DETERMINATION OF AQUIFER PARAMETERS IN THE ISHIAGU EBONYI STATE USING GEOELECTRIC METHOD

ABSTRACT

An investigation was carried out on the groundwater potentials and aquifer protective capacity of Ishiagu area, southeastern Nigeria. The study area lies within the lower Benue trough of Nigeria and is underlain by the Albian Asu River Group and the Turonian Ezeaku Shales.The methodologies employed in the study include measurements of static water levels of 15 hand dug wells, pumping tests carried out on 4 boreholes and vertical electrical sounding (VES) of 20 stations. Groundwater potentials of the area was thoroughly characterizedusing aquifer parameters of hydraulic conductivity and transmissivity within unit cells.These parameters were supplemented with those determined from empirical relationships.The hydraulic conductivity and transmissivity determined from the pumping test data range from 0.6m/day to 3.04m/day and 4.86m2/day to 34.93m2/day respectively while those from empirical relationships range from 0.04m/day to 4.34m/day and 0.07m2/day to 61.69m2/day respectively.Three groundwater potential ratings were defined based on the aquifers’ hydraulic conductivity and transmissivity data; poor (45%), fairly good (35%) and good (20%). The hydraulic head map reveals two divergence and two convergence zones. The computed hydraulic heads range from 58.2m to 84.5m.Vertical electrical sounding reveals that the area is characterized by 4-, 5- and 6- subsurface geo-electric layers with the 6-layer type being the dominant type. Longitudinal unit conductance of the 20 VES stations was estimated from the layers’ resistivity and thickness data.Longitudinal unit conductance of the overburden units ranged from 0.07mhos to 2.22mhos. Based on the estimated longitudinal unit conductance, three aquifer protective capacity types were defined namely, weak (25%), moderate (40%) and good (35%). It was observed that areas of good groundwater potentials also have good aquifer protective capacity. Groundwater development should therefore be concentrated more in areas of good groundwater potential for continuous/steady supply of potable water.  

TABLE OF CONTENTS

TABLE OF CONTENT                                                                                      PAGES

TITLE PAGES                                                                                                             ii

CERTIFICATIONiii

DEDICATIONiv

ACKNOWLEDGEMENTv

ABSTRACT                                                                                  vi

TABLE OF CONTENT                                                                                               vii

LIST OF TABLES ix

LIST OF FIGURESx

LIST OF APPENDICESxi

CHAPTER ONE: INTRODUCTION

1.1 Background Information 1

1.2 Objectives of the study                                                                                             2

1.3 Location and Accessibility                                                                                       2

1.4Drainage, Climate and Vegetation                                4

1.5Literature review                                                                                                      4

CHAPTER TWO: GENERAL GEOLOGY AND HYDROGEOLOGY

2.1 Regional Geology 7

2.2 Hydrogeology9

CHAPTER THREE: MATERIALS AND METHODS 

3.1 Study materials                                                                         12

3.2 Field study method                              12

3.3 Field data presentation and interpretation                                                              17

3.4 Data Analysis                                                                                                         17

CHAPTER FOUR: RESULTS AND DUSCUSSION

4.1 Groundwater flow direction                                                                                   21

4.2 Qualitative results of VES                                                             21

4.3 Quantitative results of VES                                                         27

4.4 Groundwater Potential                                                                                            34

4.5 Aquifer protective capacity                                                                                    34

CHAPTER FIVE: CONCLUSIONS

REFERENCES                               45

APPENDICES                              50