Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. ASSESSING THE IMPACTS OF EXTREME FLOODS ON AGRICULTURE IN VIETNAM: QUANG NAM CASE STUDY A dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Environmental Management at Massey University, Manawatu, New Zealand. Vũ Ngọc Châu 2014 i Abstract Vietnam is situated within the tropical monsoon and typhoon zone of South-East Asia and is susceptible to extreme flood events. Since the most productive agricultural land is concentrated along the low-lying river systems, losses to agriculture resulting from extreme flooding can be significant. More than 70% of the country’s population live in rural areas, many in flood prone zones, and depend upon subsistence agriculture. However, to date, there have only been a limited number of studies addressing the impact of extreme flood events on agriculture in Vietnam. Using the Quang Nam province of central Vietnam as a case study, geographic information systems and digital elevation modeling are used to create geo- spatial inundation maps of flooded agricultural land. The mapped areas are populated with agricultural land use data and the direct costs of agricultural flood damage are calculated. Additionally, the institutional and legislative framework of Vietnam is assessed to determine whether there may be ways of streamlining systems and institutions to improve responses to extreme flooding events. This study shows that 1:10, 1:20 and 1:100-year flood events result in inundation levels of 27%, 31% and 33% of arable land respectively. The direct crop damage incurred in the inundated regions, expressed as a percentage of total value, are 12%, 56% and 62% respectively. The study also offers recommendations to improve flood management strategies. ii Acknowledgements This research journey was a challenging experience for me. I received my education from a passive learning system where students are told to do what their teachers require. However, in New Zealand, I was required to identify problems and I was responsible for solving problems under the guidance of my supervisors. At beginning, it was broad and I was so nervous. I read not only the literature on my research area, but also consulting the media for any pieces of information they broadcasted. I desired to contribute to natural disaster management in some way and to obtain skills that will enable me to assist with the issues facing my country both today and in the future. I am indebted to a number of people for their help with this thesis. Firstly, I wish to thank my supervisors Associate Professor John Holland and Dr Sue Cassells for their guidance and patience, and for what they have taught me, not only about science, but life. They were both consistently encouraging and supportive. In particular, I want to thank John, my big picture man for his intelligence, creative thoughts and endless enthusiasm. I’m grateful to Sue for not only her professional, relentless attention to detail and writing guidance, but also for what I learned from her as a role model outside of the academic discipline. I would not have completed this thesis without having them as my supervisors. Their help was appreciated more than they will know. I would also like to extend my gratitude to Mr Mike Tuohy who taught me the fundamentals of environmental GIS. My special thanks go to Matthew Irwin for his kind assistance throughout my GIS application in this study. Understanding GIS was a break-through step in my research journey. iii I am also grateful to the New Zealand ASEAN Scholar Awards for their funding which enabled this research to take place. I wish to thank the Vietnamese Ministry of Agriculture and Rural Development for its support of my study in New Zealand. I wish to express my appreciation to the Central Project Office, the Quang Nam’s Standing Office for Committee for Flood and Storm Control, the Department of Water Resource and the Agricultural Divisions of nine districts of Quang Nam province for data they provided and particularly for the field trip support. My appreciation goes to Massey University’s Institute of Agriculture and Environment, the International Student Support Office and the Centre for Teaching and Learning for their support and facilities for my study. Special thanks to Elizabeth Daly not only for her hours of proof-reading, but also for what I learned from her as a role model in modern society. I would like to extend my gratitude to Peter Lee, Fleur Hirst, Mike Christensen, Matt Krna, Sharon Wright, Jerry Teng, Melody Mendez, Nguyen Van Long and my friends at Massey University for their support, friendship and kindness. To everyone else who is not mentioned here, thank you very much for everything that you have done for me. It is not that you are unrecognised, but there are too many of you to mention. Without the support of you all, I would not feel happy as I do today. Finally, and most importantly, I would like to give all my deepest gratitude and respect to my family. To my parents and my passed away grandmother for their sentiments and faith in me. To my little family, Kim Lien, Tuan Kiet and Sarah for your understanding, encouragement and sacrifice throughout my journey. iv Abbreviations ADB Asian Development Bank B/C Benefit-cost ratio CBA Cost-Benefit Analysis CCFSC Central Committee for Flood and Storm Control CCFSCSR Commune Committee for Flood and Storm Control and Search and Rescue CRED Centre for Research on the Epidemiology of Disasters DARD Provincial Department of Agriculture and Rural Development DCFSCSR District Committee for Flood and Storm Control and Search and Rescue DEM Digital Elevation Model DMC Disaster Management Centre DMFSC Dyke Management and Flood and Storm Control Department DOF Provincial Department of Finance DONRE Department of Natural Resources and Environment DPI Provincial Department of Planning and Investment EVN Vietnam Electricity GDP Gross Domestic Product GIS Geographic Information System GSO General Statistical Office IDW Inverse Distance Weighting IPCC Intergovernmental Panel on Climate Change ISO International Organization for Standardization LNDPM Law on Natural Disaster Prevention and Mitigation MARD Ministry of Agriculture and Rural Development v MOD Ministry of Defence MOF Ministry of Finance MONRE Ministry of Natural Resources and Environment MPI Ministry of Planning and Investment NCSR National Committee for Search and Rescue OOG Office of Government PC People’s Committee PCFSCSR Provincial Committee for Flood and Storm Control and Search and Rescue pers.comm Personal communication UNDP United Nations Development Programme VND Vietnam Dong (Vietnamese currency) vi Table of Contents Abstract ................................................................................................................ i Acknowledgements ............................................................................................. ii Abbreviations ..................................................................................................... iv Table of Contents .............................................................................................. vi List of Tables ...................................................................................................... x List of Figures .................................................................................................... xi Chapter 1: Introduction ....................................................................................... 1 1.1 Background .......................................................................................... 2 1.2 Problem statement ............................................................................... 5 1.3 Aim and objectives ............................................................................... 6 1.4 Limitations ............................................................................................ 6 1.5 Contribution to research ....................................................................... 7 1.6 Thesis structure .................................................................................... 8 Chapter 2: Study area description .................................................................... 11 2.1 Introduction ......................................................................................... 12 2.2 Quang Nam agriculture ...................................................................... 16 2.3 Climate ............................................................................................... 18 2.4 Topography and river systems ........................................................... 19 2.5 Natural disasters in Quang Nam ........................................................ 20 2.6 Flooding in Quang Nam ...................................................................... 24 2.7 Conclusion .......................................................................................... 27 Chapter 3: Adapting GIS to map extreme floods in Vietnam ............................. 29 3.1 Introduction ......................................................................................... 31 3.2 Study area .......................................................................................... 36 vii 3.3 Data used ........................................................................................... 38 3.4 Method ............................................................................................... 42 3.5 Results ............................................................................................... 44 3.6 Discussion .......................................................................................... 49 3.7 Conclusion .......................................................................................... 52 Chapter 4: Calculating the cost of agricultural losses from flood events in central Vietnam .................................................................................................... 55 4.1 Introduction ......................................................................................... 57 4.2 Data used ........................................................................................... 65 4.3 Method ............................................................................................... 70 4.4 Results ............................................................................................... 79 4.4.1 Estimates of direct damage to agriculture .................................... 79 4.4.2 Scenario and sensitivity analyses ................................................ 82 4.5 Discussion .......................................................................................... 86 4.6 Conclusion .......................................................................................... 88 Chapter 5: Institutional structures underpinning flood management in Vietnam91 5.1 Introduction ......................................................................................... 93 5.2 Research approach ............................................................................ 95 5.3 Current legal documents pertaining to natural disaster management in Vietnam .................................................................................................... 96 5.4 Institutional structure for flood management ..................................... 100 5.5 Discussion ........................................................................................ 106 5.6 Recommendations ............................................................................ 110 5.7 Conclusion ........................................................................................ 112 Chapter 6: Strengthening flood management in the agriculture sector in Vietnam ............................................................................................................... 115 6.1 Introduction ....................................................................................... 117 6.2 Flood management in Quang Nam province .................................... 121 viii 6.2.1 GIS application in flood mapping ............................................... 126 6.2.2 Applied CBA in agricultural flood management ......................... 127 6.2.3 Implementation of flood management legislation ....................... 129 6.3 Discussion ........................................................................................ 130 6.4 Recommendations ........................................................................... 136 6.5 Conclusion ........................................................................................ 139 Chapter 7: Discussion ..................................................................................... 141 7.1 Introduction ....................................................................................... 142 7.2 Agricultural flood risk assessment .................................................... 144 7.3 The value of assessment tools in flood management ....................... 147 7.3.1 The value of GIS in flood management in Vietnam .................... 148 7.3.2 Valuing agricultural flood damage .............................................. 149 7.4 Potential measures and instrument options for flood risk treatment . 150 7.5 The relevance of this study to the LNDPM ....................................... 154 7.6. Conclusion ....................................................................................... 155 Chapter 8: Conclusion and recommendations ................................................ 157 8.1 Introduction ....................................................................................... 158 8.2 Research outcomes.......................................................................... 158 8.3 Recommendations ........................................................................... 159 8.3.1 Recommendations regarding leadership ................................... 160 8.3.2 Recommendations pertaining to technical data and research ... 160 8.3.3 Recommendations regarding economic analyses ..................... 161 8.3.4 Recommendations regarding institutional arrangements ........... 162 8.4 Recommendations for further research ............................................ 164 References ..................................................................................................... 167 Personal communication (pers.comm.)........................................................... 179 Appendix A: Inundation maps and agricultural land affected .......................... 181 ix Appendix B: Agricultural data .......................................................................... 184 Appendix C: Legal documents ........................................................................ 189 Appendix D: Research findings and recommendations for flood management ............................................................................................................... 193 Appendix E: Human ethics approval ............................................................... 199 x List of Tables Table 2.1. The most popular extreme events and affected level and location. . 22 Table 3.1. The flood frequencies calculated at the Cau Lau gauging station. ... 40 Table 3.2. Estimated areas of agricultural land in Quang Nam province affected by flood scenarios. ............................................................................................ 48 Table 4.1. Agricultural flood damage categories. .............................................. 62 Table 4.2. The predicted area (ha) of each crop affected at the four inundation levels for the three flood classes. ...................................................................... 74 Table 4.3. Susceptibility rates in yield (rice and corn) and replanted area (beans and vegetables) as a resulting of flooding (%). ................................................. 75 Table 4.4. The calendar for the main crop production and the flood seasons in Quang Nam province (2010). ............................................................................ 76 Table 4.5. Yields, economic benefits, costs and benefit-cost ratios for the major crops in the ‘without’ flood scenario (VND thousands, in 2010 prices). ............ 79 Table 4.6. The total damage (loss) to rice production (VND billion in 2010 prices) and the benefit-cost ratios for the three flood classes. .......................... 81 Table 4.7. Total loss of income for the four main crop types over the three flood classes (VND billion). ........................................................................................ 82 Table 4.8. Estimation of the total crop loss value (using 2010 yields) due to extreme flood events under pessimistic, likely and optimistic scenarios (VND billion in 2010 prices). ....................................................................................... 83 Table 4.9. B/C ratios for a 1:100-year flood as a result of simultaneous changes in product prices and either labour costs or, crop yields (for all crops). ............ 85 Table 7.1. Types of measures and instruments. ............................................. 151 xi List of Figures Figure 2.1. Population allocation and basic infrastructure of Quang Nam province. ........................................................................................................... 13 Figure 2.2. Contribution to GDP from agriculture, industrial and service sectors (1994 prices). .................................................................................................... 14 Figure 2.3. Sectorial contribution to GDP in Quang Nam province. .................. 15 Figure 2.4. Mixed maize and peanut farming in Quang Nam province. ............ 17 Figure 2.5. Cultivated crops along the Vu Gia-Thu Bon river bank. .................. 17 Figure 2.6. Spatial distribution of average annual rainfall in Quang Nam province. ........................................................................................................... 19 Figure 2.7. Casualties caused by natural disasters in Quang Nam province from 1997 to 2009. .................................................................................................... 21 Figure 2.8. Total damage caused by natural disasters from 1997 to 2009 in Quang Nam province (VND billion). .................................................................. 22 Figure 2.9. Spatial distribution of disaster types in Quang Nam province. ........ 23 Figure 2.10. Villages isolated and farms inundated by 2009 flood in Dien Ban district. .............................................................................................................. 26 Figure 2.11. National road No.1 at Duy Xuyen District inundated in the November 2007 flood (Photo: Vu Trung). ......................................................... 27 Figure 3.1. Global natural disasters. ................................................................. 31 Figure 3.2. The location and land use map of the Quang Nam province in central of Vietnam. ............................................................................................ 36 Figure 3.3. Six adjacent DEM tiles (a) from ASTER GDEM V2 were clipped to create the 30 metre resolution DEM of Quang Nam province (b). .................... 39 Figure 3.4. The location of the measured flood depth markers (left) and a typical flood depth marker (right) in the Vu Gia-Thu Bon river system. ........................ 41 Figure 3.5. The ArcGIS model created to automate processes for the output of land use maps affect by floods. ......................................................................... 43 Figure 3.6. Predicted inundation of Quang Nam province resulting from a 1:100- year flood event. ............................................................................................... 45 Figure 3.7. The predicted cumulative area of inundation in Quang Nam province resulting from the three flood scenarios. ........................................................... 46 xii Figure 3.8. Different land uses in Quang Nam province’s districts affected by the 1:100-year flood. ............................................................................................... 47 Figure 3.9. (a) 1:100-year flood map created by the Institute of Geography (2010) using hydraulic model MIKE11 GIS and (b) total areas of inundation in Quang Nam province. ....................................................................................... 49 Figure 4.1. Trends in rice production, yield/ha and total area for Vietnam (1980- 2010)................................................................................................................. 59 Figure 4.2. Predicted inundation of agricultural land in Quang Nam province, Vietnam, resulting from a 1:100-year flood event. ............................................ 66 Figure 4.3. Average annual rice yields/ha and trends in the ‘more’ flood-prone and ‘less’ flood-prone districts of Quang Nam province, 2000-2011. ................ 69 Figure 6.1. Inadequate capacity and maintenance of infrastructure amplifying flood damage in Quang Nam province............................................................ 121 Figure 6.2. Rating of both quantity and quality of items required for GIS, CBA applications and legal implementation on flood management. ........................ 125 Figure 7.1. The process of risk management. ................................................. 144 Figure 7.2. Flood risk analysis tool. ................................................................ 145