ACKNOWLEDGEMENT Firstly, I would like to express my sincere gratitude to my advisors Assoc. Hoang Thanh Tung and Dr. Pham Thanh Hai for the continuous support of my M. study and related research, for their patience, motivation, and immense knowledge.
Their guidance helped me in all the time of research and writing of this thesis. I could not have imagined having a better advisor and mentor for my M. Besides, I am especially grateful to lecturers in the Department of Hydrology and Water resources, Thuy Loi University and foreigner lectures from NICHE project who supported me for all the lectures and useful advices throughout my course. My sincere thanks also goes to my colleagues in National Hydro- Meteorological Service and Hydro-Meteorological Department of Middle Centre region who supported me for data collection and analysis.
Without they precious support it would not be possible to conduct this research. Last but not the least, I would like to thank my family: my parents, my wife and children for supporting me spiritually throughout the course and my life in general. 08" 2016 Nguyen Phu Luan ABSTRACT This study aimed at proposing solutions for managing large flood in Tra Bong river basin, Quang Ngai province, The research includes 2 main parts: create a flood inundation map based on historical flood marks collected and flood forecasting experiment for the downstream of river by simulating flood flow with the combination of hydrological and hydrodynamic models. At the first part, 42 flood marks of the 2009 historical flood had been collected with their exactly coordinate and maximum water level.
The distribution and elevation of flood marks have been used to calculate with topography data (DEM) using GIS tools and the result was the 2009 flood inundation map. At the second part, a rainfall ~ runoff hydrological model (NAM) has been firstly used to simulate flow from upstream of basin to the section at the beginning of the main river. The input data were collected from 3 rain gauge stations for simulation. After that, the computed water discharge got from rainfall-runoff ‘model have been used as the upstream boundary for simulating flood flow in the main river.
The model has been used was I-dimensional hydrodynamic model. After simulating the flood flow in the river, the study tried flood forecasting for the downstream part. Based on the flood inundation map and the result of flood forecasting experiment, the research has proposed solutions to manage large floods on Tra Bong river basin, These solutions can be used to develop large flood management plans for local authorities, in order to enhance efficiency in water resources using and reduce losses caused by large flood, Abbreviation cis Geographical Information System WMO World Meteorological Organization DH Danish Hydraulic Institute DEM Digital Elevation Model DMC Disaster Management Cycle MONRE Ministry of Natural Resources and Environment Moc Ministry of Construction NHMS National Hydro-Meteorological Sevice NAM ‘Nedbor-Afstromnings-Model (Danish, meaning rainfall-runolt model) IF Flood Foreeasting HD Hydrodynamic 1D, 2D 1-dimensiona BLE OF CONTENTS INTRODUCTION 1 General Introduction 2 Description of the Study Area 3 Problems and Need of Study. 4 Objectives of Study.
5 Scope of Study CHAPTER I: LITERATURE REVIEW 1.1 Related researches about study site 1.2 Flood inundation mapping, 1.3 Geographical Information Systems in Hydrology and Water Resources.4 Flood Forecasting (CHAPTER I: APPROACH AND METHODOLODY: 2.1 Approach of study 2.2 Flood inundation map 2.3 Using GIS tools to develop flood inundation map. 30 24 Mike 11 general description 32 2.5 Theoretical Foundation of rainfall - runoff hydrological model (NAM), 42 25.1 The ic parameters of NAM model 2.2 Basic modelling components 46 2.3 Initial conditions ofthe model 50 2.4 Model calibration sỉ 2.6 Flood Forecasting (Mike 11 FF): Updating procedure sỉ 2.1 Two unique features MIKE 11 FPS updating procedure 2.2 The calibration updating parameters 55 27 Flood Forecasting Error 37 (CHAPTER III: RESULTS AND DISCUSSIONS ” 3.1 Analysing flood features of Tra Bong river basin s 3.2 Develop flood inundation mapping for Tra Bong river basin.3 Flow forming simulation using Mi NAM m4 3.3 NAM model calibration and verifieation n 3.4 Flood flow in the downstream using Mike 11 hydraulic model $ 3.42 Calibration and verification of flood flow simulation model 84 3.5 Flood forecasting experiment for Tra Bong river system.6 Propose solutions oflarge flood managing in Tra Bong river basin 95 3.2 Nonestructure methods 9 CHAPTER IV: CONCLUSION AND RECOMMENDATION tô 4. 102 REFERENCES 103 LIST OF FIGURES Figure 1: Administration map of Quang Ngai Province 9 Figure 2.1: Structure of literature review.2: Conceptual framework for flood hazard and risk calculations.3: Different flood map types 20 Figure 2.4: Process for developing a flood forecasting model 25 Figure 3.1: Conceptual Framework 2 Figure 3.2: Overview of study.3: Digital Elevation Model with square grid 31 Figure 3.4: Error based on the topography data in flood inundation mapping 31 Figure 3.5: The structure of NAM model 38 Figure 3.6: Channel section with computational grid “ Figure 37: The shape of the computational grid around a node which has three branches 45 Figure 3.8: The shape ofthe grid points and the nodes in the complete modkl.9: Branch matrix before reducing 4 Figure 3.10: Branch matrix after reducing 47 Figure 3.11: Three-branch node with limit for continuity equation 48 Figure 3.12: River branch with discharge boundary 49 Figure 3.13: Illustration of amplitude and phase error.14: The updating results ofsimulations 35 Figure 3.15: Example of measured and simulated discharge at an update location .16: Example of updating parameters 31 Figure 4.1: Chart of the possibility of flooding which reach 2nd alarm level or higher in flood season - Tra Bong river basin, 6 Figure 4.2: 6 hour rainfall chart, from 19:00 27 Sep. 2009 - Tra Bong station 65 Figure 4.3: 6 hour rainfall chart, from 19:00 27 Sep.4: Hourly water level process of the flood from 28 Sep.
to 01 Oct, 2009 ~ Chau 0 station, 67 Figure 4.5: 2009 Flood marks map of Tra Bong river downstream 70 Figure 4.6: 2009 Flood inundation map of Tra Bong river basin.7: Map of hydro-meteorological stations network 4 Figure 4.8: Calculation layout T5 Figure 4.9: Weight factor distribution layout of rain gauge stations in Quang Ngai province.10: Basin parameters declaring dialog T¡ Figure 4.11: Parameters calibration for rainfall-runoff model (NAM), 7 Figure 4.12: Calculated flow process at Binh Minh station 8 Figure 4.13: Rainfall — runoff model (NAM) calibration, compare observed and ated flood discharge at Bình Minh ~ Tra Bong river, from 16 to 20 2008 $0 Figure 4.14: Rainfall - runoff model (NAM) calibration, compare observed and simulated flood discharge at Binh Minh - Tra Bong river, from 28 Sep to 5 Oct, 2009 $0 Figure 4.15: Rainfall = runoff model (NAM) calibration, compare observed and simulated flood discharge at Binh Minh ~ Tra Bong river, from 13 to 19 Nov, 2010.16: Rainfall — runoff model (NAM) verification, compare observed and simulated flood discharge at Binh Minh ~ Tra Bong river, from 14 to 20 Oct, 2011 81 Figure 4.17: Rainfall ~ runoff model (NAM) verification, compare observed and simulated flood discharge at Binh Minh ~ Tra Bong river, from 5 to 9 Nov, 201 82 Figure 4.18: Rainfall — runoff model (NAM) veri jon, compare observed and simulated flood discharge at Binh Minh — a Bong river, from 25 to 29 Nov, 2011 9 Figure 4.19: Hydraulic routing layout of Tra Bong river downstream 83 Figure 420: Initial conditions ealibration dialog $6 Figure 421: Bed resistance calibration dialog $6 Figure 4.22: Bed resistance calibration for cross-sections.23: MIKE 11 (HD) calibration, compare observed and simulated water level at Chau O station — Tra Bong river, from 16 to 20 Oct, 2008 88 Figure 4.24: MIKE 11 (HD) calibration, compare observed and simulated water level ‘at Chau O station ~ Tra Bong river, from 28 Sep to 5 Oct, 2009.25: MIKE 11 (HD) verification, compare observed and simulated water level at Chau O station — Tra Bong river, from 13 to 19 Nov, 2010.26: MIKE 11 (HD) verification, compare observed and simulated water level at Chau O station — Tra Bong river, from 14 to 20 Oct, 2011 90 Figure 4.27: Flood flow forecasting results from rainfall data at Binh Minh — The rains from 5 to 9 Nov, 2011 92 Figure 4.28: Observed and 5 hour predicted flood water level process in Chau O station - from 5 to 9 Nov, 2011 93 Figure 4.29: Flood flow forecasting results from rainfall data at Binh Minh — The rains from 25 to 29 Nov, 2011 93 Figure 4.30: Observed and 5 hour predicted flood water level process in Chau O station - from 25 to 29 Nov, 2011 9 Figure 5.1: Synthesis of large flood management solutions in Tra Bong river basin.2: Disaster Management Cycle 99 LIST OF TABLES Table 1.1; The morphological features of Tra Bong river and major tributaries.1; Overview of methods and data for high-resolution flood-tisk mapping in Germany.2: Predictive performance of the 3 models using independent calibration Jvalidation data 26 Table 3.1: Technical requirements of elevation different between the contours with corresponding scales 32 ‘Table 3.2: Quality of forecasting classification 59 ‘Table 4.1: Rainfall causes flood rising in Tra Bong river basin.2: Rainfall in the history flood on 28-30 Sep.3: Maximum daily rainfall in Tra Bong station, from 2006 to 2011 61 ‘Table 4.4: Annual peak flood of Chau O station (2006-2011) 2 Table 4.5: Typical flood intensity and amplitude in Chau O station (with the peak flood higher than first alarm level) @ ‘Table 4.6: The typical floods in 2006-2011 period of Chau O station.7: 6 hour rainfall data, from 19:00 27 Sep. 2009 ~ Tra n 65 acteristics of the flood from 28 to 30 Sep.9: The data of 2009 flood marks in Tra Bong river basin 67 ‘Table 4.10: The rain gauges used for hydrological calculating 75 Table 4.11: Results of parameters calibration for rainfall — runoff model 79 ‘Table 4.12: Results of NAM model calibration and verification at Bình Minh, 79 Table 4.13: Position of nod xin hydraulic calculation layout of Tra Bong river.14: Analysis of model calibration efficieney and error.15: Analysis of model verification efficiency and error 89 Table 4.16: Results synthesis of flood forecasting of Tra Bong river in Chau O station. 95 INTRODUCTION 1 General Introduetion Large flood is a kind of disaster occur regularly and seriously annually around the world. Flood has some benefits such as bring fertile soil to replace nutrient-poor soils, but it also impacts and causes enormous damage, constantly threatening people li ng and the economic and social development, People use many methods to prevent and reduce the impact of flood including management, structures and non-structures ‘methods.
Therein, large flood management is always an important objective, which requires detailed and specific research for each region, The research “Research on Large flood management of Tra Bong river basin, Quang Ngai province” aims at approaching a new point of view in flood management, in order to achieve high efficiency in reducing the harmful effects of flood to the economic development and environmental protection of study area. 2 Description of the Study Area Quang Ngai province is located at the latitudes 1432: 15°25' North, longitudes 108°06' - 109°04" East, lean on Truong Son mountain range, overlooking the Eastem ca. Quang Ngai abuts Quang fam province in the North, Binh Dinh province in the South, Kon Tum province in the West, and Eastem sea in the East. Located in the ‘middle of the country, it is 883km from Hanoi capital to Quang Ngai and 838km from Ho Chi Mink City.
Due to the steep topography and poor vegetation, so the transfer speed of flood is very high, flood’s damage is huge. Every year floods have caused extensive damage and losses of life and property. 600,000 people affected by flooding, especially some communes which suffered flood inundation elevation more than 3 m with the frequency of floods are 20% and 10%.