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Hydrological Response to Land Cover and Management (1935-2014) in a Semi-Arid Mountainous Catchment of Northern Ethiopia

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Hydrological Response to Land Cover and Management (1935-2014) in a Semi-Arid Mountainous Catchment of Northern Ethiopia i Copyright: Etefa Guyassa 2017 Published by Department of Geography – Ghent University Krijgslaan 281 (S8), 9000 Gent (Belgium) © All rights reserved iii Faculty of Science Etefa Guyassa Hydrological response to land cover and management (1935-2014) in a semi-arid mountainous catchment of northern Ethiopia Proefschrift voorgelegd tot het behalen van de graad van Doctor in de Wetenschappen: Geografie 2016-2017 v Cover: view of Mekelle. Black and white photograph (1935) by © Istituto Luce Cinecittà vii Promoter Prof. dr. Jan Nyssen, Ghent University Co-promoters Prof. dr. Jean Poesen, Division of Geography and Tourism, Faculty of Sciences, KU Leuven, Belgium Dr. Amaury Frankl, Department of Geography, Faculty of Sciences, Ghent University, Belgium Member of the Jury Prof. Dr. Ben Derudder, Department of Geography, Faculty of Sciences, Ghent University, Belgium (chair) Prof. Dr. Veerle Van Eetvelde, Department of Geography, Faculty of Sciences, Ghent University, Belgium Prof. Dr. Matthias Vanmaercke, Department of Geography, Faculty of Sciences, University of Liege, Belgium Prof. Dr. Charles Bielders, Earth and Life Institute, Faculty of Biosciences Engineering, Université Catholique de Louvain, Belgium Prof. Dr. Rudi Goossens, Department of Geography, Faculty of Sciences, Ghent University, Belgium Prof. Dr. Sil Lanckriet, Department of Geography, Faculty of Sciences, Ghent University, Belgium Dean Prof. dr. Herwig Dejonghe Rector Prof. dr. Anne De Paepe ix Scientific citation: Scientific citation: Etefa Guyassa, 2017. Hydrological response to land cover and management (1935-2014) in a semi-mountainous catchment of northern Ethiopia. PhD thesis. Department of Geography, Ghent University, Belgium. xi Acknowledgements It is my pleasure to acknowledge several people and organizations for their contribution to this study. First of all, I express my sincere gratitude to my promoter Prof. Dr. Jan Nyssen, for his tireless support during both the field work in Ethiopia and during the office work in Belgium. During my study period I have received from him an indispensable advice, many comments and suggestions and answers to my questions. His guidance and supervision during proposal writing, research undertaking and thesis writing was astonishing. I also would like to express my deepest appreciation to my co-promoter Dr. Amaury Frankl, for his unlimited support both in field work in Ethiopia and advice in Belgium. I am very grateful to Prof. Dr. Jean Poesen, also my co-promoter, for his unreserved comments and suggestions, which boosted my thesis to higher standard. Special appreciation also goes to Dr. Miro Jacob for his countless support during my thesis write up. Moreover, this study would not have been possible without the kindly support of Mr. Seifu Gebresilase who was facilitating the field works around Hagere Selam, through his friendly communication with local government and farmers. My great appreciation extends to farmers for letting us work in their village and fields for our field experiments. Additionally, I would like to thank Mr. Gebremeskel Kiros and Mr. Hailay Tesfay for their assistance during field works. Mr. Kahsu Kiros, driver, deserves great appreciation as he helped me to access all my field sites. xiii I am very grateful to Hanibal Lema, Hanne Hendrickx, Sofie Annys, Hailemariam Meaza, Zbelo Tesfamariam, Wouter Lonnoeye, Min Luo, Dr. Henok Kassa, Habtamu Assaye, Woldegebrial Zeweld for their support and encouragement that gave me courage. Moreover, I cannot forget to thank my friends Mr. Samuel Tesfaye and Dr. Gebeyehu Taye for their wonderful contributions to my research works. Thank you Abebe Damtew and Tesfay Berhu for your assistances. I am thankful to Dr. Sil Lanckriet, Dr. Tesfalem Ghebreyonnes and Dr. Biadgilgn Demissie for their assistance in Belgium especially during my first year in Belgium. Beside academic matters, I could not forget the best times I had with you during our social activities in Belgium as well as in Ethiopia. I would also like to express my deepest appreciation to the Special Research Fund (BOF) of Ghent University for funding this research and RIP –MU (VLIR) project for important logistic support. I am obliged to Mekelle University (MU) for giving me chance to carry out this research. Thank you Dr. Amanuel Zenebe for your supervision and supports. I am very grateful to Dr. Motuma Tolera, Wondo Genet College of Forestry, for allowing me to use his wood science laboratory. I thank Helga, Karine, Sofie for facilitating administrative issues and Wim and Steve for their services related to ICT. Thanks to Sabine Cnudde for proofreading of this manuscript. Last but not least, my especial thank goes to my family. I am very grateful to my brother Teferi Guyassa, Askalech Eba, Asmamaw Kebede, Abeba Asmamaw and all other family members for their sympathetic support and good wishes for my study. My long distance run was completed with success with the full support of my beloved wife, Helen Asmamaw. Your encouragement during all times should be much appreciated. An excellent care for my sons Kirubel and Yafet during my absence gave me a comfort to fully concentrate on my study. Many thanks to Fana for your help to take care of my children when my wife came to Belgium to visit me. Table of contents Acknowledgements ........................................................................................................... xiii Table of contents ............................................................................................................... xv List of Tables .................................................................................................................. xix List of Figures .................................................................................................................. xxi List of acronyms ............................................................................................................ xxvii Publications ................................................................................................................ xxix Summary ..................................................................................................................... 1 1 General Introduction ................................................................................. 3 1.1 Problem statement ................................................................................................... 3 1.2 Definitions ............................................................................................................... 7 1.3 Objectives and research questions .......................................................................... 8 1.4 Thesis outline ........................................................................................................ 10 1.5 Study area selection............................................................................................... 10 1.6 References ............................................................................................................. 12 Part 1 Land use, cover and management dynamics ........................................................ 17 2 Changes in land use/cover mapped over 80 Years ............................... 19 2.1 Introduction ........................................................................................................... 23 2.2 Materials and methods .......................................................................................... 25 2.2.1 Study area .................................................................................................. 25 2.2.2 Land use/cover analysis by the point counting method ............................. 27 2.2.3 Explanatory factors for LUC changes ....................................................... 32 2.2.4 Accuracy assessment of the point counting method and spatial map ........ 34 2.2.5 Data analyses ............................................................................................. 35 2.3 Results ................................................................................................................... 36 2.3.1 Geomorphic settings .................................................................................. 36 2.3.2 Change of land use/cover fraction from the 1930s - 2014......................... 37 2.3.3 Spatial distribution of land use/cover ........................................................ 39 2.3.4 Explanatory factors affecting the land use/cover ....................................... 41 2.4 Discussion ............................................................................................................. 46 2.4.1 Point counting method, APs and GE images ............................................. 46 2.4.2 Land use/cover fraction ............................................................................. 47 xv 2.4.3 Spatial change of LUC ............................................................................... 49 2.4.4 Explanatory factors of land use/cover distribution and change ................. 50 2.5 Conclusions ........................................................................................................... 51 2.6 Rreferences ............................................................................................................ 53 3 Changes in gully and soil and water conservation structure densities over the last 80 years ................................................................ 61 3.1 Introduction ..........................................................................................................
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