MANAGEMENT OF FLOOD RISK WITH SPATIAL PLANNING Herath Mudhiyanselage Malani Herath 158039L Degree of Doctor of Philosophy in Civil Engineering Department of Civil Engineering University of Moratuwa Sri Lanka December 2021 MANAGEMENT OF FLOOD RISK WITH SPATIAL PLANNING Herath Mudhiyanselage Malani Herath 158039L Thesis submitted in partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Civil Engineering Department of Civil Engineering University of Moratuwa Sri Lanka December 2021 i DECLARATION OF CANDIDATE AND SUPERVISOR “I declare that this is my work and this thesis does not incorporate without acknowledgment any material previously submitted for a Degree or Diploma in any other University or institute of higher learning and to the best of my knowledge and belief it does not contain any material previously published or written by another person except where the acknowledgment is made in the text. Also, I hereby grant to the University of Moratuwa the non-exclusive right to reproduce and distribute my thesis/dissertation, in whole or in part in print, electronic, or another medium. I retain the right to use this content in whole or part in future works (such as articles or books).” ………………………………….. …….…………………….. Signature Date The above candidate has researched the Ph.D. Thesis under my supervision. Name of the supervisor:Professor R.L.H.L Rajapakse ………………………………….. ………………………………. Signature of the supervisor Date 25.12.2021 ii ACKNOWLEDGEMENTS First of all, I would like to express my heartfelt gratitude to Emeritus Professor N.T.S Wijesekera, for his valuable contribution and support, motivation, patience, and immense knowledge, and for guiding me throughout the whole study. His supervision helped me immensely at all times, during the research as well as in the writing of my thesis. I could not have imagined a better mentor to guide me throughout this study. I am deeply in debt to my present supervisor, Professor R.L.H. Lalith Rajapakse, Department of Civil Engineering, University of Moratuwa for his patient and steadfast support to finish this study. I would also like to take this opportunity to express my deepest gratitude to my external reviewer Dr. (Mrs.) T.N. Wickramarachchi for her excellent guidance and encouragement provided throughout the whole study. I would like to take this opportunity to convey my heartfelt thankfulness to Professor J.N Munasinghe, Department of Town and Country Planning, University of Moratuwa. Further, I offer my sincere gratitude to Professor Dileeka Dias, Former Dean, and Professor Ajith de Alwis, Dean, Faculty of Graduate Studies, University of Moratuwa, Professor L.W.P.R. Udayanga, Director Postgraduate Studies Division, Professor SAS Kulathilake, Former Head, Professor Mrs. Chintha Jayasinge, Head, Department of Civil Engineering, Professor J.C.P.H. Gamage, Former Research Coordinator, and Dr. T.M.N. Wijayaratna, Research Coordinator, Department of Civil Engineering. My deepest gratitude is conveyed to all the staff members of the UNESCO Madanjeet Singh Center for South Asia Water Management (UMCSAWM) and the Department of Town and Country Planning, University of Moratuwa. I am much grateful for all of the people who have contributed their valuable time, energy, ideas, experience, and encouragement to help me complete this study. I would also like to express my heartfelt gratitude to my mother, my family for their spiritual support, understanding and for all the strength you gave throughout my research. iii ABSTRACT Management of Flood Risk with Spatial Planning Flood risk has become a significant issue particularly in urban regions of Asia. Climate change will intensify existing flood vulnerability and further strengthen it due to socio-economic inequalities. A new set of problems are created by the traditional decision-making of flood management in the face of climate change and rapid urban development. The concept of the socio-ecological system suggests that resilience is the key to managing complex systems and reducing flood vulnerability. In addition, recognizing the significance of nonlinear and non- stationary interactions of flood risk in decision making has highlighted the transition of flood management towards Flood Risk Management (FRM). Acknowledging the uncertainty associated with flood risk has become a key aspect in decision-making. Decision-makers agree on the need for adaptive and integrated policies and strategies of FRM rather than modifying the flood and making it easier to cope with by eliminating the highest probability of floods. Flood resilience embeds the incorporation of spatially distributed land-use policies, strategies, and guidelines which are a must for the management of flood vulnerability. As a result, the characterization, assessment, and management of flood risk were subjected to a critical review during the past years. Risk-based flood management is yet in its early period of development. Though the theory has advanced over the years, there still are visible shortcomings in the operationalization of the concepts and methods, mainly due to the lack of a framework for clear recognition and understanding of the components of the FRM system. The FRM and spatial planning domains have developed their knowledge bases separately over a long period. Recently, FRM and spatial planning have begun to share a similar perspective in the decision-making process. The role of spatial planning as an integrated planning tool has been emphasized in the decision-making of flood risk management. It is largely evident that as at present, the role of spatial planning in flood risk management remains inadequate mainly because of the absence of a common framework for stakeholders’ integration. The main objective of this research is to identify the complete FRM system and its components with recommendations for its operationalization. This research has developed a solution model to structure the complexity of the planning process of FRM. The criteria and sub-criteria of the conceptual framework of the decision model have been identified based on the systematic literature review. Further, the criteria and sub-criteria of the conceptual framework have been selected and prioritized using the Delphi technique and Analytical Hierarchical Process (AHP). Forty-two experts have participated in this research and the established framework has been validated using a case study. Panadura urban area which is located in the coastal wet zone and Colombo Metropolitan Region has been selected as the case study area for application of the framework. This research has established a methodological framework for the operationalization of FRM. The main criteria which determine the practicing of FRM are the conceptualization of flood risk in the planning process, assessment of flood risk in the planning process, as well as the discourse of the governance structure, and the available participatory tools in the context. This study has identified and prioritized sixteen sub-criteria to manage the uncertainty in the planning process. The established framework can be used to identify the strengths and the weaknesses of the planning process in a given context and to guide the planning process to operate risk-based flood management objectives, strategies, and guidelines. The established framework can be used to evaluate the alternative options of flood risk management for achieving flood resilience. The case study has revealed that the existing decision-making process of FRM does not recognize the complex interdependencies between flood risk, spatial form, and spatial planning. As a result, the current practices of FRM are unable to achieve flood resilience. Therefore, this research recommends the integration of FRM with spatial planning. The developed framework is more sensitive to the governance structure of the context, therefore more case studies are needed to conduct in different governance contexts for further refine Keywords: AHP, Delphi, Framework, Integration, Nonlinearity, Stakeholders, Uncertainty iv DECLARATION OF CANDIDATE AND SUPERVISOR ......................................... i ACKNOWLEDGEMENTS ......................................................................................... ii ABSTRACT ................................................................................................................ iii TABLE OF CONTENTS ............................................................................................iv LIST OF FIGURES ......................................................................................................x LIST OF TABLES ......................................................................................................xi LIST OF APPENDICES...........................................................................................xiii LIST OF ABBREVIATIONS .................................................................................... xv CHAPTER 1 - INTRODUCTION ............................................................................... 1 1.1 Background ........................................................................................................ 1 1.2 Problem Statement ............................................................................................. 7 1.3 Objective ............................................................................................................ 7 1.4 Specific Objectives............................................................................................. 8 1.5 Thesis Outline .................................................................................................... 8 CHAPTER 2 - LITERATURE REVIEW .................................................................. 11 2.1 Decision Making Framework ......................................................................... 11 2.2 Decision-making Frameworks of Flood Risk Management (FRM) ................ 12 2.3 Traditional Decision-making Frameworks of Flood Management .................. 13 2.3.1. Conceptualization of flood risk ................................................................ 13 2.3.2 Assessment of flood risk ........................................................................... 13 2.3.3. Flood management ................................................................................... 14 2.3.4 Limitations of the rationalist approach in decision making ...................... 15 2.4 Constructivist Approach to Flood Management .............................................. 19 2.4.1 Flood vulnerability .................................................................................... 20 2.4.2 Flood vulnerability assessment ................................................................. 24 2.4.3 Limitations of assessment and management of flood risk ........................ 27 2.5 Transformation of Flood Risk Management Towards an Adaptive and Integrated Process ............................................................................................................. 33 TABLE OF CONTENTS v 2.6 Components of the Flood Risk Management System ...................................... 34 2.7 Current Status of Knowledge Related to the Components of the Flood Risk Management .................................................................................................... 36 2.7.1 Flood risk .................................................................................................. 36 2.7.2 Flood risk management objectives ............................................................ 38 2.7.3 Flood risk management options ................................................................ 40 2.7.4 Assessment of risk .................................................................................... 43 2.7. 5 Evaluation of the merits long term and short term of flood management goals ........................................................................................................ 46 2.7.6 Evaluation of the merits long term and short term of flood management strategies ................................................................................................. 48 2.7.7 Development of guidelines ....................................................................... 52 2.7.8 Achievements of objectives ...................................................................... 55 2.8 Current Status of the Flood Risk Management ................................................ 58 2.9 Interplay between Spatial Planning and Flood Risk Management .................. 62 2.9.1 Spatial planning and flood risk management in the early period .............. 62 2.9.2 Limitations of traditional spatial planning practices ................................. 63 2.9.3 Integrating of flood risk management and spatial planning ...................... 64 2.10 Challenges for Operationalization of the Flood Risk Management System .. 69 2.10.1 Stakeholders' plural understanding on interdependencies of land and water ................................................................................................................ 70 2.10.2 Public indifference to natural disasters ................................................... 70 2.10.3 Territorial development ..........................................................................71 2.10. 4 Institution culture ................................................................................... 71 2.10.5 Shared dilemmas in the planning process ............................................... 71 2.10.6 Lack of political support ......................................................................... 72 2.10.7 Over-reliance on top-down planning ...................................................... 72 2.10.8 Lack of flexibility of planning process ................................................... 73 2.10.9 Planning context ...................................................................................... 73 2.10.10 Flexibility of governance system .......................................................... 74 2.10.11 Lack of participatory governance tools ................................................. 75 vi 2.11 Gap of the Current Status of Operationalization of Flood Risk Management with Spatial Planning ....................................................................................... 76 2.11.1 Variety of stakeholders ........................................................................... 76 2.11.2 Stakeholder participation ........................................................................ 77 2.11.3 Joint definition ........................................................................................ 78 2.11.4 Absence of a common framework .......................................................... 79 2.11.5 Reframing planning ................................................................................. 80 2.11.6 Governance arrangement and participation of stakeholders ................... 81 2.11.7 Absence of guidelines ............................................................................. 82 2.11.8 Adaptive capacity .................................................................................... 83 2.12 Need of Research ........................................................................................... 83 CHAPTER 3 - METHODOLOGY ............................................................................ 86 3.1 Development of a Framework .......................................................................... 86 3.2 Development of a Decision Making Framework in Flood Risk Management 88 3.3 Application of Multi-Criteria Decision Making (MCDM) .............................. 88 3.4 Development of Decision Making Framework with Analytic Hierarchical Process (AHP) ................................................................................................. 89 3.5 Application of AHP in Flood Risk Management ............................................ 93 3.6 Methodology of the AHP ................................................................................. 93 3.6.1 Develop a hierarchical structure of the problem ....................................... 93 3.6.2 Literature review to extract possible criteria and sub-criteria ................... 94 3.6.3 Setting up the decision hierarchy using the Delphi technique and AHP .. 94 3.6.4 Pairwise comparison ................................................................................. 97 3.6.5 Synthesis of priorities .............................................................................. 103 3.6.6 Checking the Consistency Ratio ............................................................. 104 3.7 Validation of the Developed Framework ....................................................... 104 3.7.1 Validation with the case study ................................................................ 104 3.7.2 Selection of case study for validation ..................................................... 105 3.7.3 Stakeholders selection for validation of the decision model ................... 106 3.7.4 Preparation of questions for validation ................................................... 107 CHAPTER 4 - ANALYSIS ..................................................................................... 109 vii 4.1 Development of the Framework..................................................................... 109 4.1.1 Structure of the framework for operationalization of flood risk management .............................................................................................................. 109 4.1.2 Governance Context ................................................................................ 111 4.2 Adaptive and Integrated Planning Process ..................................................... 113 4.2.1 Conceptualization of flood risk management (FRM) ............................. 113 4.2.2 Assessment of the planning process ........................................................ 114 4.3 Adaptive and Integrated Governance System / Planning Context ................. 116 4.3.1 Discourses of Stakeholders ..................................................................... 116 4.3.2 Participatory governance arrangements .................................................. 117 4.4 Conceptualization of flood risk ...................................................................... 118 4.4.1 Flood risk as a complex phenomenon ..................................................... 118 4.4.2. Scale sensitivity of flood vulnerability and risk ..................................... 119 4.4.3 Inherent uncertainties associated with flood risk .................................... 120 4.4.4 Flood risk management as socially assesses, integrated and adaptive process .............................................................................................................. 121 4.5 Place-based Assessment ................................................................................. 122 4.5.1 Adaptive capacities to maintain the ecological functions of the floodplains .............................................................................................................. 122 4.5.2 To develop diverse flood risk management options for different uncertain futures ................................................................................................... 126 4.5.3 Hydrological interactions of floodplains ................................................127 4.5.4 Socio-spatial interactions of floodplain .................................................. 128 4.6 Discourses of Stakeholders ............................................................................ 130 4.6.1 Social Learning ...................................................................................... 131 4.6.2 Multilevel governance systems ............................................................... 131 4.6.3 Flexibility in governance arrangements for continuous learning and experimentation .................................................................................... 132 4.6.4 Local initiatives ....................................................................................... 133 4.7 Integrated and Adaptive Governance Mechanism ......................................... 134 viii 4.7.1 Integration among the land and water institutions at all scales and levels .............................................................................................................. 134 4.7.2 Integrated goal setting and catchment-scale approach ............................ 135 4.7.3 Multiple Governance ............................................................................... 136 4.7.4 Local stakeholders for participation ....................................................... 136 4.8 Proposed Framework for Flood Risk Management ....................................... 137 4.9 Calibration of the Proposed Framework ........................................................ 141 4.10 Experts Consensus on the Criteria and Sub-Criteria of the Framework ...... 141 4.10.1 Prioritization of the main criteria .......................................................... 147 4.10.2 Prioritization of sub-criteria of conceptualization................................. 153 4.10.3 Prioritization of sub-criteria of place assessment.................................. 156 4.10.4 Prioritization of sub-criteria of discourse .............................................. 169 4.10.5 Prioritization of sub-criteria of participatory tools................................165 4.11 Ranking of Sub criteria.................................................................................169 4.12 Relative Importance of the Criteria and the Sub-Criteria for Criteria for Implementation of FRM ................................................................................ 181 CHAPTER 5 - VALIDATION OF FRAMEWORK ............................................... 181 5.1 Increasing of Flood Damage .......................................................................... 181 5.2 Urban Flood Disasters .................................................................................... 181 5.3 Increasing of Urban Flood Risk in the Colombo Metropolitan Region (CMR) ....................................................................................................................... 181 5.4 Increasing Flood Risk in Bolgoda River Basin .............................................. 181 5.5. Selection of Case Study ................................................................................ 183 5.5.1. Panadura Urban area in the Bolgoda Basin............................................ 183 5.5.2 Land use changes over the period in Panadura ....................................... 185 5.5.3 Karapen Ela ............................................................................................. 187 5.5.4. Flood risk management measures in Panadura ...................................... 192 5.6. Land-Use Regulations in The Panadura Area ............................................... 193 5.7 Role of Different Stakeholders in the Flood Risk Management ....................195 ix 5.8 Evaluation of the Existing Decision-Making Process for Operationalization of Flood Risk Management ................................................................................ 197 5.9 Assessment of the Existing Decision-Making Process for Operationalization of Flood Risk Management ................................................................................ 207 5.10 Review of Flood Risk Management (FRM) Practices in Panadura ............. 209 5.10.1 Conceptualization of flood risk ............................................................ 209 5.10.2 Place-based assessment ........................................................................ 218 5.10.3 Discourse of the stakeholders................................................................ 222 5.10.4 Participatory Tools ................................................................................ 226 5.11 Validation of the Framework ....................................................................... 233 CHAPTER 6 - DISCUSSION...................................................................................234 6.1 Uncertainty of Flood Risk ............................................................................. 235 6.2 Risk-based Flood Management ...................................................................... 235 6.3 Socio-Spatial Integration for Risk-based Flood Management ....................... 237 6.4 Operationalization of Flood Risk Management with Spatial Planning ......... 238 6.5 Transformation of Spatial Planning for Stakeholder Integration ................... 239 6.6 Managing of Flood Risk with Spatial Planning ............................................. 241 6.7 Framing of Complex Decision Making with AHP ........................................ 243 6.8 Conceptualization and Calibration of the Framework ................................... 244 6.9 Validation of the Framework ......................................................................... 245 6.10 Selection of Case Study for Validation ........................................................ 246 6.11 Applicability of the Developed Framework for Operationalization of Flood Risk Management .......................................................................................... 248 6.12 Gaps of Existing Practices of FRM ............................................................. 250 6.13 Recommendations for Sustainable Management of Flood Risk .................. 252 6.14 Future Research Needs ................................................................................256 CHAPTER 7 - CONCLUSIONS ............................................................................. 258 REFERENCES.........................................................................................................260 APPENDIX .............................................................................................................. 294 x LIST OF FIGURES Figure 1.1 Research methodology .............................................................................. 9 Figure 2.1 Decision-making process of Flood Risk Management ............................. 12 Figure 2.2 Transformation of decision-making process of FRM ............................... 32 Figure 2. 3 Identification of flood risk management system………………............. 35 Figure 3.1 Schematic diagram of the framework development process.....................91 Figure 3.2 Methodology flow chart............................................................................92 Figure 3.3 Hierarchical structure................................................................................93 Figure 3.4 Pairwise comparison matrix ...................................................................103 Figure4.1Framework for operationalization of flood risk management.................. 110 Figure 4.2: Main Criteria of the Framework for operationalization of flood risk management..............................................................................................................113 Figure 4.3 Sub criteria of conceptualization..............................................................122 Figure 4.4 Sub criteria of the place-based Assessment ............................................ 129 Figure 4.5 Sub criteria of discourse of the stakeholders .......................................... 134 Figure 4.6 Sub criteria of participatory governance context .................................... 137 Figure 4.7 Criteria and sub-criteria of the framework for operationalization of flood risk management .................................................................................... 140 Figure 4.8 Prioritization of the main criteria ............................................................ 152 Figure 4.9 Prioritization of the sub-criteria of Conceptualization .......................... 156 Figure 4.10 Prioritization of the sub-criteria of Place assessment .......................... 169 Figure 4.11 Prioritization of the sub-criteria of Discourse ................................... 169 Figure 4.12 Prioritization of the sub-criteria of Participatory tools ...................... 181 Figure 5.1 Flooded areas around Metropolitan Colombo Area .............................. 181 Figure 5.2 Hydrological pattern of the Colombo metropolitan region ................... 181 Figure 5.3 Urban areas in Bolgoda river basin ........................................................ 182 Figure 5.4 Distribution of human settlement over the Bolgoda river basin .......... 183 Figure 5.5 Population Density of the Bolgoda River Basin .................................... 184 Figure 5.6 Elevation of the area.................................................................................184 Figure 5.7 Flood damage in 2016 May ( Field survey)............................................186 Figure 5.8 Flood affect areas of Karepen Ela ......................................................... 188 xi Figure 5.9 Flood damage in the vicinity of the Karepen Ela. .................................. 189 Figure 5.10: Land use changes in the catchment area of Karepen Ela in 1994.........190 Figure 5.11 Land use changes in the catchment area of Karepen Ela in 2004 ...... 191 Figure 5.12 Land use changes in the catchment area of Karepen Ela in 2020 ....... 192 Figure 5.13 Bolgoda Environmental Protection Area (EPA) ...............................192 Figure 5.14 Floodplain guidelines ......................................................................... 194 Figure 5.15 Land use zoning plan ............................................................................ 195 Figure 5.16 Hydrological pattern of the study area.................................................. 211 xii LIST OF TABLES Table 2.1 Critical Component of the Flood Risk Management ................................. 59 Table 3.1 Classification framing of complex problems ............................................. 86 Table 3.2 Approaches used for the development of methodological frameworks.......87 Table 3.3 Selection of experts .................................................................................... 98 Table 3.4 Priority values of the main criteria ........................................................... 100 Table 3.5 Priority values of the sub-criteria of conceptualization ........................... 100 Table 3.6 Priority values of the sub-criteria of place assessment .......................... 100 Table 3.7 Priority values of the sub-criteria of discourse ........................................ 101 Table 3.8 Priority values of the sub-criteria of participatory tools .......................... 101 Table 3.9 Pairwise comparison matrix structure ...................................................... 101 Table 3.10 Comparative Judgment Structure of Criteria ......................................... 102 Table 3.11 Saaty’s nine-point ratio scale (Saaty, 1987)........................................... 102 Table 3.12 Stakeholders related to the flood risk management in Panadura ........... 106 Table 4.1 Results of Expert consensus (overall assessment) ................................... 141 Table 4.2 Results of Expert consensus (Engineers) ................................................. 142 Table 4.3 Results of Expert consensus (Town Planners) ......................................... 143 Table 4.4 Pairwise comparison matrix for main criteria .......................................... 147 Table 4.5 Normalized matrix for main criteria ........................................................ 148 Table 4.6 Priority vector for main criteria ............................................................... 148 Table 4.7 Principal Eigen value calculation for main criteria .................................. 148 Table 4.8 Main criteria weights obtained from AHP ............................................... 149 Table 4.9 Pairwise comparison matrix for sub-criteria of conceptualization .......... 153 Table 4.10 Normalized matrix for sub-criteria of conceptualization ....................... 153 Table 4.11 Priority vector for sub-criteria of conceptualization .............................. 153 Table 4.12 Principal Eigenvalue calculation for sub-criteria of conceptualization . 154 Table 4.13 Weights of Sub criteria conceptualization obtained from AHP ............. 155 Table 4.14 Pairwise comparison matrix for sub-criteria of Place assessment ......... 156 Table 4.15 Normalized matrix for sub-criteria of Place assessment ........................ 169 Table 4.16 Priority vector for sub-criteria of Place assessment ............................... 169 Table 4.17 Principal Eigenvalue calculation for sub-criteria of Place assessment .. 169 xiii Table 4.18 Weights of sub-criteria Place assessment obtained from AHP .............. 169 Table 4.19 Pairwise comparison matrix for sub-criteria of discourse ..................... 169 Table 4.20 Normalized matrix for sub-criteria of discourse .................................... 169 Table 4.21 Priority vector for sub-criteria of discourse ........................................... 169 Table 4.22 Principal Eigenvalue calculation for sub-criteria of discourse .............. 169 Table 4.23 Weights of sub-criteria discourse obtained from AHP .......................... 169 Table 4.24 Pairwise comparison matrix for sub-criteria of participatory tools.........165 Table 4.25 Normalized matrix for sub-criteria of participatory tools ...................... 181 Table 4.26 Priority vector for sub-criteria of participatory tools...............................167 Table 4.27 Principal Eigenvalue calculation for sub-criteria of participatory tools 181 Table 4.28 Weights of Sub criteria discourse obtained from AHP .......................... 181 Table 4.29 Relative importance of criteria and the sub-criteria of the planning process ...................................................................................................................... 181 Table 5.1 Estimated flood damage ........................................................................... 181 Table 5.2 Role of stakeholders in flood risk management ....................................... 197 Table 5.3 Evaluation of existing approach for flood risk management ....................197 Table 5.4 Assessment of existing flood risk management practices in Panadura......206 Table 5.5 Rainfall analysis........................................................................................209 Table 5.6 Recommendations to improve the conceptualization of FRM in the present decision making ....................................................................................................... 217 Table 5.7 Recommendations to improve the assessment of FRM in the present decision making ....................................................................................................... 221 Table 5.8 Recommendations to improve the discourses related to FRM in the present decision making ........................................................................................... 225 Table 5.9 Review the existing governance tools of stakeholders of existing decision making of flood risk management ........................................................................... 231 xiv LIST OF APPENDICES Appendix A: Questions used for the development of the framework .................... 294 Appendix B: Questions used for calibration of the framework ................. .......... 320 Appendix C: Questions used for validation of framework . …………........... 322 Appendix D: Consensus development with the experts .......................................... 338 xv LIST OF ABBREVIATIONS Abbreviation Description AHP Analytic Hierarchy Process CBA Cost Benefit Analysis EAD Expected Annual Damage EPL Exceedance Probability-Loss FPGAS Flood Risk Governance Arrangements FRM Flood Risk Management FRMS Flood Risk Management Strategies NWSDB National Water Supply and Drainage Board SER Socio Ecological Resilience USD United States Dollar