Key Features:
No, of pages: 78
Abstract:
An investigation was carried out on the groundwater potentials and aquifer protective capacity of the Ishiagu area, in 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 were thoroughly characterized using 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. The 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 potential also have good aquifer protective capacity. Groundwater development should therefore be concentrated more in areas of good groundwater potential for a continuous/steady supply of potable water.
Table of Content:
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
LIST OF TABLES
Table1. Elevation and depth data from hand dug wells 22
Table 2VES and WELLS location with coordinates 24
Table 3 Thickness, depth and Resistivity of layers in sounding points 25
Table 4 Frequency distribution of curve types 26
Table 5 Frequency and percentage distribution of different layer models 31
Table 6 Summary of aquifer parameters 35
Table 7 Classification of aquifer based on transmissivity 36
Table 8 Modified model longitudinal conductance/protective capacity rating 39
Table 9 Aquifer protective capacity rating across sounding locations 40
Table 10 Summary of aquifer protective capacity 41
LIST OF FIGURES
1 Map of Ishiagu area showing accessibility and drainage 3
2 Regional stratigraphic map of Study Area 10
3 Map showing local geology of the Ishiagu area 11
4 Sampling station map 14
5 Illustration of the of Schlumberger Array 15
6 Taking reading in one of the field locations 16
7 Groundwater flow direction map 23
8 Typical HA Curve from one of the study locations 28
9 Typical HKHK Curve from one of the study locations 29
10 Typical HKQH Curve from one of the study locations 30
11 Geoelectric sections of VES 9, VES 4, VES 17, VES 3 32
12 Geoelectric sections of VES 9, VES 6, VES 10, VES 12 33
13 Groundwater Potentials Map of the Study Area 37
14 Aquifer Protective Capacity Map of the Study Area 43
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