years

63

16

(63/16) 3.9375

Political factor β (-)

0.01

β*M

0.01 * 3.9375

LOL actual (persons/year)

0.03975

In determining the acceptable level of social risk, it is assumed that all victims are flooded involuntarily, so the political factor β gets a value of 0.01. The final value of the acceptable level of social risk in the Slovak Republic for floods is LOL actual = 0.03975 (persons/year). Calculation of this value is shown in Table 2.18. The resulting value (SRaccept. ) expresses the acceptable value of social risk or the acceptable annual loss of human lives during one flood situation within the Slovak Republic. When comparing the acceptable risk (SRaccept. ) with the total annual social risk (SR), the procedure proposed by Vrijling et al. (1995) suggests that total risk TR must meet the following condition (2.40): T R < βM

(2.40)

To compare the acceptable social risk (SRaccept. ) with the total annual social risk (SR) in the Slovak Republic, the following relationship is assumed (2.41): S R < S Raccept. S Rpi < β M [E(L O L) + kσ (L O L)] < 0.03975 (persons/year)

(2.41)

By comparing the acceptable risk with the total annual social risk, the existing status of the evaluated site is determined, i.e., whether the site is assessed at acceptable levels of annual social risk, that is, the value of social risk is less than 0.03975 per year. If the value of social risk falls to unacceptable limits, it is also necessary to propose FPMs that would reduce the social risk. Subsequent to FPM design, a recomparison of the SRaccept and SR values is required to find out whether the annual societal risk will be reduced to an acceptable level and whether the FPM proposal for the protection of human life is effective.

82

2 Materials and Methods

2.3.4 Flood Protection Measures The final phase of flood risk management is the selection of appropriate and effective flood protection measures (FPMs) depending on the risk. The selection of a measure for a particular site, however, also depends on the type of territory, the natural conditions, the requirements for flood protection, the financial possibilities, and the ownership of the land. The proposed FPM is always a complex activity based on a detailed analysis of the territory. However, it should be noted that the consequences of floods can only be alleviated by means of a comprehensive system of flood control measures. Due to the time of implementation, Law No. 7/2010 Coll. divides FPM into four categories: preparatory, carried out in time of flood danger, carried out during a flood, and done after a flood. Preparatory measures are the gateway to a comprehensive solution to this issue, so the focus in this chapter is mainly on these measures. Due to their nature, the measures taken before a flood are divided into • Organizational—preparation of flood plans, flood inspections, organizational and technical preparation, flood protection, preparation of the information system, and training of flood workers. • Technical—construction of water management facilities for a certain degree of protection—water stream regulation, construction of mobile walls, protective walls and protective dams, drainage channels, and pumping stations. • Environmental (FPM close to nature)—grass belts, wetlands, depressions, small water ponds, and revitalization of floodplain areas. Among the most common, and in the sense of Law No. 7/2010 Coll. also mandatory preparatory organizational measures, are flood relief plans that are developed following flood protection plans. The content of flood planning is regulated by Decree No. 261/2010 Coll., which lays down the details on the content of the plans and the procedure for their approval. The most effective measures are, in addition to rigorously drawn up flood plans, technical and environmental measures that reduce flooding or peak flow rates and increase the flow capacity of a riverbed. Based on their functionality, these measures can be divided into two groups: • measures that reduce the maximum flood flow (polders, flow adjustment, reservoirs, barriers, and delineation of flood wave transformation); and • measures to protect areas from flooding by internal waters (inland water treatment facilities—construction and maintenance). Prior to the selection of FPM, it is necessary to know not only the financial possibilities, but also the basic characteristics of the measures, the environmental impacts of their implementation, etc. Modern flood protection measures should, in addition to their technical functionality, also fulfill esthetic, landscaping, or recreational functions. In the following section, the abovementioned FPMs are briefly described.

2.3 Evaluation of the Effectiveness of Flood Protection Measures

83

Fig. 2.10 Polder Oreské

Dry polder The main function of a dry polder is to regulate runoff in order to reduce the maximum flood flow moving from the higher part of the basin to a size that should not flow out of a channel in the urban area under the polder (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005). The dry polder itself (Fig. 2.10) is a naturally or artificially bound space adjacent to the flow which, upon filling with water during a flood, has a retention function, thus reducing the flood flow. After the flood wave transition, the polder is completely emptied (dry). Cihláˇr et al. (2005), Švecová and Zeleˇnáková (2005), STN 75 0120. A key element of our proposed polders is a functional construction that forms part of a dyke. This object has an outflow in the dyke, and a safety barrier (Fig. 2.11) is part of the functional barrier, which safely discharges those flows that are larger than the capacity of the outlet of the dyke (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005). The basic conditions of realization are (Cihláˇr et al. 2005) as follows: • appropriate geomorphological conditions in the area of implementation; • resolved management in floodplain, including land ownership; • the possibility of obtaining the necessary ground materials at an economically acceptable distance; and • buildings for housing, production sites, or landfills that could endanger water quality may not be located in the floodplain area. The primary effect of this measure is the guarantee of peak flow reduction. Water retention in the country is considered a secondary effect. In places with a congested

84

2 Materials and Methods

Fig. 2.11 Polder Myjava

groundwater level, the dry polder function may appear to be positive in view of the increase in groundwater level. The change in conditions of intensive management, the possible breaking of the polder dyke barrier, or some other failure in the waterworks and the spillage of the retained water into the adjacent plots (Cihláˇr et al. 2005) is considered to be a negative impact. Reservoirs The main purpose of a reservoir is the accumulation (capture and retention) of water, which mediates and compensates for inequalities in the inflow into the reservoir and the removal of water from it. Thus, a reservoir is a space created by a flooded structure on a watercourse using a natural or artificial recess or depression in the earth’s surface, or by enclosing part of an area intended for water accumulation and drainage control (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005) (Fig. 2.12). In principle, water storage structures are divided according to (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005) • • • •

origin (natural lakes or artificial reservoirs); location and relationship to the water source (run, unchecked, and sideways); the purpose(s) to be served (stock, water, and multipurpose); and cycle of regulation (multiannual, annual, seasonal, and non-regular cycle).

2.3 Evaluation of the Effectiveness of Flood Protection Measures

85

Fig. 2.12 The Ružín I. Reservoir (www.skcold.sk)

A reservoir is an important element that can more or less significantly affect the natural flow regime, and its design and construction are among the most demanding, the most complex, and also the most expensive works of water engineering (Švecová and Zeleˇnáková 2005). The basic conditions of realization are (Cihláˇr et al. 2005) as follows: • selecting a suitable location that depends on the shape of the valley, the geological conditions, and the floodplain area and • resolving all the impacts and conflicts that arise from the reservoir construction. The primary effect is the reduction of peak flow and the more gradual distribution of a flood wave. If the reservoir is not used for drinking water, the structure allows recreational and fishing use, which can be considered a secondary effect. The unfavorable effect of the construction of the reservoir is a radical interference with the natural environment, often requiring the partial or complete resettlement of people in the floodplain area and the danger to the population resulting from the potential breach of the dam (Cihláˇr et al. 2005). Regulated Streams Stream regulation (Fig. 2.13) involves a set of water, forest, agricultural, and other conditions and river basin management measures designed to create favorable conditions for the discharge of water by streams and to remove the consequences of their detrimental effects. A necessary condition for the design and implementation of the watercourse treatment is the evaluation of the current state, especially the natural components of the area used and requirements for the function of the water flow (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005; STN 75 0120).

86

2 Materials and Methods

Fig. 2.13 Regulated stream in the village of Vydrník, (Zeleˇnáková et al. 2012)

Common flow management includes flow guidance (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005): • removing sharp bays that prevent water runoff and allow ice formation; • concentration of water from branched channels into one stream; • removing islands and casual obstacles that are not conducive to the smooth flow of water; • creating a longitudinal slope of flow that corresponds as much as possible to the steady state of the bed; and • creation of a profile for the channel of such dimensions and shapes as to avoid damaging the previous flows with such reinforcements, which would prevent the sinking and flushing of the banks. The basic conditions of realization are (Cihláˇr et al. 2005) as follows: • appropriate spatial and slope conditions; • the reality of investment-driven solutions (e.g., modification of infrastructure networks, roads, railways, and residential areas); and • acquisition of land ownership rights. The primary effect is to increase the flood protection of the site involved. Interference with land and land ownership is a secondary effect of streamlining, requiring rigorous planning with an emphasis on the environment and its diversity (Cihláˇr et al. 2005).

2.3 Evaluation of the Effectiveness of Flood Protection Measures

87

Fig. 2.14 The Ondava dyke

Protective dykes Protective dykes (Fig. 2.14) are structures defining a space for flood flow management on streams and at the same time fulfilling the function of a flood line element in a flood protection system. A protective dyke is a structure for the protection of land and buildings from flooding in high water bodies (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005; STN 75 0120). Dykes are built where the floodplain is large and flat, if it cannot otherwise reduce the flood waves, thus preventing flooding. They are artificially built walls or embankments alongside channels or ditches usually filled with soil or stones to protect against floods (Cihláˇr et al. 2005; Švecová and Zeleˇnáková 2005). The basic conditions of realization are (Cihláˇr et al. 2005) as follows: • • • •

appropriate spatial and geological conditions; obtaining suitable building material at an economically acceptable distance; minimizing flood damage; and obtaining rights to the land needed for implementation.

The primary effect is to increase the flood protection of the site involved. We can consider the more efficient use of the protected area as a secondary effect (Cihláˇr et al. 2005). A flood protection strategy must address the entire area of the protected river basin in a comprehensive manner and promote the coordinated development and management of activities that concern not only the hydrological cycle, but also other environmental, local government, legislation, and property rights. It is necessary to

88

2 Materials and Methods

create a flood protection system that uses existing knowledge and ensures long-term support from the community (Simonová 2012).

References Abbafy D (2006) Floods in the Slovak Republic in 1996–2005 and their consequences (in Slovak). Vodohospodársky spravodajca XLIX:3–4 Act No. 163/2001 Coll. on chemical substances and chemical preparations (in Slovak) Act No. 17/2004 Coll. on Waste Deposit Fees as amended. (in Slovak) Act No. 364/2004 Coll. on Waters and on Amendment to Act of the Slovak National Council no. 372/1990 Coll. on offenses as amended (Water Act). (in Slovak) Act No. 409/2006 Coll. on Waste and on amendments to certain acts. (in Slovak) Act No. 405/2008 Amending and supplementing Act no. 163/2001 Coll. on chemical substances and chemical preparations, as amended, and on amendments to certain acts. (in Slovak) Act No. 384/2009 Coll. amending Act no. 364/2004 Coll. on Waters and on Amendment to Act of the Slovak National Council no. 372/1990 Coll. on offenses, as amended (Water Act), as amended, and amending and supplementing Act no. 569/2007 Coll. on Geological Works (Geological Act) as amended by Act no. 515/2008 Coll. (in Slovak) Act No. 7/2010 On protection against floods. (in Slovak) Act of the National Council of the Slovak Republic. no. 359/2007 Coll. on the prevention and remedy of environmental damage and on amendments to certain acts. (in Slovak) Act of the National Council of the Slovak Republic. no. 543/2002 Coll. on nature and landscape protection. (in Slovak) Act No. Amending and supplementing Act No. 368/2013 Coll. 135/1961 Coll. on Roads (Road Act), as amended, and on amendments and supplements to certain acts. (in Slovak) Brázdová M (2012) Estimation of loss of human life during flood (in Czech). Dissertation work, FAST VUT v Brnˇe, Brno, p 166 Cihláˇr J, Smrˇcka F, Hála R, Garkischová A, Fridrich J, Nˇemec L (2005) Catalog of measures-Annex D. Datasheets (in Czech). Water Management Development and Construction, Ltd., Prague Decree of the Ministry of the Environment of the Slovak Republic No. 489/2002 Implementing some provisions of the Act on Prevention of Major Industrial Accidents and on Amendments to Certain Acts. (in Slovak) Decree of the Ministry of the Environment of the Slovak Republic No.261/2010 Laying down details on the content of flood plans and the procedure for their approval. (in Slovak) Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks. (in Slovak) Drbal K et al (2011) Risk maps resulting from flood hazard in the Czech Republic (in Czech). Final Report. Brno Drbal K et al (2008) Methodology of flood risk and damage assessment in flood plains (in Czech). Water Research Institute T.G. Masaryk, Brno, p 72 Gaˇnová L, Zeleˇnáková M (2012) Assessment of flood damages in 2010 in eastern Slovakia (in Slovak). Životné prostredie 46(2): 98–102. ISSN 0044–4863 Hair JF (1998) Multivariate data analysis (5th ed). Prentice-Hall Int, London atd Horský M (2008) Methods of evaluation of potential flood damage and their application by means of GIS (in Czech). Dissertation thesis. Prague, p 124 Jonkman SN (2007) Loss of life estimation in flood risk assessment. Theory and applications. Disertation. Delft University of Technology, p 360 Jonkman SN, Van Gelder P, Vrijling JK (2003) An overview of quantitative risk measures for loss of life and economic damage. J Hazard Mater 99(1):1–30

References

89

MoE SR (Ministry of Environment of the Slovak Republic) (2002a) Report on floods on watercourses in the Slovak Republic in 2002. http://www.minzp.sk/files/sekcia-vod/povodne-20022012-informacie/sprava-o-povodniach-2002.pdf (in Slovak) MoE SR (2002b) Summary of the consequences of the 2002 floods. Annex no. 1. http://www.minzp.sk/files/sekcia-vod/povodne-2002–2012-informacie/nasledky-sposobenepovodnami-2002.pdf (in Slovak) MoE SR (2002c) Assessment of damage caused by floods in 2002 to property of inhabitants, municipalities, regional and district authorities. Annex no. 5. http://www.minzp.sk/files/sekcia-vod/pov odne-2002–2012-informacie/vyhodnotenie-skor-majetku-obyvatelov-obci-ku-a-ou2002.pdf (in Slovak) MoE SR (2003a) Report on floods on watercourses in the Slovak Republic in 2003. http://www.minzp.sk/files/sekcia-vod/povodne-2002–2012-informacie/sprava-o-povodn iach-2003.pdf (in Slovak) MoE SR (2003b) Summary of the consequences of the 2003 floods. Annex no. 1 http://www.minzp.sk/files/sekcia-vod/povodne-2002–2012-informacie/prehlad-nasledkov-pov odni-2003.pdf (in Slovak) MoE SR (2004a) Summary of the consequences of the 2004 floods. http://www.minzp.sk/files/ sekcia-vod/povodne-2002-2012-informacie/sprava-o-povodniach-v-sr-v-obdobi-januar-august2004.pdf (in Slovak) MoE SR (2004b) Report on floods on watercourses in the Slovak Republic in 2004. Príloha cˇ . 1. http://www.minzp.sk/files/sekcia-vod/povodne-2002–2012-informacie/prehlad-nasledkovpovodni-januar-august-2004.pdf (in Slovak) MoE SR (2005) Report on floods on watercourses in the Slovak Republic in 2005. http://www. minzp.sk/files/sekcia-vod/povodne-2002–2012-informacie/sprava-o-povodniach-v-sr-v-obdobioktober-december-2005.pdf (in Slovak) MoE SR (2006a) Report on the course and consequences of floods and on the flood protection measures implemented for the period January-April 2006. http://www.minzp.sk/files/sekciavod/povodne-2002-2012-informacie/sprava-o-povodniach-v-sr-v-obdobi-januar-april-2006.pdf (in Slovak) MoE SR (2006b) Overview of the consequences of the floods in January-April 2006. Annex 2. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/nasledky-povodni-i.l2006.pdf (in Slovak) MoE SR (2006c) Overview of the consequences of the floods in May-December 2006. Annex 2. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/nasledky-pov odni-ii.2006.pdf (in Slovak) MoE SR (2006d) Quantification of the damage caused by the floods in the period January-April 2006. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/zhr nutie-skod-i-povodne-2006.pdf (in Slovak) MoE SR (2006e) Quantification of the damage caused by the floods in May-December 2006. Annex 9. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/zhrnutie-skodii-povodne-2006.pdf (in Slovak) MoE SR (2006f) Additional assessment of the damage caused by floods to property within the territorial competence of public authorities in 2006. Annex B3. http://www.minzp.sk/files/sekcia-vod/ povodne-2002-2012-informacie/dodatoicne-skody-na-majetku-povodne-2007.pdf (in Slovak) MoE SR (2007a) Report on floods on watercourses in the Slovak Republic in 2007. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/sprava-o-priebehua-nasledkoch-povodni-v-sr-v-roku-2007.pdf (in Slovak) MoE SR (2007b) Overview of the consequences of the floods in 2007. Annex A2. http://www.minzp. sk/files/sekcia-vod/povodne-2002-2012-informacie/nasledky-povodni-2007.pdf (in Slovak) MoE SR (2007c) Assessment of flood damage to property within the territorial competence of public authorities in 2007. Annex A8. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-inf ormacie/naklady-na-majetku-povodne-2007.pdf (in Slovak)

90

2 Materials and Methods

MoE SR (2008a) Report on floods on watercourses in the Slovak Republic in 2008. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/sprava-o-priebehua-nasledkoch-povodni-v-sr-v-roku-2008.pdf (in Slovak) MoE SR (2008b) Overview of the effects of the floods in 2008. Annex A2. http://www.minzp. sk/files/sekcia-vod/povodne-2002-2012-informacie/nasledky-povodni-v-sr-v-roku-2008.pdf (in Slovak) MoE SR (2008c) Assessment of flood damage to property within the territorial jurisdiction of public authorities during the 2008 floods. Annex A8. http://www.minzp.sk/files/sekcia-vod/pov odne-2002-2012-informacie/vyhodnotenie-skod-na-majetku-povodne-2008.pdf (in Slovak) MoE SR (2009a) Report on floods on watercourses in the Slovak Republic in 2009. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/sprava-o-priebehua-nasledkoch-povodni-v-sr-v-roku-2009.pdf (in Slovak) MoE SR (2009b) Bodva River Basin Management Plan. http://www.vuvh.sk/download/RSV/07_ PMP_Bodva/01_Plan%20manazmentu%20ciastkoveho%20povodia%20Bodva/PMCP_Bodva. pdf (in Slovak) MoE SR (2010a) Report on the course and consequences of floods in the Slovak Republic from 1 January to 31 August 2010. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-inf ormacie/sprava-o-priebehu-a-nasledkoch-povodni-v-sr-v-obdobi-januar-az-august-2010.pdf (in Slovak) MoE SR (2010b) Report on the course and consequences of floods in the Slovak Republic from 1 September to 31 December 2010. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-inf ormacie/sprava-o-priebehu-nasledkoch-povodni-v-sr-v-obdobi-september-az-december-2010. pdf (in Slovak) MoE SR (2010c) Annex to the Report on the course and consequences of floods in the territory of the Slovak Republic from 1 September to 31 December 2010 (table part). http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/suhrnne-tab ulky-povodne-v-sr-v-obdobi-september-az-december-2010.pdf (in Slovak) MoE SR (2010d) Annex to the Report on the course and consequences of floods in the territory of the Slovak Republic from 1 January to 31 August 2010 (table part). http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/nasledky-povodniv-sr-v-obdobi-januar-az-august-2010.pdf (in Slovak) MoE SR (2011a) Annex to the Report on the course and consequences of floods in the territory of the Slovak Republic from 1 January to 31 August 2011 (table part). http://www.minzp.sk/ files/sekcia-vod/povodne-2002-2012-informacie/priloha-k-sprave-o-priebehu-a-nasledkoch-pov odni-v-sr-v-obdobi-januar-az-august-2011.pdf (in Slovak) MoE SR (2011b) Annex to the Report on the course and consequences of floods in the territory of the Slovak Republic from 1 September to 31 December 2011 (table part). http://www.minzp.sk/ files/sekcia-vod/povodne-2002-2012-informacie/priloha-k-sprave-o-priebehu-a-nasledkoch-pov odni-v-sr-v-obdobi-september-az-december-2011.pdf (in Slovak) MoE SR (2012a) Report on the course and consequences of floods in the Slovak Republic from 1 January to 30 April 2012. http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/ sprava-o-priebehu-a-nasledkoch-povodni-v-sr-v-obdobi-januar-az-april-2012.pdf (in Slovak) MoE SR (2012b) Report on the course and consequences of floods in the Slovak Republic in the period from 1 May to 31 August 2012. http://www.minzp.sk/files/sekcia-vod/povodne-20022012-informacie/sprava-o-priebehu-a-nasledkoch-povodni-v-sr-v-obdobi-maj-az-august-2012. pdf (in Slovak) MoE SR (2012c) Annex to the Report on the course and consequences of floods in the territory of the Slovak Republic from 1 January to 30 April 2012 (table part). http://www.minzp.sk/files/sekcia-vod/povodne-2002-2012-informacie/suhrnne-info-o-pri ebehu-a-nasledkoch-povodni-2012.pdf (in Slovak) MoF SR (Ministry of Finance of the Slovak Republic) (2013) Reference rate, discount rate and interest rates for State aid recovery. http://www.finance.gov.sk/Default.aspx?CatID=5415 (in Slovak)

References

91

ˇ (Ministry of Agriculture of the Czech Republic) (2004). Strengthening of risk analysis and MZe CR determination of active zones in Czech water management http://eagri.cz/public/web/file/16369/ posileni_rizikove_analyzy.pdf (in Czech) Official Journal C 014, 19/01/2008, Communication from the Commission on the revision of the method for setting the reference and discount rates, p 6–9. http://eur-lex.europa.eu/LexUriServ/ LexUriServ.do?uri=OJ:C:2008:014:0006:01:SK:HTML (in Slovak) Penja V, Doboš J (1991) Mathematics (in Slovak). IV Ediˇcné stredisko VŠT Košice, p 229. ISBN 80–7099-067-8 ˇ Ríha J et al (2005) Risk analysis of flood areas (in Czech). Work and studies of the Institute of Water Structures FAST VUT v Brnˇe, Sešit 7, CERM, Brno, p 286. ISBN 80-7204-404-4 RÚVZ (Regional Public Health Office) (2013) Health protection at work and new classification, labeling and packaging of chemicals and mixtures. http://www.vzbb.sk/sk/aktuality/sos/ odborne_usmernenie_chl.pdf (in Slovak) Satrapa L (1999) Design and use of methodology for determination of potential flood damage (in ˇ Czech). In: Flood damage-determination of potential damage caused by floods. Prague, CVTVHS, Part 1, p 73–91. ISBN 80-02-01274-7 Satrapa L, Fošumpaur P, Horský M (2006) Flood control measures on the Elbe-risk analysis in the localities of Dˇecˇ ín (left bank) and Dˇecˇ ín (right bank) (in Czech). Praha, p 38 Satrapa L, Fošumpaur P, Horský M et al (2011) Assessing the effectiveness of flood protection actions in the framework of the activities of the strategic expert of the Flood Prevention Program in the Czech Republic (in Czech). In: River Basin and Flood Risk Management 2011-Proceedings ˇ of the scientific conference. Water Research Institute, Castá Papierniˇcka–Bratislava Simonová D (2012) Environmental-technical aspects, impacts and risks of floods. Diploma thesis. TUKE. (in Slovak) Švecová A, Zeleˇnáková M (2005) Water structures (in Slovak). Technical university of Kosice, Faculty of civil engineering Stavebná fakulta, Košice, p 190. ISBN 80-8073-443-7 SVP (Slovak Water Management Company) (1999) Flood protection program in the SR until 2010. Bratislava (in Slovak) http://www.svp.sk/svp/media%5Cpdf%5CProgram%20protipovod novej%20ochrany%202010.pdf STN 73 6100 Nomenclature of roads (in Slovak). Bratislava STN 73 6101 Design of roads and highways (in Slovak). Bratislava STN 75 0120 Water management. Hydraulic Engineering. terminology. July 2004. (in Slovak). Bratislava Trávnik I, et al (2003) Economics of construction business (in Slovak), 2nd edn. Bratislava, Slovak University of Technology in Bratislava, Faculty of Civil Engineering. ISBN 80-227-1895-5 http:// www.svf.stuba.sk/docs/dokumenty/skripta/ESP2003.pdf UNIKA, Institute of Building Economy (2012) Proceedings of average budget price indicators per unit of measurement. Buildings and civil engineering works according to the Classification of buildings. Bratislava (in Slovak) Vrijling JK, Van Hengel W, Houben RJ (1995) A framework for risk evaluation. J Hazard Mater 43(3):245–261 Vrijling JK, Van Hengel W, Houben RJ (1998) Acceptable risk as a basis for design. Reliab Eng Syst Safe 59(1):141–150 Zeleˇnáková M. Gaˇnová L, Purcz P (2012) Flood risk assessment as part of flood defence. In: SGEM 2012: 12th international multidisciplinary scientific geoconference, vol 3. STEF92 Technology Ltd., Albena, Bulgaria, p 679–686, ISSN 1314-2704 Zvijáková L (2013) The application of risk analysis in the environmental impact assessment (selected constructions). Dissertation, Technical University of Košice. (in Slovak)

Chapter 3

Application of Methodological Procedures in the Model Territory

In this chapter, the method for flood risk management as designed and described in Chap. 2 is applied in practice. For the practical application of the methodological procedure for the selection of flood protection measures aimed at reducing the potential adverse consequences of floods on people’s health, their property, and the environment, the town of Medzev in a sub-basin of the river Bodva has been chosen (Fig. 3.1). The town of Medzev was evaluated as an area with potentially significant flood risk as part of the preliminary flood risk assessment in Slovakia (Fig. 3.2).

3.1 Basic Data on the Territory The town of Medzev (Fig. 3.3) is located in the Kosice-Environs District within the Kosice Region of eastern Slovakia. The Bodva watercourse flows through the town with its left-bank tributaries Stoší potok (Brook), Porˇca Brook, Piverský Brook, Zlatná Brook and right-side streams Grunt Brook and Šugovský Brook. The watercourses of the river Bodva and Zlatna and Piverský Brooks are classified as significant watercourses included in the official list of national watercourses (Decree 211/2005 Coll.). As the town of Medzev is included on the basis of a preliminary flood risk assessment among the areas with an existing flood risk, it is essential to address this area as a matter of priority. In this area, it is necessary to build flood protection measures that will be effective not only in terms of protection, but also in economic, social, and environmental terms.

© Springer Nature Switzerland AG 2020 M. Zeleˇnáková et al., Flood Damage Assessment and Management, Water Science and Technology Library 94, https://doi.org/10.1007/978-3-030-50053-5_3

93

94

3 Application of Methodological Procedures in the Model Territory

Fig. 3.1 Location of the Bodva River Basin within Slovakia (arranged according to Bandura and Gallay 2013)

Fig. 3.2 Geographic areas with potentially significant flood risk in the Bodva Basin (arranged according to MoE SR 2011)

3.2 Application of Risk Management Methodology

95

Fig. 3.3 Location of Medzev within Slovakia

3.2 Application of Risk Management Methodology The aim of this part of the thesis is to quantify objectively the potential flood damage and the flood risk in the locality, which are subsequently classified in terms of probability and acceptability. According to the proposed methodology, the contents of this section are divided into three steps: 1. Estimation of potential flood damage to property, the environment, and human lives. 2. Calculation of flood risk based on assessment of the extent of damage for the designated floodplain and the probability of its occurrence. 3. Selection of cost-effective Flood Protection Measures (FPMs), which at the same time meet the levels of environmental and social risk acceptance as a result of floods. The result is a proposal for possible FPMs that will be effective in terms of protection, as well as from the economic, social, and environmental points of view.

96

3 Application of Methodological Procedures in the Model Territory

3.2.1 Estimation of Potential Flood Damage Estimation of potential flood damage in the designated floodplain is dealt with in accordance with the proposed methodology according to which three groups of impacts are assessed (Zeleˇnáková et al. 2017, 2018): • damage to property, • damage to the environment, and • loss of human life. The Evaluation of Damage to Individual Groups in the Area of Medzev Is Described in the Following Subchapters

3.2.1.1

Property Damage

Following the proposed methodology, the first group of damage to property consists of damage in three categories: damage to buildings, infrastructure, and agriculture. The methodology for quantifying flood damage to property is based on the procedures involving the application of loss curves (Sect. 2.1.1), mapping of the property distribution in the floodplain (Fig. 3.4), and a local survey of the site.

Fig. 3.4 Distribution of property in the town of Medzev (output from ArcGIS 10)

3.2 Application of Risk Management Methodology

97

The key documents for assessing the potential flood damage to the town of Medzev are the “Town Plan of Medzev” prepared by Envio, s.r.o. in 2013 and the flood maps provided by DHI Slovakia, s.r.o. A. Damage to buildings Description of the functional use of the town The town of Medzev is divided into two parts, both residential and economic. In the central part of the town, there is a Roman Catholic church with a small park and a cemetery nearby. In this area, to the southwest and northeast the urban zone is clearly linked to the original lines of family houses along the road, behind which there is more building land on both sides. Continuing this development in a northeasterly direction there are the buildings of the Mladost residential estate. Other areas of new residential buildings are located to the south of the church. The area of concentrated civic amenities comprises a multi-functional culture hall in the northeastern part and the campus of the schools. The areas of sport and recreation are mainly in the western part of Grunt. Areas of manufacturing are concentrated in the eastern part of the town territory (Envio 2013). Calculation of damage to buildings The calculation of flood damage to buildings is based on a simple relationship (2.18) where total damage is calculated as the sum of damage to individual buildings. For each building, the damage is calculated depending on the area of the building, the depth of flood, and the average purchase price per m2 of floor space in a one-storey building. For simplicity, and given the few details, only one type of building is considered, assuming a standard floor height of 3 m. The following is a sample calculation of minimum and maximum damage to a building with an ID number of 1 (Table 3.1): Table 3.1 Calculation of minimum DB (min) and maximum DB (max) damage to buildings for Q5 Q5 Building ID

Depth h[m]

Area Pi [m2 ]

S i (min) [-]

S i (max) [-]

CB [e/m2 ]

DB (min) [e]

DB (max) [e]

0

0.0452

129

0.0285

0.0429

525.24

1933.80

2909.76

1

0.0311

181

0.0280

0.0420

525.24

2665.16

3998.66

2

0.0000

330

0.0269

0.0401

525.24

4666.15

6953.83

3

0.1003

265

0.0304

0.0463

525.24

4230.66

6431.55

i

…

…

i

…

…

31

0.1945

692

0.0337

0.0521

525.24

12266.19

18922.61

32

0.0408

310

0.0284

0.0426

525.24

4617.03

6940.98

109753.3

166609.4

Suma

98

3 Application of Methodological Procedures in the Model Territory

Table 3.2 The resulting damage to buildings DB (min, max) for individual QN

QN%

Damage to buildings DB [e] Min

Max

Q5%

109753.30

166609.40

Q10%

136096.50

209278.70

Q50%

757690.00

1 178341.80

Q100%

838069.50

1 304582.10

Q1000%

1 121201.40

1 754652.30

The legend: Si (min) the value of the minimum loss depending on the depth h, Si (max) the maximum loss value depending on the depth h, C B unit (acquisition) price per 1 m2 of floor space in one storey determined by UNIKA (2012), DB (min) value of the calculated minimum damage to buildings, and DB (max) value of the calculated maximum damage to buildings. The table above shows that the damage calculation itself for each QN represents an enormous amount of data, as damage is calculated for each building individually. Table 3.2 therefore summarizes the results of total damage (min and max) on buildings per QN calculated using relationship (2.4) and Tables 2.3 and 2.4. B. Damage to infrastructure In the case of calculation of damage to different parts of infrastructure, the proposed methodology defines damage to the following types of construction. (a) Ground transport Description of roads The town of Medzev lies along the second class road no. II/548, which passes through from west to east and continues eastwards toward the city of Kosice (31 km). From the village of Jasov, another second class road no. II/550 leads in a southerly direction to the town of Moldava nad Bodvou (19 km). On the eastern edge of Medzev, there is an intersection on road II/548 where it is joined from the north by minor road III/5483, which ultimately connects with the local part of Bania Lucia, situated between the villages of Vysny Medzev and Jasov. Road II/550 passing through the cadastral area of Medzev corresponds approximately to a rating of C 7.5/70. Route II/548 is in good condition outside the town, with a relatively homogeneous cross section. In the section of road II/548 where it passes through the center of the town, it goes through a relatively narrow corridor defined on both sides by continuous construction of mostly

3.2 Application of Risk Management Methodology

99

family houses, but also by the civic amenities, which back directly onto the land. Road II/548 was refurbished in 2000, bringing it up to category B2-MZ 9.0/50. The carriageway has a width of 3.50 m, the total width of the asphalt road is 7.00 m + 2 × 0.50 m of concrete drainage strip, i.e., the width between the curbs is 8.00 m (Envio 2013). Calculation of damage to roads According to the proposed methodology, the calculation of damage to the roads from the total flooded area of all roads [m2 ] is based on the cost of loss (Table 2.4) for the given QN according to relationship 2.5. The area of flooded roads for each QN is calculated as the product of length and spare widths, so it is necessary to assign a spare width to each type of road. For local, purpose-built roads, and minor roads of Class III, the replacement width is taken from Table 2.3 in the range 24.5–7.5 m. Due to the fact that the width of the class ii roads is known, in the given area the actual path width is used, i.e., 8.00 m. The total calculated length of flooded roads, along with the associated replacement width and the calculated area for each flood scenario, is shown in Table 3.3. The resulting damage to the roads is calculated according to relationship (2.15) and Table 2.4. Here is an example of calculating the minimum and maximum damage for Q5 : Table 3.3 Calculation of total flooded road surface for individual QN QN%

Type of road

Q5%

Local, purpose-built road

Total Q10%

Local, purpose-built road

7.5

288.75

300.00 300.00

108.00

7.5

Class II roads

127.00

8

235.00

810.00 1016.00 1,826.00

Local, purpose-built road

202.50

7.5

1518.75

Class II roads

271.00

8

2168.00

473.50 Local, purpose-built road Class II roads

Total

40.00

Total flooded area A [m2 ]

287.75

Local, purpose-built road

Total Q1000%

7.5

40.00

Total Q100%

38.5

Replaceable width [m]

38.5

Total Q50%

Length [m]

3686.75

540.00

7.5

4050.00

472.50

8

3780.00

1012.50

7830.00

100

3 Application of Methodological Procedures in the Model Territory

Table 3.4 The resulting damage to road infrastructure (min, max) for each QN QN%

Flooded area P [m2 ]

Loss price LPRI [e/m2 ]

The resulting damage DRI [e]

Min

Max

Min

Max

Q5%

287.75

1.82

3.63

523.53

1043.16

Q10%

300.00

1.82

3.63

546.00

1,089.00

Q50%

1,826.00

1.82

3.63

3,323.32

6,628.38

Q100%

3686.75

1.82

3.63

6,709.89

13382.90

Q1000%

7830.00

1.82

3.63

14250.60

28422.90

The resulting road damage for individual QNs is summarized in Table 3.4. (b) Railways Description of rail transport A single-line railway line (RGT) no. 168 Moldava nad Bodvou—Medzev with rail freight transport to Medzev railway station 15,358 passes through the town with a branch to the quarry. Passenger transport has been excluded since 2003. The nearest railway station for passenger transport is in Moldava nad Bodvou (16 km) (Envio 2013). Calculation of damage to the railway Flooding of this railway line will not occur at any flow, so the damage to the railway is not quantified. (c) Infrastructure networks Description of infrastructure networks • Water The town has a gravitational water pipeline built in 1975. The source of water is the spring in Sugovska dolina (Sugov Valley). The water from the spring is transported to the town reservoir via a DN 200 storage tank. The reservoir is located south of the town. The upper limit of the pressure zone is 364 m with a low of 319 m above sea level. To the west of the town there is a wastewater treatment plant on the Medzev branch of the Kosice group water main. The sources of water are surface collections from the streams of Cierna Moldava, Porca, and Pivering west of the town. Another source is in the Golden Valley, north of the town, from where a pipeline runs through the western part of the town. Above the wastewater treatment plant there is a reservoir from which the water is transported to Kosice through a 700 mm duct via the town center (Envio 2013).

3.2 Application of Risk Management Methodology

101

• Sewage The town has had a public unified sewer system since 1994. Sewage and rainwater are discharged through the sewer network from Medzev and Vysny Medzev to a joint wastewater treatment plant located at the eastern edge of Medzev. The sewer network covers the central part of the town and the Mladost housing estate. The center of the town is served by an “A” collector made of DN 800 to 1200 mm pipes, which is connected to the WWTP administered by the East Slovakian Water Company a.s. (VVS) Kosice (Envio 2013). • Electricity The town is currently supplied with electricity from 22/0.4 kV distribution transformers. The transformer stations are powered by high-voltage (HV) connections, consisting predominantly of conductors at support points, to a lesser extent by highvoltage cable connections in the ground. Existing secondary low-voltage (NN) electrical wiring is installed via air guidance on concrete pillars as supporting points along the local roads. The central square has secondary LN substations in reserve in the town environs (Envio 2013). • Gas The city has had a mains gas network since 1995 at a pressure level of 0.3 MPa. Town customers are supplied with gas from a local medium-pressure (STL) network, either directly via STL gas connections, or via medium-pressure and STL/NTL pressure regulators. The source of natural gas is the VTL distribution pipeline to Medzev, which is connected to the Medzev regulatory station (RS) (Envio 2013). • Telecommunications The town is part of the Eastern Regional Technical Centre and has its own telephone exchange. The existing local telephone network (MTS) is largely made up of the country’s mains alongside the main transport route through the town, and partly airwired on wooden side-mounted masts from attendant switchboards located alongside local roads (Envio 2013). Calculation of damage to infrastructure networks It is clear from the survey of the site that the town is equipped with all kinds of infrastructure networks and therefore potential flood damage is calculated for all networks. The quantification of damage is based on the total length of the flooded networks, assuming that they are located parallel to the roads. With this in mind, calculating damage to infrastructure takes into account the calculated length of the road network in the floodplain for each QN , see. Table 3.5. The resulting damage is calculated according to the proposed relationship (2.7) and Table 2.7, taking into account the average cost of the DEN . The following is an example of calculating the resulting minimum and maximum damage for Q5 :

102

3 Application of Methodological Procedures in the Model Territory

Table 3.5 The resulting damage to the SIS infrastructure networks (min, max) for each QN QN%

Length L[m]

Loss price LPEN [e/m2 ]

The resulting damage DEN [e]

Min

Max

Min

Max

38.50

4.84

5.74

186.34

220.99

Q10%

40.00

4.84

5.74

193.60

229.60

Q50%

235.00

4.84

5.74

1,137.40

1,348.90

Q100%

473.50

4.84

5.74

2,291.74

2,717.89

Q1000%

1012.50

4.84

5.74

4,900.50

5,811.75

Q5%

Table 3.5 gives the calculation of the resulting damage (min. and max.) to the infrastructure networks for each QN . (d) Bridges There is no bridge in the flood zone, so damage to this type of construction is not quantified. A. Damage to agriculture In the eastern part of the cadastre there are large tracts of arable land which are managed by AGROMOLD, s.r.o. Moldava nad Bodvou, and which are used for the cultivation of food crops (Envi 2013). When evaluating damage to agriculture, the damage to plant production is based on the area of flooded agricultural land and the amount of financial loss from damaged crops. A sample calculation of the resulting damage (min and max) on plant production according to (2.1.1) and Table 2.10 for Q5 is the following:

The total calculated area of the flooded agricultural land together with the calculation of the resulting damage to plant production for the individual QN is shown in Table 3.6. The average cost of DCP is taken into account. Summary of the chapter The aim of this chapter was to give an estimation or rather a calculation of potential flood damage to property in the floodplain of Medzev (Fig. 3.5). Table 3.7 presents the values of potential flood damage in the range in which the actual damage (min,

3.2 Application of Risk Management Methodology

103

Table 3.6 The resulting damage to agriculture DCP (min, max) for individual QN QN%

Area P [ha]

Loss price LPCP [e/ha]

The resulting damage DCP [e]

Min

Max

Min

Max

Q5%

1.67

254.77

1,019.06

425.47

1,701.83

Q10%

2.29

254.77

1,019.06

583.42

2,333.67

Q50%

5.52

254.77

1,019.06

1,406.33

5,625.32

Q100%

6.93

254.77

1,019.06

1,765.56

7,062.29

Q1000%

9.42

254.77

1,019.06

2,399.93

9,599.92

max) in euros for individual flows Q5 , Q10 , Q50 , Q100 , and Q1000 should be calculated. The damage is listed for each category of property, as well as the total for the study area. Table 3.8 lists the extent of the property at flood risk corresponding to the calculated damage. The buildings are the number of the potentially flooded objects; the area of the roads is reported in the area of m2 of the potentially flooded roads. The extent of flooded infrastructure networks is derived from the length in meters of the roads paralleled by the networks. The extent of flooded agricultural land is expressed in hectares.

3.2.1.2

Environmental Damage

Description of potential sources of pollution In the town itself, the environment is in relatively good condition. To some extent there is pollution from a local factory. The town is situated in a relatively calm environment, away from the main traffic routes. The town ensures the collection and transport of municipal waste by contract with the company AVE—Kosice, by transporting it to a controlled waste landfill located in the cadastral territory of the village of Jasov belonging to AVE Jasov, s.r.o., where it is deposited. This landfill is classified as for non-hazardous waste. In the territory of the town, fly-tipping dumps are registered on Kováˇcská Street in a detached part of the Roma settlement (Envi 2013). As mentioned above, there is a Wastewater Treatment Plant (WWTP) in the eastern part of Medzev (Fig. 3.6). Basic data on this WWTP are presented in Table 3.9. There are three environmental burdens in Medzev, which are included in register A (probable environmental load), register B (environmental load), and register C (sanitized, reclaimed locality) (www.enviroportal.sk). The baseline data on these environmental burdens are obtained from the environmental load registered at www. enviroportal.sk and are shown in Fig. 3.7. Data publishing for the environmental burden included in Part A—Environmental Burden Register is not permitted without

104

3 Application of Methodological Procedures in the Model Territory

Fig. 3.5 The extent of flooded property in the study area of Medzev for individual QN (output from ArcGIS 9.3)

authorized entry. Pursuant to § 20 and Sect. (2) of Law No. 569/2007 Coll. (Geological Law), as amended (Law No. 384/2009 Coll.), information on likely environmental burdens is not available, and therefore only the data on environmental burdens included in Parts B and C are given in the next section. In the case of the Strojsmalt metalworking factory’s environmental burden (Fig. 3.8), which is included in the B and C register, the pollution point is the heavy

3.2 Application of Risk Management Methodology

105

Table 3.7 Resulting potential flood damage to individual property categories in the range of values min. (yellow) and max. (blue) Flow

Q5%

Damage [eur]

Min

Max

Min

Max

Min

Max

To buildings To infrastructure

Q10%

Q50%

109,753

166,609

136,097

209,279

757,690

1,178,342

Roads

523

1044

546

1088

3328

6638

Railways

0

0

0

0

0

0

Infrastructure networks

186

220

193

229

1139

1351

0

0

0

0

0

0

To agriculture

Bridges

425

1702

583

2334

1406

5625

Flood damage total

110,888

169,575

137,419

212,930

763,564

1,191,956

Flow

Q100%

Damage [eur]

Min

To buildings To infrastructure

Roads

Q1000% Max

Min

Max

838,069

1,304,582

1,121,201

1,754,652

6709

13,381

14,250

28,422

Railways

0

0

0

0

Infrastructure networks

2291

2717

4900

5812

Bridges

0

0

0

0

To agriculture

1766

7062

2400

9600

Flood damage total

848,835

1,327,742

1,142,752

1,798,486

Q1000%

Table 3.8 Range of endangered property for individual QN Flow QN

Unit

Q5%

Q10%

Q50%

Q100%

Damage To buildings To infrastructure

pcs

33

39

88

106

160

Roads

m2

287.75

300.00

1,826.00

3686.75

7830.00

Railways

m

0

0

0

0

0

Infrastructure networks

m

38.5

40.00

235.00

473.50

1012.50

Bridges To agriculture

pcs

0

0

0

0

0

ha

1.67

2.29

5.52

6.93

9.42

oil store, as well as the temporary fuel storage site, from which the soil, surface, and groundwater pollution was spread by oil. Another environmental burden is the fuel filling station (Fig. 3.9), which is classified as category C. Pollution of the bedrock environment and groundwater was caused by repeated releases of diesel and petrol from the underground tanks and from the surface of the operating space over a long period of time and with varying intensity.

106

3 Application of Methodological Procedures in the Model Territory

Fig. 3.6 Localization and details of WWTP Medzev

Table 3.9 Data on WWTP Medzev (MoE SR 2009) Location code

Operator name

Name

ID

River

A0020DVA

VVS a.s.—East Slovakian Water Company

WWTP Medzev

17,130

Bodva

River Km

Location at river

Outflow

Water type

Water body

32,6

Left bank

Outflow from WWTP

K2S

SKA0002

In the suburb of the town on Kovacska Street, next to the Strojsmalt factory, there is the Rosenberg—Slovakia industrial company (Fig. 3.10). The main production program of the company consists of castings made with pressure-casting technology, production of magnetic circuits, and components for fans. Determination of environmental consequences of floods The overall consequences are calculated as the sum of the assigned points by the individual sources of pollution presented in the flood area for a given QN (probability of flood occurrence) multiplied by the respective weight according to Table 2.10. The point classification of the results for each category of pollution source is shown in Table 3.10.

3.2 Application of Risk Management Methodology

107

Fig. 3.7 Data on environmental burdens in Medzev with their exact location (arranged according to www.enviroportal.sk)

In the floodplain for each QN there are no waste ponds or landfills, and moreover the WWTP is outside the floodplain area. The filling station also lies outside of the flooded area. These potential sources of pollution are therefore assigned a zero value (Table 2.10). Environmental burdens classified as category B are located in the flood zone for flows Q50% , Q100% , and Q1000% (Fig. 3.11). Each QN is assigned a 0.36 value for this source in subcategory B (Table 3.10). The Rosenberg industrial plant is also located in the flood zone for flows Q50% , Q100% , and Q1000% . In accordance with Law no. 277/2005 Coll., this factory is not included in any of the categories A or B, and therefore falls within the subclass “unclassified” in the assessment of consequences. The QN , namely, Q50% , Q100% , and Q1000% , is assigned a value of 1 in this row (not assigned) in Table 3.10. Due to the fact that a sewer system is built in the town of Medzev, it is assumed that the percentage of the population without connection to the sewer system is in the range from 0 to 40%, so each QN is assigned a value of 0.48 (Table 3.10). The percentage of flooded agricultural land out of the total flooded area does not exceed 40% at no flow rate, and therefore this diffuse source of pollution for each QN is assigned a value of 0.36 (Table 3.10).

108

3 Application of Methodological Procedures in the Model Territory

Fig. 3.8 Detail of environmental burden of Strojsmalt factory

The summation of the assigned points together with the calculation of the total value of the result is presented in Table 3.10. Based on Table 2.11 the calculated result is assigned to all QNs in the “marginal impact” category: the flooding of individual sources of pollution will cause only minimal or no degradation of the environment.

3.2.1.3

Losses of Human Life

According to the Population, Housing and Housing Census in 2011, Medzev had 4,261 permanent residents, of which 23.8% were in pre-productive age, 60.0% in productive age, and 16.2% in post-productive age (Envio 2013). The methodology for estimating losses of human life is dealt with in Sect. 2.1.3, which proposes a general relationship for the calculation of losses of human life as a result of floods. The calculations include data on the number of people affected during the floods and the economic damage calculated in the previous step for individual flood scenarios with Q5% , Q10% , Q50% , Q100% , and Q1000% return periods. The number of vulnerable population is determined for each QN based on the flooded area and population density determined according to Table 2.17 and Eq. (2.23). In accordance with Table 2.17, and on the basis of the number of inhabitants, the town of Medzev is included in the area with a population of 2000–5000

3.2 Application of Risk Management Methodology

109

Fig. 3.9 Detail of environmental burden of filling station

Fig. 3.10 Location and detail of the Rosenberg industrial plant

inhabitants, i.e., the population density is 20 persons/ha. The flooded area is calculated for each flood scenario based on map data. The total number of vulnerable inhabitants is shown in Table 3.11.

Sources of pollution

Sewage treatment plants

Filling stations

A2

A3

Waste landfills

Ponds

Population without sewage system

B1

B2

B3

Diffuse sources of pollution

Factories with the presence of hazardous substances

A1

Point sources of pollution

Sign

0.59

60–100%

0.12 0.29

4

1

40–60%

0–40%

3

0.59

–

0.29

0.12

1

Hazardous waste

5

3

0.38

Non-hazardous waste

Inert waste

–

Over 100,000 inhabitants

0.21 0.29

10,000–100,000 inhabitants

0.14

2000–10,000 inhabitants

5

0.5

Up to 2000 inhabitants

0.3

0.2

Weight

B

5

Point classification of hazard

A

Uncategorized

Partial category of source of pollution

Table 3.10 Calculation of the resulting consequences or the resulting negative impacts on the environment

0

0

0.48

0

0

0

0

0

0

0

0

0

0

0

0

Q5%

0

0

0.48

0

0

0

0

0

0

0

0

0

0

0

0

Q10%

0

0

0.48

0

0

0

0

0

0

0

0

0

0

0

1

Q50%

0

0

0.48

0

0

0

0

0

0

0

0

0

0

0

1

Q100%

(continued)

0

0

0.48

0

0

0

0

0

0

0

0

0

0

0

1

Q1000%

110 3 Application of Methodological Procedures in the Model Territory

Agriculture

Environmental burden

B4

B5

 consequence (Di )

Sources of pollution

Sign

Table 3.10 (continued)

0.59 0.12

Sanitized/reclaimed site (C)

0.29

Confirmed (B)

3

0.59

Likely (A)

60–100%

0,12

Weight

0,29

3

Point classification of hazard

40–60%

0–40%

Partial category of source of pollution

0.84

0

0

0

0

0

0.36

Q5%

0.84

0

0

0

0

0

0.36

Q10%

2.2

0.36

0

0

0

0

0.36

Q50%

2.2

0.36

0

0

0

0

0.36

Q100%

2.2

0.36

0

0

0

0

0.36

Q1000%

3.2 Application of Risk Management Methodology 111

112

3 Application of Methodological Procedures in the Model Territory

Fig. 3.11 Flooding of Strojsmalt Company (environmental burden C) for flows Q50, Q100, and Q1000

Table 3.11 Number of endangered inhabitants per QN QN

Q5%

Area of flooded area FA [ha]

6.83

Population density D [persons/ha]

Total number of endangered inhabitants EP [number]

20

137

Q10%

8.69

20

174

Q50%

19.24

20

385

Q100%

24.78

20

496

Q1000%

35.13

20

703

From the above estimation of the number of vulnerable inhabitants and the total damage to property (minimum), according to relationship (22), the loss of human lives (LOL) is shown in Table 3.12.

3.2.2 Flood Risk Calculation In this chapter, the economic and social flood risks and the environmental risk due to floods are determined in accordance with the procedures set out in Sect. 2.2. The risk is quoted for the current state, i.e., prior to implementation of the FPM, and for

3.2 Application of Risk Management Methodology

113

Table 3.12 The resulting loss of human life QN

Total number of endangered inhabitants EP

Calculated economic damage DE (min) [mil. e]

Resulting loss of human lives LOL [number]

x1

x2

Q5%

137

0.110888

0.100

Q10%

174

0.137419

0.107

Q50%

385

0.763564

0.138

Q100%

496

0.848835

0.156

Q1000%

703

1.142 752

0.189

Table 3.13 Resulting values of total economic risk ER and capitalized risk ERk [Eur/Year] Potential Risk [e/year] Cap. risk [e] protection ER pre-realization ER post-realization ER pre-realization ER post-realization k k rate FPM FPM FPM FPM FPM Q5%

72,493

58,365

4,738,101

3,814,712

Q10%

72,493

46,102

2,416,432

3,013,190

Q50%

72,493

16,508

2,416,432

1,078,925

Q100%

72,493

8494

2,416,432

555,191

Q1000%

72,493

0

2,416,432

0

Rate of protection of potential FPM

Risk [-]

Risk [-]

EnR before implementation of FPM

EnR after implementation of FPM

Q5%

0.317

0.228

Q10%

0.317

0.156

Q50%

0.317

0.041

Q100%

0.317

0.020

Q1000%

0.317

0

Table 3.14 Overall environmental risk rate EnR [-]

the status after realization of the FPM. The higher the proposed flood protection rate, the lower the flood risk rate after the measure is implemented. Table 3.13 shows the economic flood risk values calculated according to relationship (36) and the capitalized risk calculated from relationship (2.27) for Medzev. The minimum damage is taken from Table 3.7. Table 3.14 reports the calculation of the overall environmental risk due to floods, according to relationship 38 in Medzev.

114

3 Application of Methodological Procedures in the Model Territory

Table 3.15 Resulting values of social risk SR [persons/year]

Rate of protection of potential FPM

Risk [persons/year] Risk [persons/year] SR before implementation of FPM

SR after implementation of FPM

Q5%

0.031

0.021

Q10%

0.031

0.012

Q50%

0.031

0.003

Q100%

0.031

0.002

Q1000%

0.031

0

From the calculated number of victims, or rather loss of human life due to floods (Table 3.15), the total social risk in the Slovak Republic according to relationship 2.35 with the chosen coefficient of aversion k = 0 is determined for individual flood events. The resulting calculated values of total social risk for Medzev are shown in Table 3.15.

3.2.3 Selection of Effective Flood Protection Measures The objective of selecting effective flood protection measures in the study area depends on the answers to two fundamental questions: 1. Does it make sense to build an FPM in a given location? 2. For what rate of protection is the FPM designed? The answers to these questions are informed by the procedure described in Sect. 2.3, explaining how to evaluate the effectiveness of FPMs in terms of economic efficiency, rate of environmental risk, and acceptable levels of social risk. Based on these procedures, the effectiveness of the FPM in the area of Medzev is described in the following section.

3.2.3.1

Economic Efficiency

To assess the economic efficiency of an FPM in the study area, it is necessary to use cost/benefit analysis (Sect. 2.3.1). Given the fact that the actual proposed FPMs and actual costs are not known, the economic efficiency cannot be evaluated. However, it is possible to determine at least the minimum cost of realizing FPMs (or benefits), which are calculated as the difference in capitalized risk before and after FPM realization. The calculated final cost is shown in Table 3.16. Figure 3.12 illustrates the town of Medzev, where flood damage occurs already at Q5% .

3.2 Application of Risk Management Methodology Table 3.16 The resulting limit costs for implementation of the FPM

115

Rate of protection of potential FPM

Limit costs/benefit [e]

Q5%

923,389

Q10%

1,724,911

Q50%

3,659,177

Q100%

4,182,910

Q1000%

4,738,105

Fig. 3.12 Reduction of present value of risk due to realization of FPM to Q50% adjusted according to (Satrapa et al. 2006)

The technical solution of FPM consists, for example, in the construction of a dyke which will increase the current unsuitable flood protection rate up to Q50% . Figure 35 shows that no damage will be generated in the town until the flow of Q50% , and once the proposed flow is exceeded, the damage in the town will be practically the same as if the FPM did not exist. The benefit of the proposed FPM to Q50% is then given by the difference in capitalized risk before and after FPM realization.

3.2.3.2

Rate of Acceptability of Environmental Risk

The environmental performance of the FPM in Medzev is determined as the measure of reduction of environmental risk (M) calculated in percentage using relationship (2.39) (Sect. 2.3.2). The resulting values are shown in Table 3.17. Table 3.17 shows that through construction of an FPM with flood protection set for Q10% , the environmental risk as a result of floods is reduced by up to 51%.

116

3 Application of Methodological Procedures in the Model Territory

Table 3.17 Resulting measure of environmental risk reduction

3.2.3.3

Rate of protection of potential FPM

Reduction of environmental risk M [%]

Q5%

28

Q10%

51

Q50%

87

Q100%

94

Q1000%

100

Level of Social Risk Acceptability

The level of social risk acceptance as determined in the town of Medzev following the procedure in Sect. 2.3.3 and relationship (2.43) is shown in Table 3.18. After comparing the calculated values of the annual social risk for the town of Medzev, i.e., the present state (Table 3.18) with the value of acceptable social risk of 0.0397 persons/year, we can state that the value of the social risk does not fall below unacceptable limits. It is necessary to implement flood protection measures that would reduce the social risk. Summary of the chapter In view of these results, we can say that in the locality of Medzev it is important to build an FPM, especially in terms of protection of property and the environment. Concerning the second question, for what protection rate the FPM has to be designed, the economic factor is decisive in this case, as it is not necessary to reduce the social risk, and the environmental risk is reduced already in Q5. Since the actual proposed FPMs and actual costs are not known, this efficiency cannot be evaluated. For efficiency gains, it is necessary to obtain evidence of proposed flood protection solutions and then evaluate the economic efficiency of each of the FPM options considered. The results can be subsequently applied when selecting the final solution of FPM at the solution site. Based on the current state of the existing modifications, we propose the following possibilities of preventive flood protection measures in the area of Medzev: Table 3.18 Comparing the social risk with acceptable social risk SRaccep Rate of protection of potential FPM

SR before implementation of FPM

SR after implementation of FPM

SR < SRaccept. = 0,0397 (persons/year)

Q5%

0.031

0.021

Acceptable

Q10%

0.031

0.012

Acceptable

Q50%

0.031

0.003

Acceptable

Q100%

0.031

0.002

Acceptable

Q1000%

0.031

0.00

Acceptable

3.2 Application of Risk Management Methodology

117

• removing deposits from the riverbed and plants from the banks of the watercourse to ensure full flow capacity of the watercourse channel, • adapting the untreated sections of the watercourse, for example, reinforcing the slopes of the riverbed, and • constructing a water retention structure above the town, which would reduce the maximum flow at elevated water levels.

References Decree of the Ministry of the Environment of the Slovak Republic No. 211/2005 Coll. establishing a list of watercourses of major importance for water management and watercourses. (in Slovak) Zeleˇnáková M, Gaˇnová L, Purcz P, Hronský M, Satrapa L, Blišˇtan P, Diaconu DC (2017) Mitigation of the adverse consequences of floods for human life, infrastructure, and the environment. Nat Hazards Rev 18(4):17002–17002 Zeleˇnáková M, Gaˇnová L, Purcz P, Hronský M, Satrapa L (2018) Determination of the potential economic flood damages in Medzev, Slovakia. J Flood Risk Manag 11(2):1–10 UNIKA, INSTITUTE OF BUILDING ECONOMY (2012) Proceedings of average budget price indicators per unit of measurement. Buildings and civil engineering works according to the classification of buildings. Bratislava (in Slovak) ENVI, s.r.o. (2013) Land use plan of Medzev. Surveys and analyzes (in Slovak) http://medzev.sk/ uzpmedzev-par.pdf Bandura P, Gallay M (2013) Digital morphotectonic analysis of the Bodva basin (in Slovak). In: 16. year of students’ conference GISáˇcek. http://gis.vsb.cz/GISacek/GISacek_2013/referaty/ban dura.pdf MoE SR (2011) Map of potentially significant flood risk. http://www.minzp.sk/files/sekcia-vod/cia stkove-povodie-bodvy-iii-spa-1997-2010.pdf (in Slovak) Satrapa L, Fošumpaur P, Horský M (2006) Flood control measures on the Elbe-risk analysis in the localities of Dˇecˇ ín (left bank) and Dˇecˇ ín (right bank) (in Czech). Praha, p 38 MoE SR (2009) Bodva river basin management plan. http://www.vuvh.sk/download/RSV/07_ PMP_Bodva/01_Plan%20manazmentu%20ciastkoveho%20povodia%20Bodva/PMCP_Bodva. pdf (in Slovak)

Chapter 4

Conclusion

Flood events have a very special place in the field of natural disasters, the frequency of which has been increasing over the last decades, and their consequences account for 31% of economic losses. For these reasons too, flood protection solutions are taking on an increasingly international dimension, and there is increasing pressure to implement system-wide, comprehensive measures. The transition from flood protection to comprehensive flood management is reflected most in Directive (2007)/60/EC on flood risk assessment and management. The Directive has strengthened the convergence of national approaches to flood risk assessment and management, and has also brought parallel developments in the field of flood risk assessment and flood risk management in the member states of the European Union. Before the proposal of the methodology itself, the first part of this book presents a review of available documents concerning flood risk, risk analysis, and also the legal regulation of flood risk management in the Slovak Republic. In the last part, a methodical procedure is proposed and applied in the model area. The evaluation of potential flood damage and subsequent determination of the flood risk rate was carried out for the town of Medzev, which was evaluated as an area with existing potentially significant flood risk in the framework of the preliminary flood risk assessment in Slovakia. In view of the results obtained, it was concluded that it is important to install Flood Protection Measures (FPM) in the area of the town, especially with regard to protection of property and the environment. As there is no need to reduce social risk, and the level of environmental risk is already reduced at Q5, economic efficiency is a decisive factor in choosing an effective FPM. At the time of doing the research, the actual proposed FPMs were not known, and therefore the actual costs in the flood protection area were not known, so it was not possible to evaluate this effectiveness. Therefore, only variants of potential FPMs which could be implemented in Medzev are proposed. In order to determine the economic efficiency, it is necessary to obtain data on the costs of proposed FPM solutions, and subsequently to evaluate the economic efficiency of individual assessed variants of FPM.

© Springer Nature Switzerland AG 2020 M. Zeleˇnáková et al., Flood Damage Assessment and Management, Water Science and Technology Library 94, https://doi.org/10.1007/978-3-030-50053-5_4

119

120

4 Conclusion

The book addresses the current issue of floods, implementation, and subsequent updating of Directive (2007)/60/EC. The issues presented will contribute to meeting and updating the objectives of the Directive. The book focuses on • Overview of the current state of scientific knowledge in the field of flood risk assessment and management. • Analysis and overview of risk analysis methods, approaches, and tools applicable in the flood risk management process. • Overview of the legislation on flood risk management mainly in the Slovak Republic and its compliance with the requirements of Directive (2007)/60/EC. • Proposal of methodology for determining potential flood damage to property, environment, and human life in the conditions of the Slovak Republic. • Proposal for a procedure to determine the level of flood risk in relation to the flood damage identified and a proposal for a procedure for selecting effective flood control measures. • Implementation of the proposed procedures through geographic information systems, in particular, ArcGIS. • Presentation of potential flood control measures. For existing as well as proposed methodologies, improvements can be recommended which include the following tasks: • Extend and refine the calculation of flood damage in some assessed asset categories (e.g., buildings). • Extend flood event records by processing databases and subsequently verify the model for calculating the loss of human life. • Clarify and elaborate in more detail the methodology for assessing the negative impacts of floods on the environment and its individual components. The present work deals with the current topic of floods, which arises not only from their occurrence, but also due to the implementation of the said Directive (2007)/60/EC. The main aim of the thesis is to propose a methodical procedure for flood risk management which can be used in practice, if available. Knowledge about the potential flood damage to property, the environment and human lives is particularly important for the professional public, especially when deciding whether to build FPMs and whether the proposed FPMs will be profitable.

Reference Directive (2007)/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks (in Slovak)