ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES DEPARTMENT OF EARTH SCIENCES APPLICATION OF GIS AND REMOTE SENSING FOR FLOOD HAZARD AND RISK ANALYSIS: THE CASE OF BOYO CATCHMENT. Destaye Gobena June, 2009 ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES DEPARTMENT OF EARTH SCIENCES APPLICATION OF GIS AND REMOTE SENSING FOR FLOOD HAZARD AND RISK ANALYSIS: THE CASE OF BOYO CATCHMENT. Destaye Gobena A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in the Partial Fulfillment of the Requirements for the Degree of Masters of Science in GIS and Remote Sensing ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES DEPARTMENT OF EARTH SCIENCES APPLICATION OF GIS AND REMOTE SENSING FOR FLOOD HAZARD AND RISK ANALYSIS: THE CASE OF BOYO CATCHMENT. Destaye Gobena APPROVED BY EXAMINING BOARD: SIGNATURE Balemwal Atnafu (Ph.D.) ______________________________ Chairman, Department Graduate Committee K.V. Suryabhagavan (Ph.D.) ______________________________ Advisor Mekuriya Argaw (Ph.D.) ______________________________ Examiner Balemwal Atnafu (Ph.D.) ______________________________ Examiner ii Acknowledgement The achievement of this paper has come through the overwhelming help of many people. I wish to express my sincere gratitude to all those who offered their kind corporation and guidance throughout my project period. First and for most, I would like to thank Jesus for his provisions, protections and support in my entire life. I would like to convey my sincere gratitude to my advisor Dr. K.V. Suryabhagavan for his guidance and constant encouragement. My deeper gratitude goes to my advisor, Prof. M. Balkrishnan who patiently corrected the manuscript and provided me valuable comments. I remain indebted to the Addis Ababa university community in general and the Department of Earth Sciences staff in particular for their cooperation during my stay in this campus. Particular thanks go to Dr. Dagnachew Legesse, Dr. Tenalem Ayenew and Dr. Mohammed Umer. I also thank my family especially my sister, Selam Gobena for supporting me without whom this work would not have been completed. I am highly indebted to my mother, W/ro Meseret Dejene for her blessings and encouragment. My thanks are also extended to my beloved friend Tsegaye Abera for his invaluable coorporation, encouragment and support during the courses without whom this work would not have been completed. Least but not last, I would like to convey special thanks to my friends Sintayehu, Emun, Mesi Azeb, Mery and all GIS department students for sharing unforgettable time during my stay in campus. iii Table of Contents 1 INTRODUCTION ................................................................................................................... 1 1.1 Background ....................................................................................................................... 1 1.2 Problem Statement ............................................................................................................ 2 1.3 Research Objectives ......................................................................................................... 3 1.3.1 General Objectives .................................................................................................... 3 1.3.2 Specific Objectives .................................................................................................... 3 2 Literature Review .................................................................................................................... 4 2.1.1 Flood risk and hazard management ........................................................................... 4 2.1.2 Effect of Flood: Global, National and Regional perspective .................................... 4 2.1.3 Application of Remote Sensing and GIS for Flood Hazard Assessment .................. 6 2.1.4 A Decision Support System for Flood Disaster Management .................................. 8 2.1.5 Flood problem in Ethiopia ....................................................................................... 10 2.1.6 Previous Work ......................................................................................................... 12 3 Materials and Methods .......................................................................................................... 13 3.1.1 Materials .................................................................................................................. 13 3.1.2 Methods ................................................................................................................... 13 3.2 Study Area Description .................................................................................................. 15 3.2.1 Location ................................................................................................................... 15 3.3 Geology .......................................................................................................................... 16 3.3.1 Regional Geology .................................................................................................... 16 3.3.2 Local Geology ......................................................................................................... 20 3.3.3 Geologic Structures in the Study Area .................................................................... 21 3.4 Geomorphology .............................................................................................................. 21 3.5 Soil .................................................................................................................................. 23 3.6 Drainage .......................................................................................................................... 23 3.6.1 River System ........................................................................................................... 25 3.7 Climate ............................................................................................................................ 25 3.7.1 Rainfall .................................................................................................................... 26 3.7.2 Temperature ............................................................................................................ 26 3.8 Physiography .................................................................................................................. 27 3.9 Population and settlement ............................................................................................... 27 3.10 Flood problem in the study area .................................................................................. 29 3.10.1 Flood Protection Mechanisms in the Study Area .................................................... 31 4 Data Analysis ........................................................................................................................ 32 4.1 Research Geodatabase Design ........................................................................................ 34 4.2 Factors governing Flood Hazard in the study area ......................................................... 35 4.2.1.1 Slop factor ........................................................................................................ 35 4.2.1.2 Drainage Density Factor .................................................................................. 36 4.2.1.3 Elevation factor ................................................................................................ 37 4.2.1.4 Land use Factor ................................................................................................ 38 i 4.2.1.5 Rainfall Factor ................................................................................................. 39 4.2.1.6 Geomorphology Factor .................................................................................... 42 4.2.2 Flood Hazard Analysis ............................................................................................ 43 4.2.3 Flood Risk Analysis ................................................................................................ 45 4.2.4 Flood related with seasonal expansion of Lake Boyo ............................................. 45 5 Results and Discussion .......................................................................................................... 48 5.1 Flood Hazard .................................................................................................................. 48 5.2 Flood Risk ....................................................................................................................... 50 5.2.1 Land use/Land cover Change and Flood Hazard/Flood Risk ................................. 52 5.3 LULC in 1984 ................................................................................................................. 52 5.4 LULC in 2005 ................................................................................................................. 54 5.5 Change Detection ........................................................................................................... 55 6 Conclusion and Recommendation ......................................................................................... 57 6.1 Conclusion ...................................................................................................................... 57 6.2 Recommendation ...........................................................................................................