Identify the flood hazard index in the huong river basin hue city area

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 Thank you Hanoi, November 11th 2016 Vu Hoang Tung DECLARATION I hereby declare that is the research work by myself under the supervisions of Dr Pham Thanh Hai and Assoc Prof Dr 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 relevant 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 11th 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 local’s life and inhibits the socio-economic development of the city Therefore, in order to minimize losses of life and economic, a detailed and comprehensive flood hazard assessment 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, (iii) 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 B1, B2 and A1 scenarios Three flood components were considered, including flood depth, flood flows velocity and flood duration Flood maps were thenc 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 (A1), the high flood hazard zone covers 45.3% of the study area While the medium and low hazard zones covers 19.6% and 17.5%, respectively It is 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 CCFSC Central Committee for Flood and Storm Control AHP Analytical Hierarchy Process GIS Geographical Information System FHI Flood Hazard Index IPCC International Panel on Climate Change UNFCCC United Nations Framework Convention on Climate Change GDP Gross Domestic Product FDI Foreign Direct Investment WMO World Meteorological Organization DHI Danish Hydraulic Institute DEM Digital Elevation Model CBDRM Community-Based Disaster Risk Management ADPC Asia Disaster Preparedness Center TABLE OF CONTENTS CHAPTER I INTRODUCTION……………………………… .8 1.1 General introduction .8 1.2 Description of the study area 1.3 Description of the Huong River 10 1.4 Hue city in the context of climate change 11 1.5 Problems and need of study 18 1.6 Objectives of the study 21 1.7 Scope of study 21 CHAPTER II LITERATURE REVIEW………………………………………… 23 2.1 Flood hazard mapping 23 2.2 AHP method 25 2.3 Flood hazard index .27 CHAPTER III METHODOLOGY………………………………………………… 30 3.1 Conceptual framework 30 3.2 Overview of the research .31 3.3 Flood hazard mapping 31 3.4 Flood hazard index identification 37 CHAPTER IV DATA COLLECTION AND ANALYSIS………………………….44 4.1 Data collection .44 4.2 Data analysis 44 CHAPTER V RESULTS AND DISCUSSION…………………………………… 49 5.1 Hydrodynamic model parameters 49 5.2 Flood hazard mapping 57 5.3 Flood hazard index .61 5.4 The impacts of flood on Hue city in the contexts of climate change 62 5.5 Community-based disaster risk management (CBDRM) 71 CONCLUSION AND RECOMMENDATION…………………………………… 75 References…………………………………………………………………………… 78 LIST OF TABLES Table 1.1: Flood season in the Huong river 11 Table 1.2: The change of average temperature in the recent decades 13 Table 1.3: 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 rise in the future of Hue city (cm) 17 Table 3.1: Saaty Rating Scale 38 Table 3.2: Random inconsistency indices (RI) for different number of criteria 40 Table 4.1: Pairwise comparison of flood depth categories respect to flood hazard 47 Table 4.2: Pairwise comparison of flood duration categories respect to flood hazard 47 Table 4.3: Pairwise comparison of flood velocity categories respect to flood hazard 48 Table 4.4: Pairwise comparison of components respect to flood hazard 48 Table 5.1: Result of Mike21 FM calibration flood event in 1983 52 Table 5.2: Hydrodynamic parameters after calibration process 54 Table 5.3: Result of Mike21 FM verification, flood event in 1999 55 Table 5.4: Flooded area in districts in Hue City 58 Table 5.5: The change of flood depth between climate change scenarios with 64 Table 5.6: The change of flood hazard levels by area 70 Table 5.7: What community should and should not in each stage of flood management 73 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 12 Figure 1.3: Trend of average rainfall change in September – November .15 Figure 1.4: Trend of average rainfall change in July 15 Figure 1.5: The maximum daily rainfall in 10 past decades 16 Figure 1.6: Administration Map of Thua Thien Hue Province .22 Figure 2.1: Structure of FHI study methods 23 Figure 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 verification .35 Figure 3.5: Diagram for converting qualitative indexes to quantitative value 40 Figure 3.6: Applying AHP 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 51 Figure 5.3: Observed and Calculated discharge at Cross-section 53 Figure 5.4: Observed and Calculated discharge at Cross-section 53 Figure 5.5: Observed and Calculated discharge at Cross-section 54 Figure 5.6: Observed and Calculated discharge at Cross-section 55 Figure 5.7: Observed and Calculated discharge at Cross-section 56 Figure 5.8: Observed and Calculated discharge at Cross-section 56 Figure 5.9: Flood depth map at the Huong river – Hue city in 1999 57 Figure 5.10: Flood flows velocity map at the Huong river – Hue city in 1999 59 Figure 5.11: Flood duration map at the Huong river – Hue city in 1999 60 Figure 5.12: 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 64 Figure 5.14: The change of flood velocity in climate change scenarios .66 Figure 5.15: The change of flood duration in climate change scenarios .67 Figure 5.16: The change of flood hazard index in climate change scenarios .69 Figure 5.17: Disaster management cycle .72 CHAPTER I INTRODUCTION 1.1 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 (WRI), 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 million residents, and sunk and damaged more than 2,100 boats This flood caused damage worth US$364 million (CCFSC 2006) Being a coastal province in Central of Vietnam, Thua Thien Hue province has been suffering from floods impacts annually Especially, in the context of climate change, catastrophic floods are increasing 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 strictly One of the effective approaches which are being used widely in flood risk management is flood hazard assessment This approach showed its capacity 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 making decision Thus, realizing 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 result 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 1.2 Description 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°14'- 16°15' north, longitudes 107°02' - 108°11' east Area of the province is 5,053.990 km2; population is 1.115.523 people according to statistics in 2012 It borders Quang Tri 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 of lagoons and over 200,000 of forest The province comprises 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 area, 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 similar to Central Vietnam in general – a tropical monsoon climate In the plains and in the hills, the average annual temperature is 25oC, but in the mountains only 21oC (statistical yearbook 2004) The annual precipitation in the province is 3200 mm but there are important variations Depending on 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 0.9% of total sale of goods and services in the whole country This is compared with 12.7% of Hanoi and 23.5% of Ho Chi Minh City The province has more than 120 km of coastline, which provides for a seafood industry which produces over 40,000 tons/year consisting of over 500 species of fish Hue is the city of Thua Thien Hue province The city is the center of culture, politics, education, science, tourist… Area of the city is 71.68 km2 Population in 2012 is estimated as 344,581 people Hue city is located in downstream of the Huong River and Bo River, average height is about 3-4 m above sea level and is often submerged when a heavy rain occurs in the upstream of the Huong River 1.3 Description of the Huong River The Huong river basin is located from 15o29’ – 16o35’ of the North latitude to 105o07’-107o52’ of the East longitude, with the basin area of 2830 km2 The river length is 86.5km included 28 distributaries The upstream of the Huong River is called as Ta Trach River which derives from a high mountain area of Bach Ma mountain range The Ta Trach River connects with the Huu Trach River at the Tuan confluence From the Tuan confluence, the main flow is called the Huong River The river then flows in the general direction of southeast to northwest, passing the Hue city, and before flowing into the sea, the Huong River goes through the Tam Giang – Cau Hai lagoon Tam Giang - Cau Hai is the largest lagoon in the South East Asia, with an area of 22,000 ha, and a length of 68 km along the coastline of the province Finally, the river flows to the sea at the Thuan An and Tu Hien mouths Besides the Thuan An and Tu Hien estuaries, the lagoon systems have some smaller river mouths linking to the sea As same as other rivers in the Central of Vietnam, flood season in the Huong river basin is not so long, only about months: from September to December with the amount of water accounting for 70% - 75% of total volume of annual flow Therein, November has the largest amount of flood and often account for 30% - 35% of total volume of annual flow Although flood season is short but many large floods occurred 10 Flood velocity map at the Huong river – Flood velocity map at the Huong river – Hue Hue city with high emission scenario – A1 city with medium emission scenario – B2 in in 2030 2030 Figure 5.14: The change of flood velocity in climate change scenarios Based on flood velocity maps created for the flood in 1999 and assumed floods corresponding to climate change scenarios in 2030, the study found that the highest flood velocity (greater than 1m/s) still happens in the downstream in Phu hau district Flood velocity of 0.5 – m/s is mainly distributed in the riversides in Kim Long, Huong Long, Thuy Bieu districts However, the range of areas where have flood velocity of 0.5 – m/s tend to expand gradually through the scenarios B1, B2 and A1 Specifically, in B1, B2 and A1 scenarios, flood velocity of 0.5 – m/s appears in Thuan Hoa, Phu Thuan an a small part in the intersection area between Thuan Thanh and Tay Loc districts In Thuy Bieu district, in the flood velocity map in 1999, a large area of this district has flood velocity of 0.1 – 0.2 m/s However, in the B1 scenario, flood velocity appears in this district is mainly in 0.2 – 0.3 m/s And to the A1 scenario, the flood velocity calculated in most area of the district is 0.3 – 0.5 m/s Even the flood velocity greater than m/s also appears in this district in A1 scenario 66 Flood duration map at the Huong river – Hue city in 1999 Flood duration map at the Huong river – Hue city with low emission scenario - B1 in 2030 Flood duration map at the Huong river – Hue city with medium emission scenario – B2 in 2030 Flood duration map at the Huong river – Hue city with high emission scenario – A1 in 2030 Figure 5.15: The change of flood duration in climate change scenarios In flood duration map for the flood in 1999, the biggest flooding duration calculated is more than days, in small parts in Kim Long, Huong Long, An hoa, Tay Loc districts and riverside in Thuy Bieu district Most area of Hue city is flooded in the range of 2.5 days to days in the flood in 1999 In the low emission scenario B1, the flood duration greater than days tends to increase in the districts mentioned above Especially, in An Dong, Xuan Phu and Vi Da districts have flooded areas in more than days In B2 scenario, the areas submerged more than days are expanded significantly, accounting 67 for most area of Huong Long, An Dong, Xuan Phu and Kim Long districts Some areas in Tay Loc, Thuan Hoa, Phu Hiep, Vi Da districts are also flooded longer than days Besides, the areas flooded in - days are expanded in a very large area of Hue city Especially, the areas flooded in – days are increased considerably compared with it in 1999 In A1 scenario, most districts in the east of city including Vi Da, Xuan Phu, An Dong, Phu Hoi and Phu Nhuan are submerged more than days Especially, in An Dong district, almost the entire district is flooded more than days In Thuy Bieu district, most area of this district is also flooded in 4-5 days, instead of 2.5 – days in 1999 The area flooded more than days also accounts for a large area of this district Generally, most area of Hue city in A1 scenario is flooded more than days instead of 2.5 – days in 1999 The reason why this study area is submerged for a long time is because of sea water level rise at the downstream in the climate change scenarios The flood flow does not escape into the sea through the estuary, causing the long stagnation in the study area Flood Hazard Index map at the Huong river – Hue city in 1999 68 Flood Hazard Index map at the Huong river – Hue city with low emission scenario - B1 in 2030 Flood Hazard Index map at the Huong river – Flood Hazard Index map at the Huong river Hue city with medium emission scenario – B2 – Hue city with high emission scenario - A1 in 2030 in 2030 Figure 5.16: The change of flood hazard index in climate change scenarios From the results of flood hazard maps above, we found that, generally, the level of flood hazard in the districts in Hue city tends to increase gradually through the climate change scenarios compared with background scenario 1999 In the climate change scenarios, some areas in An Hoa, Huong So, Huong Long, the North of Tay Loc, Vinh Ninh, Phuoc Vinh, An Cuu, An Tay, Phuong Duc districts, and small areas in Thuan Thanh, Kim Long, Phu Hoi, Truong An districts are still in low level of flood hazard as background scenario 1999 because these areas have high topography Therefore, these locations are affected a little by the elements of flood However, some areas at low level of flood hazard is also narrowed gradually through low, medium and high emission scenarios Instead, the areas of medium flood hazard and high flood hazard expanded gradually Typically as An Hoa and Huong So districts, large areas at low level of hazard in 1999 are up to high level of hazard in A1 scenario In Thuy Bieu district, most of the area transfromed into medium level of hazard in B2 scenario and high level of hazard in A1 scenario In addition, most of the area of Thuan Loc district also switched completely from low level of hazard in 1999 to medium level of hazard in B2 and A1 scenarios The medium flood hazard areas which belong to Phu Hau, Phu Hiep, Tay Loc, Phu Cat, Vi Da, Phu Hoi, Xuan Phu, An Dong, Phu Nhuan, Vinh Ninh, Phuoc Vinh, An Cuu districts are also up to high level 69 of flood hazard in A1 scenario The change of flood hazard levels by area in climate change scenarios is calculated in table 5.6 Table 5.6: The change of flood hazard levels by area Scenario Historical B1 B2 A1 Year 1999 2030 2030 2030 Low Area (ha) 2116.3 2062.5 1596.5 1389.8 % 29.8 29.0 22.5 19.6 Medium High Area (ha) % Area (ha) 2577.5 36.3 1144.3 2453.3 34.6 1330.0 2365.5 33.3 18.9 1242.3 17.5 3219.8 % 16.1 18.7 26.6 45.3 If the city has no flood prevention measures and suitable planning in socio-economic development , floods will cause enormous damage about people and wealth for the Hue city in the future Irrefragable that over the years, flood is considered as the extremely dangerous disaster type with large intensity, fierce destruction causing annually losses for Thua Thien Hue Province in general and Hue city in particular That is reflected clearly through the recorded statistics about the loss of lives and economy after the floods Be aware of strong impacts of floods, Thua Thien Hue province had focused on investment for structural measures such as dyke systems, drainage systems in order to mitigate the effects of flood on local residents and socio – economic development Especially, in Hue city, many structural measures had been applied to protect the city from the impacts of floods However, in fact, in recent years, under the changes of climate and weather factors, floods are getting stronger and gradually beyond the control of the structural measures which had been built in the city Investing in building or upgrading flood control constructions may increase the ability to protect the city from floods in the short term However, this work requires a huge amount of money of the city annually Therefore, it can be said that the structural measures seem to be less effective in the present context The guidance and raising awareness to the people in order to enable them to prevent and mitigate the effects of floods by themselves is gradually proved to be more effective and get the attention of many researchers and managers at present Therefore, a new approach in flood risk management was established It called community based 70 flood risk management approach - an approach is being applied in many countries around the world, and in some regions in Vietnam Based on the flood hazard index maps the study has developed above, managers can fully determine the extent of the impacts of floods to every district in the city of Hue, which give appropriate guidance for local people in each specific area to assist them in mitigating the damage to people and property caused by floods in the most efficient way Community based flood risk management is totally fit and can be applied for the city of Hue in preventing and mitigating the risks caused by floods The study will introduce an overview of this approach and present how to apply this approach for flood risk prevention and mitigation in the city of Hue in the next section 5.5 Community-based disaster risk management (CBDRM) 5.5.1 Introduce to CBDRM Community based approaches have been applied by various community groups, national and international organizations and government departments for over two decades in South East Asian countries The importance of these approaches has been recognized through reducing local vulnerabilities In these approaches, the participation of community is considered as the heart of decision making and implementation of management activities The community is involved in the whole process, their felt and real needs as well as inherent resources are considered According to ADPC (2003), Community-based disaster risk management (CBDRM) is a process in which at risk communities are actively engaged in the identification, analysis, treatment, monitoring and evaluation of disaster risks in order to reduce their vulnerabilities and enhance their capacities This means capacities of local people are enhanced to help them assess the situation, identify risk reduction measures and implement them Risk reduction measures include mitigation and preparedness activities before a disaster occurs and response and recovery activities during and after the disaster as well In CBDRM approach, the involvement of community is always emphasized in all steps of disaster risk management 71 Figure 5.17: Disaster management cycle ` Source: (JANI, n.d.) 5.5.2 Importance of community in CBDRM The involvement of the community is important to ensure these values: - The information collected will be more relevant and will reflect the opinions and realities of community members, particularly the vulnerable and poor - The capacity (self-confidence, knowledge, skills like: team work, making plan, etc.) of the entire community to deal with hazards will be developed - Outsiders (experts, consultants, government officers, etc.) will understand better about community - Disaster management and community development activities and programs will achieve better, more practical and effective results - Community life will become more stable and sustainable 5.5.3 Responsibility of the local community for flood prevention and reduction in Hue city This section guides what community should and should not in each stage (before, during and after the flood) to minimize the negative impacts of floods for communities living along the river and dike With these instructions, communities can understand prevent harmful effects of flood 72 and implement measures to Table 5.7: What community should and should not in each stage of flood management Mitigation and preparedness       Develop a master plan for flood plain management Undertake local flood control measures (e.g channels, dykes, dams, flood-proofing, erosion control) Improve vegetation cover, e.g planting appropriate Vetiver grass/trees along river banks to prevent river erosion Set up local level flood detection warning system Establish a public awareness system Establish a village/commu ne emergency response team (trained in First Aid, search and rescue, early Relief and recovery Response Commune/village level Household level       Discuss and agree with your family members on what to when floods occur Identify where you can get help if someone in your family is injured during floods For example, local health workers, First Aid trained persons, etc Prepare bamboo/wood and ropes to make an attic area in your house to stay in Make sure that you can escape through a window, or through the roof, should the water level become too high Listen to the TV, radio or public loudspeakers for flood warnings Prepare an emergency bag (water proof) containing spare clothes, matches/lighters, drinking water, dry food, torch, important documents and other essential items; check the bag’s contents periodically to ensure that the items are always in good conditions and ready for use Protect your valuables and important documents (e.g land title, deeds, birth and/or marriage certificates)by putting them into a waterproof bag and store with the 73       Listen to the weather forecasts on the radio/TV to get up-to-date news on the flood situation Switch off the electricity supply to your house at the main source Move up to a preidentified high and safe place, for example, a twostorey building or a hill, when water rises to a preidentified level Watch out for snakes or other dangerous animals as they will also move to the higher ground Move the cattle/livestock to high ground along with sufficient fodder Don’t walk into water if you see that an electricity wire or post has fallen into the water or touch any electrical socket to prevent electrocution Don’t walk, wade, swim, ride a       Use mosquito nets when you sleep during the day and at night to prevent mosquito and insect bites (at all times) Don’t go to areas near riverbanks, or where there was landslide, or to where there are no people living Don’t enter any houses/buildin gs that have been flooded unless they are checked by the authorities Don’t touch any damp electrical sockets or turn on the electricity until everything is dry or has been checked Don’t use any food that soaked in floodwater Ask the Department of   warning, etc.) based on the villages/ commune Organize training in flood response, etc (as for typhoons)for community members Identify safe areas and make evacuation plans, ensure that people know where to evacuate to if necessary and how to get there       emergency bag, tools, equipment and enough food and water for at least one week in a dry, high safe place Strengthen your house to make sure that it can stand during floods Protect your house by putting sandbags around the house If your family has a boat,  make sure that it is well maintained and can be used when necessary Protect your water supply by covering your well and water containers, etc If it has been raining heavily for over 3hrs in a flash flood and landslide prone area, you should move to a pre-identified safe place Regularly clear and clean  drains and ditches During the flood season, boats should be kept ready at the river banks   74 motorbike or bicycle, play or work in flooded areas as you could be swept away and drown Even if the water is calm you could fall into a hole, as you cannot see it Wear a life jacket if you have one If not, you can use other things that float to hold onto, e.g inner tubes, big empty, plastic containers, or banana trees can be used as life buoys if you have to move into a flooded area Keep away from riverbanks or springs in the flooded areas as these may be undermined and may collapse Don’t drink floodwater Instead collect and use rainwater to drink and cook with Try always to boil the water If you have no alternative, use filtered or purified water (using water purification chemicals) Don’t eat spoiled food or food that was soaked in floodwater as there are a lot of bacteria in it and you could be      Health or Red Cross staff or to check the water quality and to clean your well before using it again Check and repair your home thoroughly if it has been flooded before returning Repair your latrine to make it safe (in terms of safety and hygiene) Seek medical help if you or any of your family members become ill Participate in cleaning up the environment in your area and around your house Plant Vetiver grass, bamboo or appropriate trees around your house and in public areas to stabilise soil and to protect it against floods infected and become ill CONCLUSION AND RECOMMENDATION The study has obtained some objectives: Studying flood hazard and its components in the Huong river basin - Hue city plays an important role in integrated flood risk management The Huong river basin in Thua Thien Hue province is a place where has usually been affected by floods Annually, in this basin, - storms happen with high intensity and the basin is usually submerged, that causes many loss of lives and economy, inhibits the socio-economy development of the region The study gave an overview of concepts and methodologies in flood hazard assessment via studies which have been done in the world Therefrom, study selected the approach of flood hazard index identification and flood hazard mapping to assess the flood hazard for the Huong river basin The study simulated the flooding process and created the flood depth, flood duration and flood velocity maps for the flood event in 1999 as well as the scenarios in the future by applying the 2D hydrodynamic model MIKE 21 and ArcGIS Use AHP method to weight the flood's components and apply the map overlapping method takes into account the weight of each component to generate the flood hazard map The study evaluated flood hazard level in the study area based on flood depth, flood velocity, flood duration and flood hazard index maps This approach is in line with economic capability and technical level and gives positive results The areas which have high level of flood hazard are Kim Long, Huong Long, An Hoa, Huong So, Vi Da, An Dong, Xuan Phu, Thuy Bieu districts These are lowland areas, accompanied with poor drainage system and fast-paced urbanization 75 The study also bases on sea level rise scenarios which calculated for Hue city to assess the changes of flood hazard in 2030 compared with the historical flood event in 1999 The results of study showed that if the government, city authority and local residents not have good preparation and response in flood risk management, the severe floods in the future will cause more damages to people and socio-economic development of the city Through assessing flood hazard, the study also introduce about a relatively new approach in flood risk management: Community based disaster risk management This approach has been applied in many countries, organizations and different regions in the world and it also demonstrated its capability through the results that it has brought in reducing flood risk for communities Based on these concepts, the study also gave some guides what community should and should not in each stage (before, during and after the flood) to minimize the negative impacts of floods These nonstructural measures are considered as simple, effective and completely suitable measures with conditions of study area Besides, the study gives some other recommendations: - Enhance the capability of flood early warning and forecasting in the study area by: upgrading and supplementing observation and monitoring system as well as communication and warning system in the whole of the study area - Organizing regularly the training sessions about strengthening the capability of coping with flood for managers and locals - Raising the awareness of local residents about the flood risk - Exchange the information and experiences in coping with flood among regions - Systematization and decentralization the management to ensure the planning, standard social economic infrastructure and residential areas in the flood prone areas in line with the standard of flood prevention in each region - Develop insurance fund for people and assets before the floods in order that households mitigate the consequences of flooding in affected area However, the limitations of this study: 76 - The topographic data is inadequate Therefore, the study selects the boundary of Hue city as the land boundary in Mike 21 model Therefore, the flood water was unable to spill over the boundary of the city This leads to the level of water depth calculated in this study is higher than in reality - Due to the lack of data in the stations, the data series for boundary conditions is extracted from the 1D model Mike 11 - The area of flooded regions which located in riversides calculated in the study includes a part of the Huong River - The selection for the flood components and the weight for each component should be based on the actual survey which collected from the local residents and consultation of experts in order to evaluate objectively these components in the AHP method - The study does not consider to the land cover, drainage capacity due to the lack of these data - Climate change is a complicated issue which includes changes of many factors However, due to the limitation in terms of time and knowledge, the flood simulation in climate change scenarios in the study was only based on Sea level rise scenarios without considering the changes of other factors 77 References ADPC (2003) CBDRM-11 course reference manual Asian Disaster Preparedness Centre, Bangkok Ajin, R S., Krishnamurthy, R R., Jayaprakash, M., & Vinod, P G (2013) Flood hazard assessment of Vamanapuram River Basin , Kerala , India : An approach using Remote Sensing & 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The result... calculate hazard index Flood hazard index map GIS Figure 3.6: Applying AHP in identifying flood hazard index at the Huong river – Hue city 42 Following the calculation of the weights, the FHI can... 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