SAKARYA UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY THE USE OF INTEGRATED GEOPHYSICAL METHODS FOR GROUNDWATER EXPLORATION IN GHANA M.Sc. THESIS Hafiz MOHAMMED NAZIFI Department : GEOPHYSICAL ENGINEERING Supervisor : Prof. Dr. Levent GÜLEN June 2015 ii ACKNOWLEDGEMENTS My first and foremost gratitude goes to the Almighty Allah for His unending blessing, graces and mercies throughout my life. I sincerely thank the Republic of Turkey Prime Ministry Presidency Turk Abroad and related Community for providing me with scholarship and opportunity to study in Turkey. I am very grateful to my family and friends for their support, encouragement and special prayers. I extend endless thanks to my advisor and supervisor Prof., Dr. Levent Gülen (Sakarya University) for his motivation, encouragement, supports, recommendations and his fatherly love for me. I am also thankful to Assist. Prof., Dr. Can Karavul (Sakarya University) for his assistance, recommendation and the constructive criticism throughout this thesis work. I am grateful to Mr. David Dotse Wemegah of KNUST – Kumasi for his assistance in drawing the map of the district and also I am grateful to him and Dr. Kwesi Preko of KNUST – Kumasi, for the effort they put in for me to get the data for this work and for their numerous assistance, advices and motivation. I am highly indebted to Mr. Evans Manu of CSIR for granting the dataset for this work and for the permission to use the dataset.I also thank the faculty members and the students of the Geophysical Engineering Department of Sakarya University for their immense supports. Finally, I am grateful to the staffs and all the students (especially my roommates) of the Serdivan Erkek Öğrenci Yurdu; with whom I spent three memorable academic years together. iii TABLE OF CONTENTS DECLARATION ..................................................... Error! Bookmark not defined. ACKNOWLEDGEMENTS .................................................................................... iii TABLE OF CONTENTS ........................................................................................ iv LIST OF SYMBOLS AND ABBREVIATIONS ..................................................... x LIST OF FIGURES ............................................................................................... xiii LIST OF TABLES ................................................................................................... xx SUMMARY .......................................................................................................... xxii ÖZET……………………….………………………………………………….. xxiii CHAPTER 1. INTRODUCTION .................................................................................................... 1 1.1. General Introduction ............................................................................... 1 1.2. Statement of Problem .............................................................................. 3 1.3. Justification of the Study ......................................................................... 4 1.4. Significance of the Study ........................................................................ 4 1.5. Purposes and Objectives of the Study ..................................................... 5 1.6. Scope of Work ......................................................................................... 5 CHAPTER 2. LITERATURE REVIEW AND STUDY AREA ...................................................... 6 2.1. Groundwater ........................................................................................... 6 2.1.1. The sources and origin of groundwater .......................................... 6 2.1.2. Groundwater occurrence and distribution ...................................... 8 2.1.3. Water table and aquifer ................................................................. 10 2.1.3.1. Water table ............................................................................. 10 iv 2.1.3.2. Aquifer ................................................................................... 11 2.1.4. Hydraulic properties of rocks ........................................................ 13 2.1.4.1. Porosity .................................................................................. 14 2.1.4.2. Specific yield (Sy) and Specific retention (Sr) ....................... 15 2.1.4.3. Recharge and discharge ......................................................... 16 2.1.4.4. Coefficient of permeability.................................................... 17 2.1.4.5. Transmissivity (T) ................................................................. 17 2.1.4.6. Storativity .............................................................................. 18 2.1.5. Groundwater quality ..................................................................... 18 2.2. Literature Review ................................................................................... 21 2.2.1. Geophysical methods used in groundwater prospecting ............... 21 2.2.1.1. Magnetic method ................................................................... 23 2.2.1.2. Electric and electromagnetic methods ................................... 24 2.2.1.3. Ground penetrating radar ....................................................... 25 2.2.2. Some previous groundwater exploration projects in Ghana ......... 26 2.2.2.1. Main methods use in groundwater investigation in Ghana ...... 26 2.2.2.2. Some groundwater geophysical investigation projects ......... 26 2.2.3. Study area ...................................................................................... 29 2.2.3.1. Brief introduction .................................................................. 29 2.2.3.2. Location, topography and drainage pattern ........................... 31 2.2.3.3. Climate and vegetation of the study area .............................. 32 2.2.3.4. Regional geological and hydro-geological settings ............... 33 2.2.3.5. Local geology and hydrology of the study area .................... 35 2.2.3.6. Socio – economic activities of the study area ....................... 36 CHAPTER 3. THEORETICAL BACKGROUND ........................................................................ 38 3.1. Resistivity Method ................................................................................. 38 3.1.1. Introduction ................................................................................... 38 3.1.2. Brief historical background of eesistivity method ........................ 39 3.1.3. Electrical resistivity in earth materials .......................................... 39 3.1.4. Theory of electrical resistivity method ......................................... 41 3.1.4.1. Basic theory ........................................................................... 41 v 3.1.4.2. Current flow in ground .......................................................... 43 3.1.4.3. Depth of penetration in resistivity method ............................ 47 3.1.5. Electrode arrays (spread)............................................................... 48 3.1.5.1. Wenner array ......................................................................... 48 3.1.5.2. Schlumberger array ............................................................... 49 3.1.5.3. Dipole - dipole array .............................................................. 50 3.1.5.4. Pole –dipole array .................................................................. 50 3.1.5.5. Pole – pole array .................................................................... 51 3.1.6. Limitations of the resistivity method ............................................ 52 3.1.7. The use of resistivity method in groundwater explorations .......... 52 3.2. Electromagnetic Method ........................................................................ 53 3.2.1. Introduction ................................................................................... 53 3.2.2. Brief historical background of EM method .................................. 53 3.2.3. Electrical conductivity in earth materials ...................................... 54 3.2.4. Theory of the electromagnetic method ......................................... 54 3.2.4.1. Basic theory of electromagnetic method ............................... 54 3.2.4.2. Fundamental quantities and field equation ............................ 56 3.2.4.3. Attenuation of EM fields, and depth of penetration .............. 58 3.2.4.4. Slingram and ground conductivity meters (GCM) ................ 60 3.2.5. Limitation of EM methods ............................................................ 63 3.2.6. The Slingram and GCM in groundwater prospecting ................... 63 CHAPTER 4. INSTRUMENTATION AND METHODOLOGY .................................................. 65 4.1. Instrumentation ...................................................................................... 65 4.1.1. Instrumentation of the Resistivity method .................................... 65 4.1.1.1. Description of ABEM Terrameter SAS 1000C ..................... 66 4.1.1.2. Principle of operation of ABEM Terrameter SAS 1000C ....... 66 4.1.1.3. ABEM Terrameter SAS 1000C handling and operation ....... 67 4.1.2. Instrumentation of the electromagnetic method ............................ 68 4.1.2.1. Description of the Geonics EM 34-3 ..................................... 68 4.1.2.2. Principle of operation of Geonics EM34-3 ........................... 69 4.1.2.3. Handling and operation of Geonics EM34-3 ........................ 70 vi 4.2. Methodology