Characterization of topographic surface and evaluation for flood hazard zonation in coastal lowland of danang city, vietnam

大阪市立大学大学院創造都市研究科 博士学位申請論文 CHARACTERIZATION OF TOPOGRAPHIC SURFACE AND EVALUATION FOR FLOOD HAZARD ZONATION IN COASTAL LOWLAND OF DANANG CITY, VIETNAM 2017 年 03 月 大阪市立大学大学院創造都市研究科 創造都市専攻創造都市研究領域 D13UD509 Tran, Thi An (トラン, テイ アン) ACKNOWLEDGMENT This thesis was completed under the kind assistances of number of people who I am in debt I would like to take this opportunity to express my gratitude to these people First of all, my deepest gratitude is sincerely to my supervisor - Prof Venkatesh Raghavan for his great supervision, support and continuous encouragement during my Ph.D course at Osaka City University His guidance always helped me in open-minded thinking and motivated me to be able to pursue my research interests I greatly appreciate him for patiently listening to me, understanding my weakness and strengthening me when I have any trouble in researching I learned from him not only research methods but also how to evaluate an issue, writing skills and also many moral guidance His advises were valuable not only for my study but also for my life in Japan He was more than a supervisor for me My sincere gratitude goes to Prof Shinji Masumoto, Graduate School of Science for his continuous support for me from the first day I entered this Osaka City University His immense knowledge and guidance helped me during my research study and he gently pointed me in the right direction when I had mistakes Thanks to his great support, I could pass over difficulties and finish my Ph.D course I would like to express my sincere thanks to Associate Prof Go Yonezawa and Associate Prof Daisuke Yoshida for their great support for me in Geoinformatics Lab I would like to thank them for giving me useful comments during seminar over last four years which were valuable for my research I wish to express my gratitude to Dr Susumu Nonogaki, Geological Survey of Japan for great support for me in DEM generation method He has given me the guidance in detail, the valuable comments and suggestions that helped me grow up in research His developed BS-Horzion program which was investigated in this study is one of the most important tools for the completion of this thesis Especially thanks to Prof Kiyoji Shiono, Japan Society of Geoinformatics for his kindly suggestions and corrections for the evaluation of parameters in BS-Horizon DEM generation My sincere thanks especially goes to my colleagues in Geoinformatics Lab for accompany with me during my course The discussion with them were always helpful for improving my study I also gratefully acknowledge Japanese Ministry of Education, Culture, Sport, Science and Technology for granting me Monbukagakusho - MEXT scholarship to enable me to study in Osaka City University Also I thank to Graduate School for Creative Cities for their facilities support for my research Besides, I would also thank to Danang Department of Natural Resource and Environment for providing field survey data which was very important in this research I would also like to thank The University of Danang, my professors as well as my colleagues in Faculty of Geography, University of Science and Education, The University of Danang for their support for me to study abroad Thanks also goes to all of my friends in Japan With memories of joy and help from them, I will never forget the great times we spent together Especially thanks to Ms Sachiko Raghavan for her kind help in everything during my life in Japan Last but not least, my unlimited thanks go to my beloved parents for their longdistance support and encouragement in every moment of my life, even though with lot of their difficulties Especially thanks to my little family, husband and my son for their great love and heartening me up in researching I could not finish my Ph.D without encouragement from my family Whatever I achieved is only to make them happy and proud TABLE OF CONTENTS Page ACKNOWLEDGMENTS LIST OF FIGURES LIST OF TABLES ABSTRACT i Chapter One: INTRODUCTION 1.1 Overview and motivation 1.2 Research objectives 1.3 Flood situations in Central Vietnam and Danang area 1.4 Review of related researches 1.5 Thesis outline Chapter 2: FUSION OF OPTICAL STEREO AND InSAR DERIVED GLOBAL DEMs 2.1 Introduction 2.2 Study area 2.3 DEM datasets 2.4 Fusion of optical stereo and InSAR derived DEM data 11 2.4.1 Pre-processing 11 2.4.2 DEM quality assessment 13 2.4.3 Minimizing DEM bias effect 14 2.4.4 DEM fusion algorithm 16 2.4.4.1 Weighted averaging 16 2.4.4.2 Filtering the noises for fused DEM 18 2.5 Accuracy assessment for fused DEM 19 2.6 Limitations of fused DEM 21 Chapter Three: GENERATION OF HIGH RESOLUTION DEM USING BS-HORIZON METHOD 22 3.1 Introduction 22 3.2 BS-Horizon theory 23 3.3 Data 25 3.4 Evaluating effects of parameter settings on the BS-Horizon DEM generation 26 Page 3.4.1 Equality and inequality constraints 26 3.4.2 Effect of M and α settings 28 3.4.2.1 M and α settings in case of using only equality constraints 28 3.4.2.2 Effects of M and α settings for equality-inequality constraint 30 3.4.3 Surface characteristics for different inequality constrained intervals 32 3.4.4 Evaluating effect of m1 and m2 settings 33 3.5 Discussion 35 3.5.1 Comparing BS-Horizon DEM generation from equality and equalityinequality constrained data 35 3.5.2 Selection of appropriate parameters for BS-Horizon DEM generation 36 3.6 BS-Horizon DEM assessment 37 Chapter Four: FLOOD HAZARD ZONATION USING MULTI-PARAMETRIC ANALYTICAL HIERARCHY PROCESS (AHP) 39 4.1 Introduction 39 4.2 Study area and data used 40 4.3 Methodology 41 4.3.1 Data preparation 41 4.3.1.1 DEM generation for study area 41 4.3.1.2 Flood inundation mapping from satellite image 42 4.3.2 Analytical Hierarchy Process (AHP) method 43 4.3.3 Causative parameters of flood 45 4.3.3.1 Elevation based flood inundation (EFI) 45 4.3.3.2 Distance from the river channel (DIST) 46 4.3.3.3 Topographic Wetness Index (TWI) 46 4.3.3.4 Land use (LU) 47 4.3.3.5 Slope 47 4.4 Results 48 4.4.1 Determining the weights for parameters of flood hazard 48 4.4.2 Flood hazard index (FHI) and flood hazard zonation 49 Chapter Five: DISCUSSIONS AND CONCLUSIONS 50 REFERENCES 54 LIST OF FIGURES Page Figure 2.1 Location of study area and topographic overview 62 Figure 2.2 Flowchart of data processing 62 Figure 2.3.Correlation between GDEM and Reference DEM before (left) and after (right) filling voids 63 Figure 2.4 Comparing stream networks of global DEMsandReference DEM before (up) and after (down) shifting DEM: (a) GDEM; (b) SRTM 63 Figure 2.5 Comparing GDEM and SRTM to Reference DEM: (a) before re-interpolation SRTM and shifting data; (b) after re-interpolation SRTM and shifting data 64 Figure 2.6 Correlation of GDEM and SRTM in flat (a) and mountainous (b) areas 65 Figure 2.7 A profile of GDEM and SRTM compare to Reference DEM in flat area 65 Figure 2.8 Difference elevation of GDEM and SRTM with respect to Reference DEM from mountain to flat area 66 Figure 2.9 Behaviour of GDEM and SRTM to Reference DEM in difference topographic contexts (a) Whole area; (b) A area; (c) B area; (d) C area; (e) D area 66 Figure 2.10 Landform classification map from SRTM 67 Figure 2.11 Weighted averaging used to fused global DEMs 68 Figure 2.12 Result of denoising algorithm (Sun et al 2007) on fused DEM 68 Figure 2.13 Correlation between fused DEM and Reference DEM 68 Figure 2.14 Difference in elevation between fused DEM and Reference DEM 69 Figure 2.15 Histogram from the difference elevation maps of SRTM, GDEM and Fused DEM (X axis: cell values in tens; Y axis: number of cells in thousands) 69 Figure 2.16: Slope (a), profile curvature (b) and tangential curvature (c) of fused DEM 70 Figure 2.17: Normal vector of topographic surface (a) and the angular difference between two normal vector (Hodgson and Gaile, 1999) 71 Figure 2.18 Limitations of Fused DEM compared to reference elevation data 71 Figure 3.1 Location of study area including field survey point elevation data (a) and Satellite RapidEye imagery in 2014 (b) of corresponding area 72 Figure 3.2 Distribution of field survey point elevation in study area based on different cases of M 73 Figure 3.3 Equality and inequality constraints used in surface estimations 73 Page Figure 3.4 Calculations of R( f ), J( f ) and the resulting Q( f ) in different cases of M and  when using equality constrained data 74 Figure 3.5 DEMs generated from equality constrained data using different M and  settings 75 Figure 3.6 Representation of R( f ), J( f ) and Q( f ) according to different M and α when using equality-inequality data 76 Figure 3.7 DEMs generated from equality-inequality constrained data using different M and  settings 77 Figure 3.8 Surfaces generated from equality constraints and equality-inequality constraints with R( f )