THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY NGUYEN NAM HAI APPLICATION GEOGRAPHIC INFORMATION SYSTEM IN ASSESSING FLASH FLOOD, NA RI DISTRICT, BAC KAN PROVINCE BACHELOR THESIS Study[.]
THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY NGUYEN NAM HAI APPLICATION GEOGRAPHIC INFORMATION SYSTEM IN ASSESSING FLASH FLOOD, NA RI DISTRICT, BAC KAN PROVINCE BACHELOR THESIS Study Mode: Full-time Major : Environmental Science and Management Faculty : Advanced Education Program Batch : 2015 - 2019 Thai Nguyen, 09/2019 Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Environmental Science and Management Student name Nguyen Nam Hai Student ID DTN 11554290008 Thesis title Supervisor Application geographic information system in assessing flash flood, Na Ri district, Bac Kan province Dr Nguyen Thanh Hai Supervisor’s signature Abstract: The purpose of this study is to develop a flash flood warning map in Na Ri district, Bac Kan province to provide data and maps about the high risk areas for flash floods This study analyzes factors such as soil, river, vegetation, etc in Na Ri district Na Ri is a hilly area with many rivers and soil being easily washed away due to forest exploitation activities or forest felling as a residence, floods, and landslides have continued in recent years Therefore, we need to develop maps that can warn the locals to help people pay attention to vulnerable areas and take precautions before the rainy season Keywords Flash flood, Na Ridistrict, Geographic Information System (GIS) Number of pages 39 Date of submission 07/09/2019 i ACKNOWLEDGEMENT I would like to express my gratitude to my supervisor Dr Nguyen Thanh Hai, MsC Nguyen Van Hieu, for his invaluable useful comments, remarks, encouragement and engagement through the learning process of this graduated thesis I sincerely thank the lecturers who enthusiastically imparted useful knowledge on flooding during the University program to all class attendants I also thank the support of Thai Nguyen University of Agriculture and Forestry, the coordinators and program managers for their support and assistance Finally, I would like to express our gratitude to the family, relatives and friends who have helped me during the internship Thank you very much! Nguyen Nam Hai ii TABLE OF CONTENT ACKNOWLEDGEMENT ii TABLE OF CONTENT iii LIST OF FIGURES LIST OF TABLES PART I INTRODUCTION 1.1 Research rationale 1.2 Research’s objectives 1.3 Research questions and hypotheses 1.4 Limitations PART II LITERATURE REVIEW 2.1 Flash floods 2.1.1 Definition 2.1.2 Classify 2.1.3 Factors causing flash floods 2.1.4 Basic characteristics of flash floods 2.1.5 The basic criteria for determining flash floods 2.2 Situation of flood in Vietnam and in the world 2.2.1 Situation of flood in the world 2.2.2 Situation of flood in Vietnam 11 2.3 Geographic Information System 13 2.3.1 Definition 13 2.3.2 Main factor in GIS 13 2.3.3 Function of GIS 13 iii 2.3.4 Ability to apply GIS in flash flood research and analysis 14 2.4 Na Ri district 15 2.4.1 Natural features 15 2.4.2 Topographic 16 2.4.3 Hydrological 17 PART III METHODS 20 3.1 Material 20 3.2 Methods 20 3.2.1 Most valuable of rainfall in a day 20 3.2.2 Map of surface slope 22 3.2.3 Map of land use 22 3.2.4 Map of distance on both sides of the river 23 3.2.5 Map of soil 23 3.3 Mapping process 24 PART IV RESULTS 27 4.1 Overlay the map layer 27 4.2 Commenting map 34 4.3 Proposing measures to prevent floods 34 PART V DISCUSSION AND CONCLUSION 36 5.1 Discussion 36 5.2 Conclusion 36 REFERENCE 38 iv LIST OF FIGURES Figure 2.1: Map of Na Ri district 16 Figure 3.1: Steps of mapping process 25 Figure 4.1: Raster calculator tool in GIS application 27 Figure 4.2: Map of Rainfall in Na Ri district 28 Figure 4.3: Map of slope in Na Ri district 29 Figure 4.4: Map of land use in Na Ri district 30 Figure 4.5: Map of distain on both sides of rivers in Na Ri district 31 Figure 4.6: Level of soil in Na Ri district 32 Figure 4.7: Map of area at risk of flash flood in Na Ri district 33 LIST OF TABLES Table 2.1 Rain threshold make flash flood Table 3.1: Classify and give points for the factor 26 PART I INTRODUCTION 1.1 Research rationale Flash floods is one of the natural disasters that happen unexpectedly, quickly and complicatedly, with great devastation in the mountainous areas that bring a lot of losses in people, economy and society.Climate change will cause unusual weather events that will accelerate floods and landslides Special, this phenomenon often occurs in the mountainous provinces, so losing due to natural disasters in general and flash floods in particular will increase many times compared to the delta regions.(Younis, J and J Thielen, 2008) Floods are formed by heavy rainfall, sweeping away everything on the surface of the flow, with great destructive power and destroying everything Floods are formed due to the synthesis of triggers such as topography, geomorphology, rainfall, vegetation cover, soil structure Combined with situation, that is increasing population and decreasing forest are due to deforestation in which many forests are concentrated in the watershed where the source of flash floods, from those areas to land for construction of houses, vacant land or agricultural land potentially soil retention, poor water retention and the construction of structures that prevent water flow With the growing of GIS, This can be forecast the number of rainfall, determine the actual state of coverage with data on topography, geomorphology, land properties are aggregated and by GIS tools to predict the areas at risk of natural disasters From all demand and benefit, with an agreement of leader of Thai Nguyen agriculture and forestry university, Geoinformatics research center, direct instructions from Msc Nguyen Van Hieu, Dr Nguyen Thanh Hai, I make a thesis: “Application geographic information system in assessing flash flood, Na Ri district, Bac Kan province.” 1.2 Research’s objectives - Using GIS for build map of damage of flood, rainfall, river or steam in Na Ri district, Bac Kan city - Assessment effect of flooding to nature and human - Forecast, warning the cures and building prevention method 1.3 Research questions and hypotheses - What is the overview of flooding in Na Ri district, Bac Kan city? - How can we determine all damage from flood? - How to use GIS application to build map? 1.4 Limitations - Because of geographic, it is difficult to make out area which damaged by flood - The Limited of vehicle to go to the flood area - There are too dangerous if we want to go to place that is flooding PART II LITERATURE REVIEW 2.1 Flash floods 2.1.1 Definition Flash floods are a large flood which is occurs unexpectedly and sustains for a short time, it has fast flow and great devastation and it can take all obstacles on the centralized flow of storage area.(Jonkman, 2005) 2.1.2.Classify Flash flood can be divided to three kind of flash flood dependent on the main reason: - Floods caused by local rain, concentrated in natural basins (almost no human impact) - Floods caused by heavy rains in the basins have been strongly affected by human economic activities (change of cover, flow regime or basin characteristics, ) - Flood caused by break dam or man-made lake 2.1.3 Factors causing flash floods There are three main factors: Factors with less change, factors with slow change and factors with fast change (Mai Thi Huyen, 2011) Those factors interact with each other and the extent of this impact on the type of basin to create different types of flash floods Therefore, determining the criteria for forming flash floods is to analyze the impact of this relationship for each specific basin - Factors with less change: topography, geology, geomorphology, soil,