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University of Zimbabwe Tendai Nharo UNIVERSITY OF ZIMBABWE FACULTY OF ENGINEERING DEPARTMENT OF CIVIL ENGINEERING MODELING FLOODS IN THE MIDDLE ZAMBEZI BASIN USING REMOTE SENSING AND HYDROLOGICAL MODELING TECHNIQUES By TENDAI NHARO Supervisors Dr. Eng. H. MAKURIRA Mr. W. GUMINDOGA A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Water Resources Engineering and Management of the University of Zimbabwe JULY 2016 Declaration I Tendai Nharo, declare that this study work is my personal work and it is submitted in the department of Civil Engineering for the Master degree in Water Resource Engineering and Management. This information has not been submitted before for any degree of examination in any other University. Date Signature: Page | i Disclaimer This research was carried as part of the curriculum of study at the University of Zimbabwe, Civil Engineering Department. Opinions, views and expressions in this work remain the sole responsibility of the author, and not necessarily represent those of the University. Page | ii Table of Contents Declaration ....................................................................................................................................................... i Disclaimer ....................................................................................................................................................... ii List of Figures .................................................................................................................................................. v List of Tables .................................................................................................................................................. vi List of Equations ............................................................................................................................................vii Dedication .................................................................................................................................................... viii ACKNOWLEDGEMENT ............................................................................................................................... ix ABBREVIATIONS .......................................................................................................................................... x Abstract .......................................................................................................................................................... xi CHAPTER ONE: INTRODUCTION ................................................................................................................ 1 1.1 Background ..................................................................................................................................... 1 1.2 Problem Statement ........................................................................................................................... 3 1.3 Justification ..................................................................................................................................... 4 1.4 Objectives ....................................................................................................................................... 4 1.4.1 Main objective................................................................................................................................. 4 1.4.2 Specific Objectives .......................................................................................................................... 4 CHAPTER TWO: LITERATURE REVIEW .................................................................................................... 5 2.1 Introduction ............................................................................................................................................ 5 2.2 Analysis of floods ................................................................................................................................... 5 2.2.1 Flood dynamics on a global scale ..................................................................................................... 6 2.2.2 Floods in Southern Africa ................................................................................................................ 6 2.2.3 Floods in the Middle Zambezi River Basin ....................................................................................... 7 2.3 Factors affecting flood occurrence and magnitude ............................................................................ 8 2.3.1. Channel geometry and geology ....................................................................................................... 8 2.4 Methods to map and model floods........................................................................................................... 9 2.4.1. Remote Sensing in flood area delineation ...................................................................................... 10 2.4.2. Hydrologic flood modeling ........................................................................................................... 13 CHAPTER THREE: MATERIALS AND METHODS .................................................................................... 17 3.1 Description of study area ...................................................................................................................... 17 3.1.1 Climate ......................................................................................................................................... 17 3.1.2 Soils and Geology ......................................................................................................................... 18 3.1.3 Drainage........................................................................................................................................ 18 3.1.4 Socio –economic profile ................................................................................................................ 18 3.2 Methodology for flood inundated area analysis ..................................................................................... 19 3.2.1 Data acquisition ............................................................................................................................. 19 3.2.2 Validation of MODIS derived flooded areas ................................................................................... 19 3.3 Methodology for assessing factors affecting flood magnitude ................................................................ 20 3.3.1 Quantification of environmental factors ......................................................................................... 21 Page | iii 3.3.2 Generation of water and non-water random points .......................................................................... 24 3.3.3 Estimating Probability of flooding ................................................................................................. 25 3.3.4 Development of flood hazard maps ................................................................................................ 25 3.4 Methodology for flood mapping using hydrological and hydraulic modeling techniques ........................ 26 3.4.1 Hydrologic modelling through HEC-HMS ..................................................................................... 26 3.4.2 Flood routing through HEC-RAS ................................................................................................... 32 CHAPTER FOUR: RESULTS AND DISCUSSION ....................................................................................... 39 4.1 Variation of flood inundated areas ........................................................................................................ 39 4.1.1 Validation of MODIS derived flood areas ...................................................................................... 42 4.2 Factors affecting flood magnitude ......................................................................................................... 42 4.2.1 Environmental factors .................................................................................................................... 42 4.2.2 Flooding condition and environmental variables ............................................................................. 44 4.3 Hydrological modeling for flood mapping in the Mbire District. ............................................................ 47 4.3.1 HEC-HMS Model Calibration and Validation ................................................................................ 47 4.3.2 HEC-RAS flood routing ................................................................................................................ 52 CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS............................................................... 59 6.0 References ................................................................................................................................................ 62 7.0 Appendices ............................................................................................................................................... 68 Appendix A: MODIS DERIVED FLOODS .................................................................................................... 68 Appendix B: FACTORS AFFECTING FLOODS ........................................................................................... 69 Appendix C: HEC-HMS SIMULATIONS .....................................................................................................
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