An Evaluation of Coastal Flooding Risk Due to Storm Surge Under Future Sea Level Rise Scenarios in Thua Thien Hue Province, Vietnam
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An Evaluation of Coastal Flooding Risk due to Storm Surge under Future Sea Level Rise Scenarios in Thua Thien Hue Province, Vietnam by Thu Nguyen, PhD A Thesis In Geoscience Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Approved Dr. Jeffrey Lee Chair of Committee Dr. Katharine Hayhoe Dr. Cao Guofeng Dr. Kevin Mulligan Mark Sheridan Dean of the Graduate School December 2017 Copyright Page 2017, Thu Nguyen Texas Tech University, Thu Nguyen, December 2017 ACKNOWLEDGEMENTS The most important acknowledgement of gratitude I wish to express is to my committee chair, Dr. Jeff Lee at Department of Geosciences, who has the attitude and the substance of a genius. Dr. Lee has motivated me for this research and their constant guidance and supports. He granted me various conveniences without which it would not have been possible to do the work. I would like to express my profound appreciation to my adviser, Dr. Katharine Hayhoe at Department of Political Science, who inspired me this research. Dr. Hayhoe has put her immense knowledge, valuable experiences and wisdom at my disposal. I would like to thank my committee members, Dr. Cao Guofeng and Dr. Kevin Mulligan, for their practical advice in my research work and suggested many important addition and improvement. Special thanks to my dear friends, especially to Mr. Dien Xuan Nguyen in Vietnam, who provided me with the most important inputs including data, software and even training. Without his help and inputs this work would not have been done. And finally, I would like to say this thesis is dedicated to my husband and children who have always stood by me and support me unconditionally. Without their love, support and hardship over years none of this work would have been possible. They have always been there for me and I am thankful for everything they have helped me achieve. Thanks for all your encouragement! ii Texas Tech University, Thu Nguyen, December 2017 TABLE OF CONTENTS ACKNOWLEDGEMENTS ............................................................................................. ii ABSTRACT ........................................................................................................................v LIST OF TABLES ........................................................................................................... vi LIST OF FIGURES ........................................................................................................ vii MOTIVATION FOR THE WORK ............................................................................. viii CHAPTER ONE ............................................................................................................... 1 INTRODUCTION..............................................................................................................1 1. Background .......................................................................................................... 1 2. Climate Change in Vietnam ................................................................................. 3 2.1 Climate change scenarios ...................................................................................... 4 2.2 Sea level rise scenarios .......................................................................................... 7 2.3 Impacts of Climate Change ................................................................................. 10 3. Dissertation Objectives ......................................................................................12 CHAPTER TWO ............................................................................................................ 13 LITERATURE REVIEW ...............................................................................................13 1. Sea Level Rise .................................................................................................... 13 2. Tropical Storm/Storm Surge .............................................................................. 15 3. Land subsidence ................................................................................................. 16 4. Coastal Flooding ................................................................................................ 17 5. Vertical uncertainty in elevation-based SLR assessment ................................... 18 6. Reliability of MIKE 21 FM model in inundation modeling .............................. 20 7. Justification ........................................................................................................ 21 CHAPTER THREE ........................................................................................................ 23 STUDY AREA ..................................................................................................................23 1. Geographical Characteristics.............................................................................. 23 2. Disaster context and their impacts in Thua Thien Hue ...................................... 25 CHAPTER FOUR ........................................................................................................... 29 METHODOLOGY ................................................................................................................... 29 1. Data Sets and Pre-Processing ............................................................................. 30 iii Texas Tech University, Thu Nguyen, December 2017 1.1 Data sets for MIKE 21 FM modeling .................................................................. 31 1.2 Data source for impact analysis using ArcGIS tools ........................................... 33 2. Approach ............................................................................................................ 34 CHAPTER FIVE ............................................................................................................ 52 RESULTS .................................................................................................................................... 52 1. Simulation of coastal flooding ........................................................................... 52 2. Analysis of Impacts ............................................................................................ 52 CHAPTER SIX ............................................................................................................... 64 CONCLUSIONS ....................................................................................................................... 64 iv Texas Tech University, Thu Nguyen, December 2017 ABSTRACT This study attempts to quantify the impacts of coastal flooding on land area, population and urban infrastructure that would result from an extreme tropical storm occurring over a range of for future sea level rise scenarios. This case study follows a storm named Xangsane, that occurred in Thua Thien Hue, a central province in Vietnam, in 2006. It compares the impacts caused by different scenarios of storm surges and sea levels simulated on two different datasets, a national one and a global one. A 2-dimentional hydrodynamic model is used to simulate the storm surge and coastal flooding. The numerical simulation is coupled with ArcGIS tools to analyze the level and extent of inundation areas as well as their influences on population and urban infrastructure (transportation system, schools, hospitals, and historical heritage sites). Projection indicates that the sea level rise (SLR) of 1 m and 2 m can cause huge impacts for transportation infrastructure and buildings. The impact increase on transportation infrastructure is considerably significant, from 200% to 400% increase on all types of road across different storm surge scenarios. The impact on railroads is the least, about 32 km to 50 km in SLR of 1 m and 2 m, but its impact percentage is the highest among all other categories. The maximum railroad impact increases nearly 2000% for SLR of 1 m and 3500% for SLR of 2 m with or without storm surge. For land area, building (school and hospital), and special infrastructure, the impacts increase up to 450% in SLR of 1 m and 2 m simulated on both datasets (the national and the global). The risk of flooding is closely related to the SLR more than storm surges. The impact of projected sea levels increases the need for flood control measures in Thua Thien Hue province. v Texas Tech University, Thu Nguyen, December 2017 LIST OF TABLES Table 1: Relative frequency of natural disasters in Vietnam (CCFSC, 2005) ................................ 3 Table 2: Summary of original data and their sources .................................................................... 31 Table 3: Study Scenarios ............................................................................................................... 36 Table 4: Mesh Generation Parameter ............................................................................................ 38 Table 5: Parameters of the MIKE 21 flow model .......................................................................... 40 Table 6: Total inundated area (km2) in different scenarios ........................................................... 53 Table 7: Storm Making Land-falling_National Data 10K ............................................................. 54 Table 8: Storm Moving Along The Coast_National Data 10K...................................................... 55 Table 9: Storm Making Land-falling_Global Data SRTM ...........................................................