GROUNDWATER POTENTIALS OF BASEMENT COMPLEX AREAS: CASE OF MOPA/AMURO AND EGBE AREAS, KOGI STATE, NIGERIA BY OMONONA, OLUFEMI VICTOR (PG/M.Sc/07/42520) DEPARTMENT OF GEOLOGY FACULTY OF PHYSICAL SCIENCES UNIVERSITY OF NIGERIA, NSUKKA NIGERIA JULY, 2010. GROUNDWATER POTENTIALS OF BASEMENT COMPLEX AREAS: CASE OF MOPA/AMURO AND EGBE AREAS, KOGI STATE, NIGERIA BY OMONONA, OLUFEMI VICTOR (PG/MSc/07/42520) A RESEARCH PROJECT SUBMITTED TO THE DEPARTMENT OF GEOLOGY, FACULTY OF PHYSICAL SCIENCES UNIVERSITY OF NIGERIA, NSUKKA IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF A MASTER OF SCIENCE IN HYDROGEOLOGY JULY, 2010. i CERTIFICATION Omonona, Olufemi Victor, a post graduate student in the Department of Geology with the registration number, PG/MS.c/07/42520 has satisfactorily completed the requirements for the course and research work for the degree of Master of Science in Hydrogeology. The work embodied in this project report is original and has not been submitted in part or full for any other degree or diploma of this or any other university. _______________________________ _________________ Prof C.O. Okogbue Date Project Supervisor ________________________________ _________________ Dr. A.W. Mode Date Ag. Head of Department _________________________________ ________________ External Examiner Date ii DECLARATION Omonona, Olufemi Victor, a post graduate student in the Department of Geology with the registration number, PG/MS.c/07/42520 has satisfactorily completed the requirements for the course and research work for the degree of Master of Science in Hydrogeology. The work embodied in this project report is original and has not been submitted in part or full for any other degree or diploma of this or any other university. ________________________________ ___________________ Date Supervisor _________________________________ __________________ Head of Department Date iii DEDICATION This piece of work is dedicated to the LORD GOD ALMIGHTY, who is my Life and Light. And also to the loving memory of my sister-in-Christ and friend, Oluwatosin Mosunmola Otitoju, whose lifestyle was challenging. iv ACKNOWLEDGEMENT I would like to thank my supervisor, Prof C.O. Okogbue, for accepting to take over the supervision of the work as soon as my former supervisor, Prof H.I. Ezeigbo proceeded to the life beyond in November, 2008. I am indeed very grateful for taking some time out of his very busy schedule to peruse the thesis. His criticisms, corrections and suggestions are clearly manifested in the quality of the work. The efforts of my late supervisor are worthy of mentioning. He spurred my interest in hydro-geophysics and encouraged me to pursue the topic despite my lack of what it entails in the first instance. To all members of staff of the Department of Geology, University of Nigeria, Nsukka, I appreciate you for providing a good working environment. Without this, it would have been difficult to complete this work. Many thanks to Mr. S. O Onwuka, whom I had sessions of beneficial discussions and he gave his time for a critical review of the manuscript. I am particularly grateful to Mr. Olawole J.F. and Mr. Kunle Rasaq of Lower River Niger Basin and Rural Water Development Authority, Ilorin, Kwara State for providing the primary vertical electrical sounding and borehole data for this work. I must not also forget to appreciate the moral and spiritual supports I received from members of the Graduate Student Fellowship and Christ Church Chapel, Sunday School Department, University of Nigeria, Nsukka. And also, to a host of friends too numerous to mention I say “Thank You All”. And to my parents; Revd E.A. and Mrs. J.A. Omonona, who were my first teachers. I am grateful for your lives; you believed in and encourage the education of your children. Finally, to my Lord and Saviour Jesus Christ, He is my life and light. He is the Living Water who bids each one of us to come and drink. Thank You Jesus! v ABSTRACT Investigations have been carried out for groundwater potentials, aquifer protective capacity and hydro-geochemical characteristics in Mopa/Amuro-Egbe Areas of Kogi State, Nigeria. The areas are underlain by the Nigeria Basement Complex consisting of PreCambrian rocks, made up of porphyroblatic granites, porphyritic granite, quartz granite, pegmatite, augen gneiss and migmatite gneiss. Static water level of 103 water wells were measured at the peak of dry season, and the results used to generate hydraulic head data and hydraulic head map. A total of 81 vertical electrical soundings data were interpreted using curve-matching and computer aided techniques. Groundwater potential zones were delineated based on geology, hydro-geological and geo-electrical data. A total of 20 samples, three from boreholes and 17 from hand dug wells, were analyzed for their physiochemical properties with the intent of assessing their quality and characteristics. The static water level range between 0.01m and 10.16m. The hydraulic head map revealed two groundwater flow directions: northeastern and eastern. One main converging (collecting) zone and three diverging (radiating) zones were deciphered. The former coincides with areas of good groundwater potential zones and the latter low groundwater potential. The studies reveal three groundwater potential zones namely, high, medium and low. The result of the interpretation of the geophysical data shows that the area is characterized by variable subsurface layering ranging from two layers to five layers. Three distinct aquifer protective zones were identified namely moderate, poor and weak. The factors/processes which control the sources of elements in the groundwater include geologic/lithologic factor, contamination via weathering, agricultural drainage and bacteriological factors. Four hydro-geochemical facies (water types) were deduced from the − −2 −2 − Piper diagram. These include Na-K- HCO 3 , Ca-(Mg) - SO 4 , Ca-Mg-( SO 4 )- HCO 3 and −2 Na-K-( SO 4 ). The water quality was found to be good for all agricultural purposes. Water treatment may be required for some of the groundwater sources for drinking purposes because their elemental concentrations are above WHO (1993) guideline values. vi TABLE OF CONTENTS PAGES TITLE PAGE ii CERTIFICATION iii DECLARATION iv DEDICATION v ACKNOWLEDGEMENT vi ABSTRACT vii TABLE OF CONTENT viii LIST OF TABLES ix LIST OF FIGURES x LIST OF APPENDICES xi CHAPTER ONE: INTRODUCTION 1.1 Background Information 1 1.2 Location and Accessibility 1 1.3 Climate and Vegetation 2 1.4 Relief and Drainage 2 1.5 Aims and Objectives 2 1.6 Review of Previous Works 5 CHAPTER TWO: GEOLOGY AND HYDROGEOLOGY 2.1 Regional Geological Setting 9 2.2 Regional Hydrogeological Setting 14 2.3 Local Geology 15 2.4 Local Hydrogeology 15 CHAPTER THREE: METHODS OF STUDY 3.1 Geological Investigation 16 3.2 Geophysical Method 16 3.3 Hydro-geophysical Investigation 16 3.4 Data Analysis 20 vii CHAPTER FOUR: RESULTS AND DUSCUSSION 4.1 Local Geology and Groundwater Yield 23 4.2 Static Water Level and Hydraulic Head: Groundwater Flow Directions 23 4.3 Geo-electrical Characterization 28 4.4 Depth to Bedrock (Overburden Thickness) 31 4.5 Basement Relief 31 4.6 Evaluation of Aquifer Protective Capacity 38 4. 7 Groundwater Potentials Evaluation 42 4.8 Groundwater Quality and Hydro-geochemistry 44 4.9 Sources of Elements and the Controlling Processes 65 4.10 Hydro-Geochemical Facies 69 4.11 Stiff Pattern 73 CHAPTER FIVE: CONCLUSION 5.1 Conclusion and Recommendation 75 REFERENCES 78 APPENDICES 85 viii LIST OF TABLES Table1. Result of Borehole Yield and Static Water Level 24 Table 2 Static Water Level and Hydraulic Head 25 Table 3 Layer Resistivity, Thickness and Curve Types 29 Table 4 Longitudinal Conductance /Protective Capacity Rating 39 Table 5 Longitudinal Conductance and Aquifer Protective Capacity 40 Table 6 Aquifer potential as a Function of Weathered Layer Thickness and Resistivity 45 Table 7 Aquifer Potential as a Function of Depth to Bedrock and Bedrock Resistivity 46 Table 8 Physical and Biological Parameters 48 Table 9 Chemical Parameters 49 Table 10 Cations and Anions 50 Table11 Heavy Metals 52 Table 12 Hardness Classification of Water 55 Table13 Modified Richard Quality Classification of Irrigation Water 64 Table14 Suggested Limit for Magnesium Drinking Water for Livestock 64 Table 15 Guidelines for Levels of Toxic Substances in Live stocks Drinking Water 64 Table 16 Principal Component Analysis 66 Table 17 Correlation Matrix 67 ix LIST OF FIGURES 1 Location Map of the Study Area 3 2 Drainage Map of the Study Area 4 3 Geological Map of the Study Area 17 4 Sketch Diagram of Schlumberger Array 18 5 Base Map of the Study Area Showing the VES Locations 19 6 Base Map of the Study Area Showing the Pumping Test Locations 21 7 Base Map of the Study Area Showing Water Sampling locations 22 8 Static Water Level Map of the Study Area 26 9 Hydraulic Head Map of the Study Area 27 10 Frequency Distribution of observed Curve Types 30 11 Top Soil Thickness Map of the Study Area 32 12 Top Soil Resistivity Map of the Study Area 33 13 Weathered Layer Isopach Map of the Study Area 34 14 Weathered Layer Isorestivity Map of the Study Area 35 15 Overburden Map of the Study Area 36 16 Basement Relief Map of the Study Area 37 17 Aquifer Protective Capacity Rating 41 18 Aquifer Protective Capacity Map of the Study Area 43 19 Groundwater Potentials Map of the Study Area 47 20 Spatial Distribution of Arsenic in the Study Area 57 21 Spatial Distribution of Cadmium in the Study Area 59 22 Spatial Distribution of Chromium in the Study Area