ACKNOWLEDGEMENT I am indebted to my respected Advisors, Dr. Pham Thanh Hai and Ass - Prof. Hoang Thanh Tung who work as lecturers in Department of Hydrology and Water resources in Thuy Loi University for their continuous guidance, advice and expedience from the proposal preparation to thesis finalization. Their constructive comments, untiring help, guidance and practical suggestions inspired me to accomplish this work successfully.
Besides, I am especially grateful to other lecturers in the Department of Hydrology and Water resources who supported me in terms of the data collection and gave me useful advices for my thesis. I remember all those who have contributed directly or indirectly to successfully completing my study. Finally, I must express my very profound gratitude to my family for providing me with unfailing support and continuous encouragement throughout my years of study and through the process of researching and writing this thesis. This accomplishment would not have been possible without them.
Hanoi, November 11" 2016 Vu Hoang Tung DECLARATION Thereby declare that is the research work by myself under the supervisions of Dr, Pham Thanh Hai and Assoc. Hoang Thanh Tung. The results and conclusions Of the thesis are fidelity, which are not copied from any sources and any forms. The reference documents rel int sources, the thesis has cited and recorded as prescribed, “The results of my thesis have not been published by me to any courses or any awards.
Ha Noi, November 11" 2016 Vu Hoang Tung ABSTRACT Flooding is one of the major natural hazards in the city of Hue. This city is frequently affected by flooding and most of the low-lying areas in the city are flood-prone areas, Annually, the losses of people and property caused by flooding in Hue city are very much. This has a great influence on the loeal's life and inhi the socio-economic development of the city. Therefore, in order to minimize losses of life and economic, a detailed and comprehensive flood hazard asses went is necessary for both flood control and mitigation works, The objectives of this research were (i) to simulate flood flow in the city by using 2D hydrodynamic model MIKE 21 FM, (ii) to develop a hierarchical structure through the analytic hierarchy process (AHP) to define and qualify parameters that contribute to flood hazard, (ii) to map the flood components using the geographic information system (GIS), and (iv) to integrate these three methodologies and apply them to the Huong river basin in the Hue city to create flood hazard index map.
In addition, based on the sea level rise scenarios for Hue city in 2030, this study also calculated and created flood hazard index maps corresponding to BI, B2 and AI scenarios. Three flood components were considered. including flood depth, flood flows velocity and flood duration. Flood maps were thene drawn based on the data collected from institutes, inheriting the results of studies in the past, and documents related to historical flood events, climate change in Hue city.
The results show that high level of flood hazard tends to broaden over the low, medium and high emission scenarios. In the high emission scenario (AI), the high flood hazard zone covers 45.3% of the study area, While the medium and low hazard zones covers 19. Its concluded that integration of hydrodynamic model, AHP and GIS in flood hazard assessment can provide useful detailed information for flood risk assessment, and the method can be easily applied to other areas where necessary data is readily available Abbreviation wri World Resources Institute GDP Gross Domestic Production CCESC Central Committee for Flood and Storm Control AHP Analytical Hierarchy Process Gis Geographical Information System FHI Flood Hazard Index IPCC Intemational Panel on Climate Change UNFCCC United Nations Framework Convention on Climate Change GDP Gross Domestic Product FDI Foreign Direct Investment World Meteorol al Organization Danish Hydraulic Institute DEM Digital Elevation Model BDRM ‘Community-Based Disaster Risk Management ADPC Asia Disaster Preparedness Center TABLE OF CONTENTS CHAPTER I INTRODUCTION.2 Description ofthe study area 9 1.3 Deseription of the Huong River 10 1.4 Hue city in the context of climate change.5 Problems and need of study 18 1.6 Objectives of the study 21 1.7 Scope of study 21 CHAPTER II LITERATURE REVIEW.1 Flood hazard mapping.3 Flood hazard index.2 Overview of the research 31 3.3 Flood hazard mapping, 31 3.4 Flood hazard index identification 37 CHAPTER IV DATA COLLECTION AND ANALLYSIS.2 Data analysis 4 CHAPTER V RESULTS AND DISCUSSION, 5.1 Hydrodynamic model parameters 5.2 Flood hazard mapping.3 Flood hazard index.4 The impacts of flood on Hue city in the contexts of climate change.5 Community-based disaster risk management (CBDRM) m LIST OF TABLES ‘Table 1.1: Flood season in the Huong river " Table 1.2: The change of average temperature in the recent decades.3: Scenario of temperature change in future in Hue 13 Table 1.4: Scenario of rainfall change in future in Hue city 17 ‘Table 1.5: Scenarios of sea level ris in the future of Hue city (em) 17 Table 3.1: Saaty Rating Scale 38 ‘Table 3.2: Random inconsistency indices (RI) for different number ofcriteria 40 Table 4.1; Pairwise comparison of flood depth categories respect to flood hazard, 47 ‘Table 4.2: Pairwise comparison of flood duration categori respect to flood hazard 47 ‘Table 4.3: Pairwise comparison of flood velocity categories res pect to flood hazard.4: Pairwise comparison of components respect to flood hazard 48 ‘Table 5.1: Result of Mike21 FM calibration flood event in 1983.2: Hydrodynamic parameters after calibration process.3: Result of Mike21 FM verification, flood event in 1999 5s Table 5.4: Flooded area in districts in Hue City.5: The change of flood depth between climate change scenarios with.6: The change of flood hazard levels by area 70 Table 5.7: What community should do and should not do in each stage of flood management. B 6 LIST OF FIGURES Figure 1.1: Trend of average temperature in July (1986-2006) 12 Figure 1.2: Trend of average annual temperature in period 1986-2006.3: Trend of average rainfall change in September~ November 15 Figure 1.4: Trend of average rainfall change in July Is Figure 1.5: The maximum daily rainfall in 10 past decades 16 Figure 1.6: Administration Map of Thua Thien Hue Province 2 Figure 2.1: Structure of FHI study methods, 23 igure 3.1: Framework for flood risk assessment and risk management 30 Figure 3.2: Overview of the research 31 Figure 3.3: Study area 34 Figure 3.4: Steps for model calibration and verifi 35 Figure 3.5: Diagram for convert ualitative indexes to quantitative value.6: Applying AMP in identifying flood hazard index at the Huong river 42 Figure 4.1: Surface topography of the study area 45 Figure 5.1: Topographic Mesh 50 Figure 5.2: Checking cross-sections.3: Observed and Calculated discharge at Cross-section 1 3 igure 5.4: Observed and Calculated discharge at Cross-section2 53 Figure 5.5: Observed and Calculated discharge at Cro 34 Figure 5.6: Observed and Calculated discharge at Cross: 55 Figure 5.7: Observed and Calculated discharge at Cross: 56 Figure 5.8: Observed and Calculated discharge at Cross: 56 Figure 5.9: Flood depth map at the Huong river ~ Hue city in 1999 5 Figure 5.10: Flood flows velocity map at the Huong river~ Hue city in 1999.11: Flood duration map at the Huong river Hue city in 1999.12: Flood Hazard Index map at the Huong river ~ Hue city in 1999 61 Figure 5.13: The change of flood depth in climate change scenarios.14: The change of flood velocity in climate change scenarios 66 Figure 5.15: The change of flood duration in climate change scenarios.16: The change of flood hazard index in climate change scenarios 69 Figure 5.17: Disaster management cycle.1 General introduction ‘Over the last decades, flood has become a real threat that human have to face due to its severe impacts on economy, society and people.
According to the World Resources Institute (WRD, 20.7 million people are affected by river flooding each year, 56% of people at risk of being impacted by river flooding live in three countries: India, Bangladesh, and China. These combined with the next 12 largest impacted populations ~ in Vietnam, Pakistan, Indonesia, Egypt, Myanmar, Afghanistan, Nigeria, Brazil, ‘Thailand, Democratic Republic of Congo, Iraq, and Cambodia - account for 80% of the people at risk world-wide. In addition, an average of $96 billion in global Gross Domestic Product (GDP) is exposed to river flooding each year. And these numbers are expected to increase gradually in the next years because of population growth, ‘urbanization, and climate change.
As a result, it will increasingly put people at risk Floods in Viet Nam are well-known phenomena and occur in all regions of the country, especially in the Central Coast region (CCFSC 2006). As an example, the Central Viet Nam’s flood of November 1999 killed 780 people, affected around 1 million residents, and sunk and damaged more than 2. This flood caused damage worth US§364 million (CCFSC 2006). Being a coastal provinee in Central of ‘Vietnam, Thua Thien Hue province has been suffering from floods impacts annually.
Especially, in the context of climate change, catastrophic floo Sare in sing in term of frequency and magnitude, and taking a high death toll, assets and infrastructures. ‘Therefore, the measures in flood risk management and mitigation for Thua Thien Hue province are very indispensable and need to be researched siietly, One of the effective approaches which are being used widely in flood risk management is flood hazard as sment. This approach showed its cap: ity to apply in practice and it is a useful tool to facilitate in flood risk management and mitigation. Flood hazard assessment in a river basin can be performed by overlaying maps or/and identify indexes.
Each certain area has a hazard value. The value can be utilized in analyzing, estimating and comparing among different areas in order to support for 1g the impacts of floods on Thua Thien Hue province in general and Hue city in particular, this research studies “Identify the flood hazard index in the Huong river basin ~ Hue city area”. The sult of this project will be foundation for identifying the flood risk index and evaluating flood risk in the area, and support to help decision makers in making flood prevention plans for Hue city.2 Deseription of the study area ‘Thua Thien Hue is a province in the North Central Coast region of Vietnam. The province is located at the latitudes 16°1 ‘16°15! north, longitudes 107°02' - 108°11 cast, Area of the province is 5.990 km2; population is 1.523 people according to statistics in 2012.
It borders Quang xi province to the North and Da Nang to the South, Laos to the West and the East Sea to the East. The province has 128 km of coastline, 22,000 ha of lagoons and over 200,000 ha of forest. The province comprises 4 different zones: a mountainous area, hills, plains and lagoons separated from the sea by sandbanks. The mountains, covering more than half of the total surface of province, with height ranges from 500 to 1480 m.
The hills are lower, between 20 to 200 m, and ‘occupy about a third of the province's arca, between the mountains and the plains. The plains account for about a tenth of the surface area, with a height of only up to 20m above sea level. Between the hills are the lagoons which occupy the remaining 5% of the province's surface area ‘The climate in Thua Thien Hue province is lar to Central Vietnam in general ~ a tropical monsoon climate. In the plains and in the hills, the average annual temperature is 25°C, but in the mountains only 21°C (statistical yearbook 2004), The annual precipitation in the province is 3200 mm but there are important variations.
Depending fon the year, the annual average may be 2500 to 3500 mm in the plains and 3000 to 4500 mm in the mountains, In some years the rainfall may be much higher and reach more than 500 mm in the mountains. “The sale of goods and services in the province is 10930.6 billion VND accounting for 0.