ABSTRACT
In a bid to determine the groundwater potential of some parts Orsu and environs, which lies within latitude N5º53.858΄ to N5º47.572΄ and longitude E7º0.847΄ to E6º56.988΄, a total of ten (10) vertical electrical soundings were carried out. The study area belongs to the Anambra basin which is one of Nigeria’s most important hydrological basins. It is overlain by the Miocene to recent Benin formation and Eocene Ameki formation.Equipment such as ABEM terrameter SAS 4000, 12volts battery, global positioning system (GPS), four electrodes, reel of cables, clip, hammer etc were used during the data acquisition process and were processed using FORTRAN 2D Resistivity inversionSoftware. Moreso, Surfer 14 program was used to provide the transmissivity, hydraulicconductivity, diffusivity, and storativity maps, as the imaging pictures of the subsurfacein the form of contour maps. Results from the processed data revealed that the study areaconsist of top soil, sand, clayey sand and clay. Out of a total of 10 Vertical electricalsoundings obtained from selected locations in the study area, All VES points indicated a5-layer curve except VES 3 and VES 5 which have shown a 7-layer lithology. VES 2 and6 has shown KH curve type (i.e. ρ1 ρ3> ρ4< ρ5 characteristic), VES 4, VES 7 andVES 8 has also shown HA (i.e. ρ1> ρ2< ρ3< ρ4< ρ5 characteristic). VES 1, VES 9 and VES10 have shown KA, AK & HK curves respectively. However, from analyses made,greater part of the region is prolific (that is, high groundwater potential). The depth towater from VES 1 to VES 10 were estimated as 92.8m, 87.0m, 91.0m, 104.0m, 139.0m,139.93m, 214.0m, 137.0m, 67.0m, 37.0m respectively. Shallow aquifer systems wereencountered at areas such as: Akwakuma Okporo, Okwuruokwuo Amannachi, UmualumIsiafor Ofeahia, Umuoka Asaa, and Amaruru , while deep aquifer systems were seen atareas such as: Afor-Iduu Amaebu Ebenator, St. peters, Umuezeala Amaebu, Umuhu-Okabia, Umucheke Omuokabia Awo-Idemili, Uda Orsu-Ihiteukwa. Areas such asAmannachi, Ebenator, Amaebu and Isiafor ofeahia are highly prolific and have shownhigh level of transmissivity of about 3000 to 4000m2/day and high storativity rangingfrom 0.0004 to 0.00058. These areas have also shown high rate of diffusivity with valueranging from 5500000 to 8500000, except Amaebu which have shown very low level ofdiffusivity.Keywords: Groundwater, Vertical Electrical Sounding, Transmissivity, HydraulicConductivity, Diffusivity, and Storativity
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Abstract vi
Table of Contents vii
List of Figures x
List of Plates xi
List of Tables xii
CHAPTER ONE: INTRODUCTION
1.1 Background Information 1
1.2 Aim and Objectives 2
1.2.1 Aim 2
1.2.2 Objectives 2
1.3 Location and Accessibility 2
1.4 Justification of Study 5
1.5 Climate and Vegetation 5
1.6 Geological settings of the study area 6
1.6.1 Regional Geology 6
1.6.2 Local Geology of the study area 6
1.6.2.1 Benin formation 6
1.6.2.2 Ameki formation 7
1.7 Groundwater 9
1.8 Porosity and Permeability 10
1.8.1 Porosity 10
1.8.2 Permeability 11
1.9 Aquifer and Aquiclude 12
1.10 Scope and Limitations of the study 13
1.11 Relief 14
CHAPTER TWO: LITERATURE REVIEW
2.1 Previous works 15
2.2 Review of Geoelectric techniques 16
CHAPTER THREE: MATERIALS AND METHOD
3.1 Desk study 18
3.2 Reconnaissance survey 18
3.3 Detailed study 18
3.4 Field equipments 19
3.4.1 Global positioning system (GPS) 19
3.4.2 ABEM Terrameter (SAS 4000) 19
3.4.3 Electrodes 20
3.4.4 Cables 20
3.4.5 Clips 20
3.4.6 Hammer 21
3.4.7 Rollers 21
3.4.8 Protective wears 21
3.4.9 Matchet 21
3.4.10 Compass 21
3.5 Field Procedures 21
3.6 Data Presentation 23
3.7 Principles of Electrical Resistivity Method 24
3.8 Theory of Electrical Resistivity in rocks 25
3.9 Apparent resistivity 27
3.10 Observed Precautions 30
CHAPTER FOUR: RESULT PRESENTATION AND INTERPRETATION
4.1 Data processing 32
4.2 Qualitative interpretation 36
4.2.1 Description of the various curve types 36
4.3 Quantitative interpretation 36
4.4 Profiles 37
4.4.1 Profile One (A-B) 37
4.4.2 Profile Two (C-D) 39
4.4.3 Profile Three (E-F) 41
4.5 Groundwater Potential evaluation 43
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION
5.1 Conclusion 48
5.2 Recommendation 50
References 51
Appendix I 56
Appendix II 66
LIST OF FIGURES
Figure 1.1 Location map of the study area showing VES locations 4
Figure 1.2 Geologic map of the study area 8
Figure 3.1 General four electrodes configuration for resistivity
measurement, consisting of a pair of current electrodes (A, B)
and a pair of potential electrodes (M, N) (Adapted from
Lowrie, 1997). 28
Figure 4.1 Correlated Geoelectric section along profile A-B 38
Figure 4.2 Correlated Geoelectric section along profile C-D 40
Figure 4.3 Correlated Geoelectric section along profile E-F 42
Figure 4.4 Aquifer thickness of the VES points in the study area 43
Figure 4.5 3D Contour map of the study area showing
transmissivity variations 44
Figure 4.6 3D Contour map of the study area showing
Hydraulic conductivity variations 45
Figure 4.7 3D Contour map of the study area showing
Diffusivity variations 46
Figure 4.8 3D Contour map of the study area showing
storativity variations 47
LIST OF PLATES
Plate 3.1 ABEM Terrameter SAS 4000 20
Plate 3.2 Researcher and some crew members during data
collection at one of the VES points. 22
Plate 3.2 Data acquisition process at VES 2
(Okwurukwuo Amannachi, Orsu) 23
LIST OF TABLES
Table 1.1 Geologic Formation Outcropping at the study area 9
Table 1.2 Porosity and permeability of some geologic materials
(after Montgomery, 1990). 12
Table 4.1 Vertical Electrical Sounding (VES) Summary 33
Table 4.2 Hydrogeophysical parameters of the study area 34
Table 4.3 Layer resistivities at different 35
Table 4.4 Aquifer hydraulic parameters 35
Table 4.5 Qualitative interpretation of the data obtained from the
study area 36
Obodo, W., u., O & sabinus, I (2019). Geo Electrical Assessment of Groundwater Potentials of Some Parts of Orsu and Environs, South Eastern Nigeria. Afribary. Retrieved from https://track.afribary.com/works/geoelectrical-assessment-of-groundwater-potentials-of-some-parts-of-orsu-and-environs-southeastern-nigeria
Obodo, Wisdom, et. al. "Geo Electrical Assessment of Groundwater Potentials of Some Parts of Orsu and Environs, South Eastern Nigeria" Afribary. Afribary, 07 Sep. 2019, https://track.afribary.com/works/geoelectrical-assessment-of-groundwater-potentials-of-some-parts-of-orsu-and-environs-southeastern-nigeria. Accessed 06 Nov. 2024.
Obodo, Wisdom, Obodo U. and Ibeneme Sabinus . "Geo Electrical Assessment of Groundwater Potentials of Some Parts of Orsu and Environs, South Eastern Nigeria". Afribary, Afribary, 07 Sep. 2019. Web. 06 Nov. 2024. < https://track.afribary.com/works/geoelectrical-assessment-of-groundwater-potentials-of-some-parts-of-orsu-and-environs-southeastern-nigeria >.
Obodo, Wisdom, Obodo U. and Ibeneme Sabinus . "Geo Electrical Assessment of Groundwater Potentials of Some Parts of Orsu and Environs, South Eastern Nigeria" Afribary (2019). Accessed November 06, 2024. https://track.afribary.com/works/geoelectrical-assessment-of-groundwater-potentials-of-some-parts-of-orsu-and-environs-southeastern-nigeria