Characterization of Aquifers and Hydrochemistry in Volcanic Terrain of Central Ethiopia Tarmaber basalt Spring A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Masters of Science in Hydrogeology Advisor: Tenalem Ayenew (prof.) By: Mekdes Nigatie Enideg June 2012 ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES DEPARTMENT OF EARTH SCIENCES Characterization of Aquifers and Hydrochemistry in the Volcanic Terrain Central Ethiopia By: Mekdes Nigatie Endge A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Hydrogeology Approved by the board of examiners Tigistu Haile (Ph.D) ___________________________________________ Head of the Department and Chair man Tenalem Ayenew (prof.) ________________________________________ Advisor Seifu Kebede (Ph.D) ____________________________________________ Internal examiner GezhegnYirgu (prof.) ____________________________________________ Internal examiner June, 2012 Table of Contents List of Figures .............................................................................................................................................. iv List of Tables ................................................................................................................................................ v List of Plates ................................................................................................................................................. v Acknowledgments ........................................................................................................................................ vi Acronyms .................................................................................................................................................... vii Abstract ...................................................................................................................................................... viii CHAPTER 1 .................................................................................................................................................... 1 INTRODUCTION ............................................................................................................................................. 1 1.1. Background ........................................................................................................................................ 1 1.2. Objectives of the Study ...................................................................................................................... 3 1.3. Significance of the Study ................................................................................................................... 3 1.4. Research Methodology ...................................................................................................................... 3 1.5. Literature Review ............................................................................................................................... 4 CHAPTER 2 .................................................................................................................................................... 6 DESCCRIPTION OF THE STUDY AREA ............................................................................................................. 6 2.1. Location .............................................................................................................................................. 6 2.2 Geomorphology .................................................................................................................................. 7 2.2.1. Blue Nile-Jema-Muger-Guder River Gorges and low elevation area ......................................... 7 2.2.2. The Central Plateau ..................................................................................................................... 7 2.2.3. Entoto-Chelelka-Guragudda-Wechecha-Chilmo Mountains ...................................................... 8 2.3. Climates and Hydrology ................................................................................................................... 10 2.3.1. Climate ...................................................................................................................................... 10 2.3.2. Hydrology ................................................................................................................................. 11 CHAPTER 3 .............................................................................................................................................. 14 GEOLOGY ................................................................................................................................................. 14 3.1 Regional Geology ............................................................................................................................. 14 3.2. Local Geology .................................................................................................................................. 15 3.2.1. Mesozoic Sedimentary Rocks ................................................................................................... 16 3.2.2. Tertiary volcanic Rocks ............................................................................................................ 18 3.2.3. Quaternary volcanic rock and sediments .................................................................................. 22 3.2.3.1. Quaternary Volcanic rocks ..................................................................................................... 22 3. 2.3.2. Quaternary Lacustrine and Alluvial Deposits ....................................................................... 23 CHAPTER 4 .................................................................................................................................................. 26 HYDROGEOLOGY ......................................................................................................................................... 26 4.1 Hydro Geological Classification /Characterization ............................................................................ 26 4.1.1 Qualitative Parameters ............................................................................................................... 27 4.1.2. Quantitative Parameters ............................................................................................................ 27 4.2. Aquifer classification of the area ..................................................................................................... 28 4.2.1. Extensive and highly productive porous aquifer ....................................................................... 28 4.2.2. Extensive and Highly Productive Fissured and Karast Aquifer ................................................ 28 4.2.3. Extensive and Highly Productive Fissured Aquifer .................................................................. 29 4.2.4. Extensive and Moderately Productive Porous Aquifer ............................................................. 31 4.2.5. Extensive and Moderately Productive Fissured Aquifer........................................................... 32 4.2.6. Low Productive Aquifer ............................................................................................................ 33 4.2.7. Aquiqulid .................................................................................................................................. 34 4.3. Determination of Aquifer Parameters from Pumping Test Data ...................................................... 35 4.4. Ground Water Potential (Aquifer potential) .................................................................................... 37 4.5. Hydrogeological Structures .............................................................................................................. 38 4.6. Aspects of groundwater recharge and discharge .............................................................................. 40 4.6.1. Ground Water Recharge ............................................................................................................ 40 4.6.2. Ground Water Discharge .......................................................................................................... 41 4.7. Ground Water Flow System ............................................................................................................. 45 CHAPTER 5 .............................................................................................................................................. 48 HYDROCHEMISTRY ...................................................................................................................................... 48 5.1. General ............................................................................................................................................. 48 5.2. Groundwater Sampling .................................................................................................................... 48 5.3. Physical Parameters ......................................................................................................................... 50 5.3.1. Hydrogen-Ion Activity (PH) ..................................................................................................... 50 5.3.2. Electrical conductance (EC) .....................................................................................................