Omonona and Okogbue I.Pdf

GROUNDWATER POTENTIALS OF BASEMENT COMPLEX AREAS: CASE OF MOPA/AMURO AND EGBE AREAS, KOGI STATE, NIGERIA

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

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.

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

______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 60 23 Spatial Distribution of Lead in the Study Area 61 24 Spatial Distribution of Manganese in the Study Area 63 25 Piper Tri-linear Diagram 70 26 Hydrochemical Facies Map 72 27 Stiff Pattern Diagram (A-T) 74

x APPENDICES Appendix 1 Static Water Level and Hydraulic Head 85 Appendix 2 summary of vertical electrical sounding 89 Appendix 3 Topsoil, Weathered and Fractured Layers’ Thicknesses and Resistivities 92 Appendix 4 Basement Relief 99 Appendix 5 Longitudinal Conductance and Aquifer Protective Capacity 104 Appendix 6 Groundwater Potential Rating 109 Appendix 7 2-D Geo-electric Sections and Aquifer Types 121

xi CHAPTER ONE

INTRODUCTION

1.1 Background Information

Evaluation of groundwater quantity and quality is essential for development of civilization and to establish database for planning future water resources development strategies (Omar et al., 2006). The study area, Mopa-Amuro and Egbe belong to Mopa/Amuro and Yagba-West Local Government Areas respectively in Kogi State. The area is underlain by the Precambrian Basement Complex. It is made up of three towns and several agricultural villages, and covers an approximate area of 140.4sqm. Two industries (Mopa Brewery and Boja Plastic Ltd) are located within the area. Water supply in the area is obtained from shallow hand dug wells and boreholes as well as surface water. Surface water sources include River Kampe and its tributaries one of which is River Omi, which is dammed at Omi village. The dam is named Omi Dam. Since Mopa and Egbe became the administrative headquarters of Mopa/Amuro and Yagba West Local government councils respectively in the last decade, the population of the study area has been on the increase and the demand for water for drinking and domestic purposes has escalated too. Because of the ephemeral nature of most of the surface water, the higher cost of constructing and maintaining dams, treatment and transport of surface water for supply of potable water, groundwater forms the main water supply for domestic and drinking purposes. This study is thus geared at providing part of the frame work for planning, development and management of groundwater resources of the area.

1.2 Location and Accessibility Mopa–Amuro and Egbe are within longitude 5 0 30 1 and 6 0 02 1 East and latitude 8 0 00 1 and 8 0 15 1 North (Figure 1). The accessibility of the settlements in the area is enhanced by good road networks. The three towns, Mopa, Amuro and Egbe are linked by a major road, the well-tarred Ilorin- Kabba Trunk road. Other settlements (villages) are well connected by fairly good secondary and minor roads except the road linking Odo-Ara and Igbaruku villages which is not tarred and in a bad state. The road network between Egbe and Ogbe was under construction at the time of the investigation.

1.3 Climate and Vegetation The climate of the study area is made up of two major and distinct seasons: a wet season which usually lasts from March to October and a dry season which lasts from November to February. Occasionally there are rainfalls in the first two months of the year. Annual mean rainfall is about 1375mm.The mean maximum temperature is 30.56 0 c and minimum temperature is 20.00 0 c. The hottest months are February and March while the coldest months are November, December and January, which are characterized by warm sunshine and harmattan. The vegetation of the area conforms to the Guinea Savannah type characterized by open parkland trees and bushes (Mev- Hydrosearch, 2001).

1.4 Relief and Drainage The western and southern parts of Egbe have series of long gentle ridges trending North-South, separated by flat open valleys. The range of hills between Odo-Ara and Oke-ere averaging about 427 metres above mean sea level with 595 metres above mean sea level as the peak represents the highest parts of the area. The hills are composed of granite-gneiss and amphibolites stiffened by thick low- dipping dykes of pegmatite. The Mopa-Amuro district is dominated by fairly high hill ranges that are separated by flat open valleys. The highest point above mean sea level is the Abi Hill. It is 683 metres above mean sea level and is composed of migmatite and amphibolites with dykes of pegmatite. The whole of the study area is drained by River Kampe and its tributaries of Oyi, Ebba, Erigi and Ahuru (Figure 2). 1.5 Aims and Objectives

The aims of the study included: (I) To determine the groundwater potential of the study area which is underlain by the basement complex. (II) To classify this potential into zones of high, moderate and low potentials, and

Figure 1: Location Map of the Study Area.

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(III) To determine the quality of the groundwater so as to establish its applicability for domestic, agriculture and industrial uses.

1.6 Review of Previous Work The hydrogeology of Mopa-Amuro and Egbe areas has not been studied as much as other Basement Complex terrains in the country. The literature review presented herein therefore is a general review of previous works on the groundwater potentials of Basement Complex areas. Olayinka (1971) in his survey of the groundwater potentials of the southwestern states of Nigeria observed that the thickness of the overburden is very variable and only 6.89 metres of the overburden is partially weathered granite gneiss. Water quality analysis results showed that the water from the region is acidic. Faniran and Omorinbola (1978) evaluated the groundwater reserves of the Basement Complex rocks of southwestern Nigeria. In their survey they concluded that: the zone of saturation in the weathered mantle is generally widespread, especially in low-relief humid areas of considerable weathering depth; the pattern of groundwater level fluctuation within regolith depicts the seasonal pattern of rainfall distribution; considerable replenishment of groundwater within the weathered mantle does occur, especially in areas of low relief, widespread and thick regoliths and adequate rainfall; and the factors which largely determine the quantity of water available at any given time in a well sunk in a regolith include the transmissibility of the weathered material, total well depth, nearness to valley bottom, size of drainable region and topography. Olorunfemi, et al. (1999 ) used geophysical investigations, lineament map and water level measurements to evaluate the groundwater potentials of Akure metropolis, southwestern Nigeria. The various techniques agreed in delineating zones of high, moderate and low groundwater potentials. Idowu and Ajayi (1998) conducted a comparative study of occurrence and potentials of groundwater in basement complex rocks and sedimentary rocks of Ogun State, southwestern Nigeria. They observed that two major aquifers in the basement complex rocks serve the population in the basement terrain and that the adequacy of groundwater is the same as in the sedimentary rock environment for domestic, agriculture and industrial uses. Adelusi, et al. (2001) with the combined methods of Very Low Frequency Electromagnetic (VLFE) survey and electrical resistivity sounding (ERS), evaluated the

5 groundwater potentials of the Basement Complex of Ero Area of Ondo State which results showed that, the northeast and central portion of the area has high groundwater potentials because of the thick overburden underlain by fractured bed that characterize those areas. Also the central portion was observed to be characterized with bedrock depression/fracture plane. Ariyo and Adeyemi (2008) studied the aquifer characteristics of the Basement Complex /Sedimentary Transition, South-West, Nigeria. They observed that in the Basement Complex, out of the ten Schlumberger curves from the soundings, nine show a three-layer (H-type curve) while the other one is a four-layer ( KH-type of curve). The dominant aquifers in the basement complex are the weathered /fractured layers with resistivity value range of 35 Ωm −1 - 154 Ωm −1 . Abiola et al. (2009) studied the groundwater potential and aquifer protective capacity of overburden units in Ado Ekiti. They delineated three groundwater potential zones (high, medium and low) and aquifer protective capacity (good, moderate and poor) in the study area. Yusuf et.al. (1982) used electrical resistivity survey and self potential methods to locate the most probable areas containing groundwater in sufficient quantity around Ajumawa village in Kano State. Ajayi and Hassan (1990) interpreted vertical electrical sounding (VES) data carried out at basement complex area in the western part of Kubanni Basin of Zaira, Nigeria and noted two to four geo-electrical layers with resistivities of these layers ranging about 14- 8000 Ωm −1 . The aquifers in this area were the weathered basement complex rocks. Dan-Hassan and Olorunfemi (1990) investigated the groundwater resources of Basement Complex of the North-Central Part of Kaduna State. From their survey, the Isopach map of the overburden shows that depth to the fresh basement varies from 4.3m- 64m and boreholes located within basement depression zones, which correspond to areas of relative thick overburden, give relatively high yields of 0.4 m 3 /s - 5.31m 3 /s. Bala (2001) used symbology (study of remote sensing imagery), a technique that differs from the conventional geophysical and geological methods, to delimit zones of fracture-controlled groundwater for exploration in the Wudil (Kano State) and its environs. Yaya et al. (2001) identified two major aquifer types in the crystalline basement complex rocks of Zamfara State, namely, the weathered overburden aquifer which rarely exceeds forty metres in thickness and fractured quartz/pegmatite vein aquifer which closes up with depth. They observed that the distribution of unsuccessful boreholes is fairly even and noted that the areas which are underlain by fresh and un-weathered granitic rocks tend to have greater borehole failure.

6 Olorunfemi (1990) carried out vertical electrical soundings and borehole investigations in two towns (a basement complex terrain) in Kwara State, and observed the overburden to be relatively thin at the valleys but significantly thick at the slope and ridge top. He concluded that saturated overburden thickness could be significantly high at slope/ridge top and groundwater yield could be higher at slope/ridge top than in the valley. Olayinka (1990) conducted an exploration for groundwater near Egbeda-Kabba, Kwara State using electromagnetic profiling and resistivity soundings. He observed that the depth to bedrock in the area is generally less than 40m but that three out of four boreholes drilled were very productive. Adekeye (2001) concluded in his work that the aquifers of the Basement Complex rocks in Kwara State are localized and discontinuous, essentially unconfined to semi confined and under water table conditions. Dan-Hassan (2001) from an interpretation of electrical resistivity survey (ERS) data and borehole lithologic logs was able to correlate the subsurface layers with their respective resistivities. He concluded that the aquifers of the Basement Complex rocks of north central Nigeria are predominantly weathered overburden aquifers. Eduvie and Olabode (2001) used analytical relationships to determine aquifer parameters from electrical resistivity survey (VES) data. They concluded that groundwater potentials of Basement Complex rocks is not a function of overburden thickness alone but a function of the three geo-electrical parameters: fractured bedrock resistivity, weathered layer’s resistivity and depth to bedrock. Eduvie et al. (2003) studied the groundwater potentials of Abuja and its environs. Borehole yields in the area vary from 0.8 to 7.2m 3 /hr. The areas of high potentials within the Federal Capital Territory are Kubwa, Jabi/Idu, Asokoro, Gwarinpa and Lugbe. The other zones characterized with thin overburden and lack of fractures has low groundwater potentials. Woodruff et.al. (1972) studied the groundwater resources of the University of Delaware (U.S.A.) and its environs, an area that is underlain by both Basement Complex rocks and sedimentary rocks. A potential groundwater yield of about 500gpm was estimated from a borehole in the Piedmont province underlain by metamorphic rocks. This high yield was attributed to secondary fracturing of the basement rocks. They reported that hard rocks of the Piedmont generally yield smaller and unpredictable amounts of water than do the coastal plain rocks. According to them, the difference in the yield of the two areas is as a result of the poor permeability of the crystalline rocks of Piedmont.

7 Flores-Marques et al. (2001) used electromagnetic survey (EM) and vertical electrical sounding (VES) to characterize the Etla Valley (Oaxaca, Mexico) aquifers. The VES profiles showed an aquifer basically containing sands, boulders, gravels and alluvium overlying a clay stratum that behaves hydraulically as the seal of the first aquifer (aquitard). The thirty-four EM observations showed that the vadoze zone averages twenty metres (20m) in thickness. Deep and shallow horizons suggested the presence of a second aquifer underlying a saturated-clay layer. A contamination plume with extremely high resistivity values was observed in the southern section of the mapped area. This feature seamed to disperse towards the northern portion of the valley, where the main water wells are located. Seaton (2002) revealed that the groundwater storage in the Blue Ridge Province (U.S.A.) is in the porous regoliths. Within the crystalline bedrock of the province, there is an anomalous lower resistivity interval associated with ancient fault shear zones. These shear zones and the brecciate rock adjacent to the shear zones can be hydraulically conductive and serve as pathways for groundwater movement. From the aquifer testing carried out, he observed a limited communication between the shallow and deeper bedrock aquifers.

CHAPTER TWO GEOLOGY AND HYDROGEOLOGY The regional geology of the study area and the hydrogeology of basement complex areas are discussed below. 2.1 Regional Geological Setting Geochronology and Evolution of the Basement Complex of southwestern Nigeria Although different authors had proposed different evolution models of the Basement Complex of the south-western Nigeria, there are three points on which the different authors have agreed. First, that the rocks of the basement complex comprise largely meta- sedimentary series. Those rocks have associated minor meta-igneous rocks, which have been variably altered to migmatite gneisses and older granitic rocks of both intrusive and replacement origin. Second, that the age of the Basement Complex rocks are Precambrian and, third, that the un-metamorphosed cross cutting dolerite and syenitic dykes are the youngest rocks of the Basement Complex. Rahaman (1971and1973) concluded that the Nigeria Basement Complex consists of five main rock groups. He classified them in relation to their relative age as follows: Un-metamorphosed dolerite dyke (youngest) Older Granite Charnockitic rocks Slightly migmatised to un-migmatised Para schist and meta-igneous rocks Migmatite –gneiss complex (oldest). The Migmatite Gneiss Complex The migmatite complex comprises biotite and biotite hornblende gneiss, quartzites and quartz schist and small lenses of calc-silicate rocks; this is most widespread in the southwestern Nigerian Basement Complex (Rahaman, 1989). The gneiss is classified into early, mafic and granitic components. Mineralogically, the early gneiss is granodioritic to quartz dioritic in composition. It is characterized by fine banding of alternating mafic and quartzo-feldspathic material. The contact between the mafic and felsic material is gradational. Typical of the early gneiss is found in Iseyin and Ibadan in Oyo state. The second component the mafic-ultramafic bands, is usually made up of amphibolites, biotite and biotite hornblende schists. Unlike the early gneiss which is gray- foliated, the mafic component is strongly foliated and its structure is parallel to those of the host rock. The last component- the light granitic or felsic component is usually granitic to

9 pegmatitic. According to Rahaman (1989) the three components described above may be observed in one outcrop. Different types of gneisses have been described which include banded gneiss, granite gneiss, transition gneiss, agmatite, augen, veined, porphyroblastic and cataclastic gneisses (Rahaman, 1989). Mineralogically, the gneiss is in general biotite and biotite hornblende gneiss. Plagioclase feldspar and quartz are dominanat minerals whereas pyroxene rarely occurs. The quartzite consists of at most eight minerals. Quartz is usually the dominant mineral, more than ninety percent, with minor amounts of muscovite, sillimanite, staurolite, gernet, hematite, graphite, tourmaline and zircon. Clionpyroxene, tremolite, actinolite, actinolite, epidote, calcite and sphene have been described from a quartzite from Iseyin (Rahaman, 1989). The occurrence in Iseyin lies along its strike between quartzite to the south and calci-silicate rocks thought to be derived from calcareous siltstones to the north (Rahaman, 1973). Calc-silicate rocks and marble outcrop as low-lying bodies in the migmatite gneisses of the Basement Complex. They usually continue for only a few metres.

Slightly Migmatised to Unmigmatised Paraschist and Metaigneous Rocks This group of rocks is clearly observed at the Efon Psammite Formation, the Igarra and Kabba Jakura Formation, and Iseyin Formation. De Swardt (1953) Hubbard et al.(1966) Dempster (1967) described the Effon Psammite Formation as a belt of quartzite, quartz schists and granulites which occurs largely at east of Ilesha and runs for one hundred and eighty (180) kilometers in a general NNE-SSW direction. Among the lithologies described are epidiorites, amphibolites schist and talcose rocks and those rocks are said to be possibly volcanic in origin. Eugeosynclinal environment of deposition was suggested for these rocks because of the association of volcanic and clastic rocks. The Igarra Formation runs for about sixty kilometers in a general NNW-SSW direction. The rock types present include polymict metaconglomerates, marbles, calcsilicate rocks, quartzites, politic schists largely quart-biotite schists. The Politic schists in places form impressive continuous ridges, the crests of which are made of narrow bands of quartzite. The metaconglomerate contains pebbles of quartz, granitic rocks, calc-silicate rocks and amphibolitic rocks. Marbles occurrences of economic value have been reported and are being exploited at Jakura, Igbetti, and Ukpilla. Smaller occurrences near the Ogbo River were discovered by Jones and Hockey (1964). Most recent exploitation of this mineral is at Obajana, near Kabba. The marbles are of varying colours:

10 white, grayish, green and pale greenish types have been described. The marble is composed predominantly of calcite with minor amounts of graphite and cal-silicate minerals. Charnockite Rocks The charnockites are rocks which are composed of quartz, alkali feldspar, plagioclase, orthopyroxene, clinopyroxene, hornblende, and biotite and accessory amounts of apatite, zircon and allanite. The alkali feldspar are mesoperthitic and zonal. Plagioclase feldspars on the other hand have composition in the andesine range with subordinate oligoclase but some have composition in the andesine –labrodiorite range such as those of Otun-Egosi area (Cooray, 1972c). Randomly oriented inclusions of various rock types occur within the charnockite bodies. Finely foliated amphibolites inclusions are common in the charnockite occurrences at Osuntedo, Awo, Ara and Oke-Patara. Xenoliths of concocted schist granulites and occurrence of a calc-silicate rock have also been found within the Oke-Patara charnockite. Foliated syenite bodies occur within the Osuntedo Charnockite. The charnockite has three major modes of occurrence. It occurs as core of an aureole of granite rocks, along the margins of Older Granite bodies and as discrete individual bodies in the gneiss complex. The first type is found at Wasimi, Oke-Patara and Idanre. A complete section is found at Wasimi, where a central area of charnockite is followed outwards by granodiorite porphyritic biotite and biotite hornblende granite and finally migmatite. Charnockite occurring along margins of Older Granite bodies especially porphyritic biotite and biotite hornblende granites are found in north of Akure, west of Egosi and south of Otun. The discrete individual bodies in the gneiss complex are found occurring at Lagun, Awo and Osuntedo and east of the Igarra Formation. The contact relationship of the charnockite to the surrounding rocks is variable. Gradational contact was observed between the Wasimi charnockite and the surrounding Older Granite rocks. This is marked by the loss of dark colouration which characterizes the feldspars of the charnockite, and the development of spots of hornblende in the surrounding hornblende granodiorite (Hubbard et al., 1968). Charnockites around Iwo show abrupt contacts with the surrounding country rocks. At Akure and Ifaki, the charnockites show cross cutting intrusive contacts with the surrounding rocks (Rahaman, 1989).

Bauchite Bauchite has a distinctive physical property and was first described from Bauchi in northern Nigeria by Oyawoye (1961). Typically, the rock is extremely coarse with feldspars in matrix of ferromagnesian plagioclase and quartz. Fayalite is the distinguishing mineral and

11 compositionally, the rock is a quartz monzonite (Oyawoye and Makunjuola, 1972). In southwestern Nigeria, bauchite has been found in Ewu, Ikarre and Ado-Ekiti all within charnockites body. Other occurrences include Araromi-Iyin southwest of Ado-Ekiti, south of Ondo on Ondo-Ore road: these were found to be surrounded by porphyritic Older Granite.

Older Granite The Older Granites include rocks of a wide range of composition: granite, granodiorites, adamallite, quartz monzonites, syenites, and pegmatite. They range in size from plutons to batholiths. In the schist environments, Older Granites occur in a circular to elliptical bodies while in the migmatite –gneiss terrain, they occur as elongated bodies (Rahaman, 1989). Jones and Hockey (1964) recognized three main groups of granites: early, main, and late phases. The early phase comprises granodiorites and quartz diorites. The main phase consists of coarse porphyritic biotite granite. The late phase consists of homogeneous granite and dykes, and pegmatite and aplites. The most abundant and the most typical member of the Older Granite suite is coarse porphyritic granite which has been described by Oyawoye (1972) as porphyroblastic granite. Most Older Granites possess a foliation which is concordant with that in the country rocks defined by the parallelism of the large feldspars and an alignment of the mafic minerals. The foliation tends to be better developed along the margins of the body than in the centre, as found in Akoko Older Granites and Okeiho and Iwo potassic syenites. In Igarra granite however, the alignment is weaker along the margin than in the centre. Inclusions of varying sizes and compositions occur within the Older Granites. Ovoid shaped inclusions of dark granulitic material varying in size from an inch to a metre or more are common. They (inclusions) commonly exhibit a vague outline, uniform appearance and contain smaller and fewer crystals of large feldspars than the enclosing granite. Inclusions of the surrounding country rocks have been observed such as the occurrence of garnet mica schist, calc-silicate rocks, and quartzite in the Igarra granite. The contact relationship of Older Granite with the surrounding country rock may either be abrupt or gradational (Rahaman, 1989).

Minor Rocks Minor rock types described by Rahaman, 1989 include the following, pegmatite, quartz vein, and dolerite vein. Pegmatite composed of microcline and quartz and typically

12 extremely coarse grained and showing great variation in grain size is widespread throughout the Basement Complex of southwestern Nigeria. Except in the area of slightly migmatised to unmagmatised paraschists and meta-igneous rocks, pegmatite is found to be associated with other rock types. The complex pegmatite at Ijero-Ekiti outcrops as Iwo hills. On the basis of textural and mineralogical variations, four zones have been distinguished within this body. The border zone is found to be composed of fine-grained quartz and tourmaline, while the outer wall zone is made up of crystals of tourmaline quartz feldspar, garnet and mica. The intermediate zone contains beryl and cassiterite with minor amounts of columbite, tantalite, and muscovite. The core, innermost zone is un-mineralized (barren) and consists of big quartz boulders. The contact between pegmatite and host rock may be microscopically sharp or diffuse, transitional and “replacive” (Rahaman, 1989). Quartz dykes and lenses occur in all minor rock types of the Basement Complex. They vary in thickness from a few millimeters to about a metre. Plates of muscovite and biotites at times may be found associated with large quartz dykes (Rahaman, 1989). While most of quartz dykes are strucureless and discondant with respect to the host rocks, some lie conformable with the host rock and have been involved in the tectonic activities affecting the host rocks. Dolerite dykes are described by some authors as the youngest member of the Basement Complex. They are tabular, un-metamorphosed bodies cross cutting the foliation in the host rocks. Dolerite dykes range from few millimeters to half a metre. The general trend of all dykes observed in the field is between NE-SW and ENE-WSW (Jones and Hockey, 1964; Freeth, 1971, Rahaman, 1973). The rock is composed of augite and plagioclase (andesine–labrodiorite) and is generally black, although some cases of pale green spots of olivine have been observed in hand specimen. They are fine grained and texturally dibasic. The contact between dolerite dykes and the host rock is always sharp and chilled.

Structural Elements of the Southwestern Basement Complex Foliation : This structure is observed virtually in all the major rock types of the Basement Complex. It occurs as parallel layer consisting of alternating dark and light minerals in the gneisses. In the quartzite, the quartzitic component bands can be peeled off along micaceous laminae parallel to the lithologic banding. Foliation in the schist belts is very characteristic and is termed schistocity. Rahaman, 1989 defined it as alignment of mica amphiboles and compositional banding. In the South-Western Nigeria Basement Complex, foliation is almost in a N-S direction with variation between NW-SE and NE- SW. In east of

13 Igarra Formation, the dominant trend of foliation is NW-SE, while in the Iwo and Effon Psammite Formations it is NNE-SSW direction. Foliation in the Basement Complex of southwestern Nigeria is of tectonic origin as evident by the presence of small, tight to isoclinal folds on the straight limbs of the folds, crescent-shaped attenuated closure, and rootless folds. These represent relicts of earlier folds and the large scale lithologic banding. Foliation is almost not exactly coincident (Rahaman, 1973). Lineation is a preferred alignment and orientation of minerals in rocks such as biotite, amphibolites and quartz. Lineation could also be described as the corrugation of the foliation by the crests and trough of minor folds, giving rise to a crenulations foliation. Folds : two types of folds are described by Rahaman (1989) for the South-Western Nigeria Basement Complex Rocks - the minor and major folds. Two types of the minor folds were observed in Iseyin area by Rahaman (1989). These are very common structures in the gneisses and schists. Three prominent major folds are outlined by the quartzite. In the first two quartzites, the outcrop patterns suggest the folds to be open with northeast-southwest trends, which are overturned to the west. The outcrop pattern of the third quartzite suggests the fold to be a refolded fold with the axial plane trace of the second folds being NW-SE. Eastward of Igarra Formation, the major fold between Otuo and Ikao is an antiform. Folding is open-to-close in style, and overturned to the east. Rahaman (1973) has shown that the major structure in the Iseyin area is a synform plunging northwards. Jones and Hockey (1964) concluded that the fundamental structure of the western part of South-Western Nigeria is an anticlinorium, with a northward plunging migmatitic core. Faults : Major faulting is not evident in the South-Western Nigerian Basement Complex Rocks. Most of those recognized are from aerial photographs. Jones and Hockey (1964) concluded that ENE-NE faults were results of post Older Granite tectonic activities.

2.2 Regional Hydrogeological Setting The mean annual rainfall ranges from 50.8cm in the most arid areas 152.4cm in the wetter areas of the southwestern Nigeria. The major rivers which drain the region are Rivers Shasha, Owena, Ona, Oshun, Oyi, Ogun and Yewa (Olayinka, 1971). Groundwater occurs in fractures, cracks and fissures of the crystalline rocks. Buried ancient alluvial channels are very common in the Basement Complex areas of southwestern Nigeria. Yields measured from boreholes vary between 1320 and 5760gal/day and specific yields estimated range from 54gal/hr/ft to 9.9gal/hr/ft. The water is generally acidic, and moderately hard. The absorbed oxygen demand, a measure of the amount of decaying organic

14 matter in the water, of surface water sources are generally higher than those of groundwater (Olayinka, 1971).

2.3 Local Geology The Egbe and Mopa-Amuro district which is the study area is underlain by bedrock of PreCambrian Crystalline Basement Complex comprising migmatite gneiss, older granite and isolated blocky mounds. Gniesses and migmatite gneiss are however dominant. The rocks are broadly oriented North-South and marked by a sub-parallel alignment of elongated and closely packed feldspar phenocrysts, mainly microcline and a corresponding preferred orientation of biotite mica and iron minerals (Mev Hydrosearch, 2001). Medium to coarse grained granite occurs as large pavement but discrete bodies with variable shapes intruding the main biotite granite, migmatite gneiss with quartzite. The migmaties are impregnated by numerous pegmatite and quart-feldspartic veins and capped with laterites. Granite-gneiss, porphyroblastic and biotite-hornblende granites, granitic pegmatites, amphibotised gabbros (metagabbros) and metamorphosed sediments constitute the predominant rock exposed in the basement terrain around Egbe. Other ampibolites in the area appear to have been derived from possibly basaltic rocks including tuffaceous materials. The metasediments consist of quartzites and quartzite schists derived from clastic, predominantly arenaceous sediments, and calc-silicate rocks derived from more carbonate-rich sedimentary facies (Bafor, 1981). Locally the amphibolitised gabbros show relict cumululate texture and on the whole the rocks have survived remarkably well, the granitisation which post-dated their formation (Bafor, 1981).

2.4 Local Hydrogeology The areas of Yagba-West and Mopa-Amuro Local Government Areas are generally drained by the River Kampe and its main tributaries of rivers Erigi, Ebba, Oyi and Ahuru. River Kampe is in turn a major tributary to River Niger. The catchment area has a record of mean annual precipitation of 1375mm, evapotranspiration of 1375mm leaving a water balance of only 9mm as runoff in the groundwater storage equation. The groundwater resource is contained in the weathered and or fractured basement rocks. Groundwater discharge is mainly through hand dug wells, boreholes, springs (usually during raining season when water table is very close to the surface) and discharge into streams and rivers. Recharge of the groundwater resource is mainly via precipitation and through rivers.

CHAPTER THREE METHODS OF STUDY The study was approached from three angles, via, geological, geophysical, and hydrogeological. 3. 1 Geological Investigation The geological investigation involved an initial desktop study of topographic maps (Isanlu, Sheet 225 and Aiyegunle, Sheet 226, which cover the study area) on a scale of 1:50,000. The study area was then gridded into six quadrants for easy geologic mapping which consisted of reconnaissance and detailed mapping of outcrops and other rock exposures along streams, rivers and road cuts. The geographic position (longitude and latitude) and elevation above mean sea level of each outcrop was determined using geographic positioning system (GPS). The features of an outcrop that were studied and described include rock type, texture and structures (joints and faults). A geological map was produced from the results of the investigation (Figure 3).

3.2 Geophysical Method Six vertical electrical sounding were conducted using Schlumberger array (Figure 4) with current electrode spread of AB = 200m. This was complemented with seventy fpive vertical electrical soundings (VES) that were conducted by the Geo-exploration (Nig.) Associates, Ilorin, Kwara State for Lower River Niger Basin and Rural Development Authority, Ilorin, Kwara State. These data were interpreted using curve matching and computer iterated techniques. Figure 5 shows the locations of the geo-electric survey.

3.3 Hydro-geological Investigation Two hydrogeological approaches were employed, static water level measurement and pumping test data analysis. The static water level of over one hundred hand dug wells were measured using dipper along with their topographic elevation and coordinates (latitude and longitude) using Geographical Positioning System (GPS). The measurements were carried out at the peak of the dry season, from 28 th January to 27 th February, 2009. At this period the static water levels are at their lowest points when the most accurate static water levels are best measured. These measurements were to be used to construct static water level contour map and hydraulic head map. Pumping test data used were supplied by the Hydrogeology

Figure 3: Geological Map of the Study Area

Figure 4: Sketch Diagram of Schlumberger Array

Figure 5: Base Map of the Study Area Showing VES Stations

19 Department of Lower Niger River Basin and Rural Development Authority, Ilorin, Kwara State. Figure 6 shows the pumping test stations. A total of twenty water samples were collected from different water sources in the study area in January, 2009. Three water samples were collected from boreholes and seventeen from hand dug wells (Figure 7). All samples for physical measurement and chemical analysis were collected with fresh two-litre plastic containers. Temperature, conductivity, and PH were determined using HACH Portable PH/ISE meter. Colour, turbidity, suspended solids which are related parameters were determined with HACH DR/2000 spectrophotometer. The chemical parameters were determined using different apparatus and methods. The total hardness was determined using HACH Digital Titrator. Except chloride which was analyzed for using argentometry tetremetric method, all the other anions were determined using the HACH DR 2000 spectrophotometer. All the cations were determined using the atomic adsorption spectrophotometer (AAS) model 2005. The bacteriological analysis for E.coli and total bacteria was accomplished by the use of membrane filtration method.

3.4 Data Analysis Statistical analyses were performed using Software Packages for Social Sciences (SPSS) computer software. The statistical tests applied were correlation matrix and Principal Components Analysis. Data obtained from laboratory analysis were used as variable inputs for the statistical tests. Principal component analyses were performed on correlation matrix of the raw data in which a water samples is described by twenty eight parameters (physical, biological and chemical). The following computer soft wares were employed in the course of the study: Arc Map, Surfer 8, Corel Draw and Aqua-Chem. These were used in the contouring of the maps and drawing of the graphical presentations.

Figure 6: Base Map of the Study Area Showing Pumping Test Locations.

Figure 7: Base Map of the Study Area Showing Water Sample Locations

22 CHAPTER FOUR RESULTS AND DISCUSION 4.1 Local Geology and Groundwater Yield Table I is the result of local geology in the vicinity of borehole locations and the borehole yield. From the table, boreholes sited in areas underlain by granite, quartzite and pegmatite have higher yields than those sited within gneisses and schist. For example, the borehole at Okeere village which is underlain by pegmatite has a yield of 2.0l/s. In Egbe town and Ogga village yields of 2.5l/s and 2.0l/s respectively were measured from boreholes sited within porphyroblastic granite and quartzite and quartz schist. Low yields of 0.2l/s were measured from wells sited within migmatite gneiss and schist, and gneiss at Otafun village and Ogbom village respectively. The differences in yield are explained in terms of the weathered products from these rock types. Whereas granite, quartzite and pegmatite weather to a permeable-sand-rich product, gneiss and schist on the other hand give a clay-rich product that has poor permeability when weathered.

4.2 Static Water Level and Hydraulic Head: Groundwater Flow Directions The results of the measured well static water level, topographical elevation above mean sea level (amsl) and the computed hydraulic head are presented in Table 2. Detailed results of the static water levels and computed hydraulic head are presented in the Appendix 1. Figure 8 is the static water level map of the study area and it shows areas of equal static water level. The discontinuous nature of basement aquifer system is revealed by the variability in the static water level measured within a particular village/town. Hydraulic head of a well is obtained by subtracting the well’s static water level from its topography elevation above mean sea level and it is employed in determining the direction of groundwater flow. The computed hydraulic heads of all the sampled wells were used to generate the hydraulic head (Figure 9). The hydraulic head map reveals that the ground water flows from one diverging (radiating) zone named zone D (see Figure 9) into three converging (collecting) zones designated as zones A, B and C.

23 TABLE 1 Result of Borehole Yield and Static Water Level Location Local Geology VES Point Yield(l/s) Borehole S.W.L Number Pump Depth (m) (m) Tested Okeere Pegmatite 1 2.0 37.90 5.30 Egbe Porphyroblastic 1 2.5 45.43 6.50 Granite Oroke-Efo Granite 1 2.0 30.0 4.90 Amuro Orokere Granite 1 2.0 26.0 4.80 Amuro Ayede Porphyritic Granite NA NA NA NA Amuro and Augen Gneiss Agbajogun Quartz Granite 3 0.4 23.0 3.90 Amuro Ileteju-Mopa Granite 4 2.0 30.0 7.80 Odole-Mopa Migmatite Gneiss and 3 2.0 24.20 7.80 Granite Otafun Migmatite Gneiss and 3 0.2 16.60 3.80 Schist Takete Granite NA NA NA NA Igbaruku Metagabbro- NA NA NA NA amphibolite Iyamerin Metagabbro NA NA NA NA Odo-Ara Quartzite and Quartz- 3 2.0 30.60 6.42 Schist Ogbe Gneiss and Older NA NA NA NA Granite Ogbom Gneiss and Older 4 0.2 33.0 9.4 Granite Ogga Quartzite and Quartz 3 2.0 32.6 6.90 Schist

NA-not available 24

TABLE 2 Static Water Level and Hydraulic Head Location Number of Static water level Hydraulic Head Wells Range (m) Range (m) Ileteju 12 7.3-2.9 305.7-278.5 Odole-Mopa 8 7.1-3.1 312.4-287.1 Oroke Efo-Amuro 17 7.1-0.0 291.35-263.35 Agbajogun-Amuro 7 7.75-2.1 284.75-263.35 Otafun 1 Nil Nil Egbe 21 9.50-2.9 360.5-317.7 Okere 2 8.10-5.6 334.55-340.9 Takete 2 10.20-7.30 286.70-279.85 Ogbom 3 6.85-4.10 323.9-318.15 Ogga 5 6.30-4.20 277.85-243.7 Odo-Ara 2 6.25-0.0 270.75-264.00 Igbaruku 2 6.70-0.0 333.0-320.0 Ogbom 4 8.45-0.0 398.9-292.0 Ogbe 4 7.50-6.02 294.5-285.78 Okeagi 13 7.80-3.70 342.38-300.6

Figure 8: Static Water Level Map of the Study Area.

Figure 9: Hydraulic Head Model of the Study Area

27 4.3 Geo-Electrical Characterization General Features of the Vertical Electrical Sounding Curves The results of the interpreted vertical electrical soundings (VES) data are presented in Table 3. The interpreted vertical electrical sounding data show that the study area is characterized with 2-layer to 5-layer geo-electric sections. From the table, the two-layer geo- electric section is observed at Egbe, the three-layer type is observed at all the villages and towns except Takete, the four-layer type is observed in villages and towns such as Egbe, Takete, Ileteju Mopa e.t.c. and five-layer geo-electric section is noted at Egbe and Ogga. Twelve sounding curve types or signatures are observed namely H-type curve, A-type curve, HK-type curve, HA-type curve, KH-type curve, AK-type curve, AA-type curve, KQ-type curve, QH-type curve, HAH-type curve, KHK-type curve and QHK-type curve. Their frequencies of occurrence are shown in Figure 10. The H-type curve is characterized by a middle layer of lower resistivity than the overlying and underlying layers and it is always water saturated. It is revealed in this study that some of the zones classified later as medium groundwater potential zones are characterized with vertical electrical sounding H curve types. This can be observed in places such as Okeere and Otafun. The A-type curves are characterized by an increase in resistivity from the top soil to the bedrock and the middle layer is not water saturated as those of the H- type curves. For example Igbaruku and Ayede Amuro villages are characterized with A-curve type and are low groundwater potential zones (see Figure 36 and Appendix VI). The Subsurface Sequences Topsoil Layer From Table 3, the topsoil layer thickness ranges between 0.4m and 10.0m and this layer’s resistivity varies from 15.0 Ωm to 8787 Ωm . Thus the study area is characterized with variable topsoil thickness and resistivity and can be said to be generally thin. Figures 11 and 12 show respectively the spatial distributions of the topsoil thickness and resistivity of the study area. Weathered and Weathered/Fracture Layer The weathered layer is the second layer in a 3-layer geo-electric section and the third layer in 4-layer type. This layer constitutes the aquiferous unit. From Table 3, the weathered layer thickness ranges from 0.8m to 44.0m and with resistivity varying from 7.35 Ωm to 780 Ωm . High weathered layer thickness is observed at places such as Egbe (18.38m) Odole Mopa (28.18m) Otafun (37.52m) and Ogga (41.4m). Thin weathered layer is noted at villages such as Orokeke Amuro (1.4m) and Odole Mopa (0.68m). The weathered/fractured layer

TABLE 3: Layers’ Resistivities, Thicknesses and Curve Types

Location No. of Ist layer 2nd layer 3rd layer 4th layer 5th layer Observed layer type VES Thickness &Resistivity Thickness &Resistivity Thickness &Resistivity Thickness &Resistivity Thickness Range Range Range Range & Resistivity Range Okere 5 0.49-2.41m 2.71-16.32m ∞m Nil Nil 3- 110.2-1278.5 Ωm 37.71-110.96 Ωm 229.1-1047.7 Ωm Egbe 14 0.7-10.0m 0.74-11.77m 1.97-18.38m Nil Nil 2- Nil layer, 5layer 33.32-1741.58 Ωm 34.27-445.88 Ωm 82.4-744.13 Ωm 47-717 Ωm

Oroke Efo Amuro 5 0.62-1.69m 3.38-19.32m ∞m Nil Nil 3- 366.49-954.94 Ωm 72.76-992.17 Ωm 113.09-1712 Ωm Orokere Amuro 5 3.0-7.0m 2.0-9.6m 1.4-5.0m Nil 3- Nil 4- 18.0-205 Ωm 40.44-508.2 Ωm 264.6-1948.1 Ωm 484-899 Ωm Ayede Amuro 5 0.4-0.5m 0.2-2.6m 2.0-7.5m Nil Nil 3- 4- 20-180 Ωm 35.0-350 Ωm 90-22o Ωm 120-5000 Ωm Agbajogun Amuro 5 0.48-4.5m 2.57-18.19m Nil Nil Nil 3- 4- 126.58-765.28 Ωm 32.55-163.77 Ωm 101.12-510.5 Ωm Ileteju Mopa 5 1.31-5.43m 0.91-15.36m Nil Nil Nil 3- Nil 4- 110.09-370.63 Ωm 7.35-248.38 Ωm 88.91-597.37 Ωm Odole Mopa 5 0.63-1.20m 0.68-28.18m Nil Nil Nil 3- Nil Nil 5- 92.18-5422.99 Ωm 33.21-647.47 Ωm 417.19-751.8 Ωm Otafun 4 0.91-2.82m 3.32-37.52m Nil Nil Nil 3- 599-1070 Ωm 56.2-135.70 Ωm 403-16834 Ωm Takete 1 Nil Nil Nil Nil Nil 4- Igbaruku 5 8.0-9.0m 3-6m Nil Nil nil 3- 14-233 Ωm 41.89-82.7 Ωm 283-446.8 Ωm Iyamerin 2 2.7-5.0m 2.0-9.0m Nil Nil Nil 3- 97-296 Ωm 51-59.9 Ωm 258.1-272 Ωm Odo-Ara 5 0.9-2.7m 6.7-12.3m Nil Nil Nil 3- 15-38 Ωm 5.0-53 Ωm 160-286 Ωm Ogbe 5 1.1-1.4m 4.2-10.2m Nil Nil Nil 3- 95-170 Ωm 50.0-93.0 Ωm 625-1500 Ωm Ogbom 5 0.9-1.5m 4.6-9.0m Nil Nil Nil 3- 1585-2500 130-460 Ωm 27-95 Ωm Ogga 5 0.6-1.1m 0.2-6.2m 2.3-41.4m Nil Nil 3- 4- 705-8787 Ωm 98-780 Ωm 133-5092 Ωm 71-2751 Ωm 5-

Frequency 20

H A K H K H K K HA H K AA A KQ Q AH H H KH Q Observed Curve Types

Figure 10: Frequency Distribution of Observed Curve Types in the Study Area

30 resistivity varies from 47.04 Ωm to 248 Ωm . The thickness of this layer is usually greater than 5.2m where it is underlain by fresh bedrock and has infinite thickness where it is the last observable geo-electric layer. Figures 13 and 14 show respectively places of equal weathered layer thickness and weathered layer resistivity. The Fresh Basement or Bedrock The depth to bedrock varies from 4.12m to 44.8m and the resistivity value of the bedrock varies from 208.36 Ωm to 16,834 Ωm in the study area. Low resistivity value of 229.10 Ωm and 208.36 Ωm are thought to reflect zones of fissuring within the basement.

4.4 Depth to Bedrock (Overburden Thickness) The depth to bedrock as the name implies, is the total thickness of all the overlying layers above the fresh basement rock. Thickest overburden is found around Ogga with an overburden thickness of 44.8m. Thinnest overburden is found around Okeere with overburden thickness of 4.12m. Overburden thickness is one of the parameters on which groundwater potential evaluation is based. Areas that are characterized with thin overburden are zones of probable low groundwater zones and those areas with thick overburden are zones of probable high groundwater zones. Figure 15 shows areas of equal overburden thickness in the study area.

4.5 Basement Relief Basement elevation of a place is obtained by subtracting overburden thickness from topographical elevation above mean sea level. The result of this estimation is presented in the Appendix IV. The results of the computations were used to contour the basement relief map of the study area (Figure 16). As shown in the figure the area is characterized with ridges and depressions. Areas of basement elevation in the range of 388m to 272m above mean sea level are classed as basement high (ridge) and those below 272m above mean sea level as basement low (depression). Two main ridges are observed, one on the western part of the study area covering towns and villages such as Egbe, Okeere, Iyamerin, Igbaruku, Ogga, Ogbom and Ogbe and the other on the eastern part covering a place like Otafun to the east. Three basement depressions are defined, one located north of Ogga and east of Odo-Ara, another covering places as Odole, Ileteju Mopa, Orokere and Ayede and the third covering Ayede Amuro in the east. High yields were measured from basement “low” or depression where saturated

Figure 11: Topsoil Thickness Map of Study Area

Figure 12: Topsoil Resistivity Map of the Study Area.

Figure 13: Weathered Layer Isopach Map of the Study Area.

Figure 14: Weathered Layer Isoresistivity Map of the Study Area.

Figure 15: Overburden Thickness Map of the Study Area.

Figure 16: Basement Relief Map of the Study Area.

overburden thickness is higher than at basement elevations such as rigde/slope top where saturated overburden thickness is thin. Yield of 2.5l/s and 2.0l/s were measured at a basement “low” in Egbe and Ileteju-Mopa respectively while a yield of 0.2l/s was measured at a basement ridge top in Otafun (see Table 1 and Figure 16).

4.6 Evaluation of Aquifer Protective Capacity Longitudinal conductance measured in mhos for each vertical electrical sounding station is used here for the evaluation of aquifer protective capacity of the study area. Aquifer protective capacity is the ability of the overburden unit to retard and filter percolating ground surface polluting fluid into the aquiferous unit. The total longitudinal conductance (S T ) of the overburden unit at each vertical electrical sounding station was obtained from the relation:

n hi S T = ∑ (Zohdy et al., 1974) (1) i=1 ρi

Where S T = total longitudinal conductance of the overburden

ρi = layer resistivity hi = layer thickness and n = number of layers. The computed longitudinal conductance and the longitudinal conductance and aquifer protective capacity rating model shown in Table 4 was used in the characterization of the study area with respect to aquifer protective capacity. A summary of the results of the computed longitudinal conductance/aquifer protective capacity for the eighty one vertical electrical sounding stations is presented in Table 5 with the detailed results shown in Appendix V. The table shows that 82% of the area is of poor aquifer protective capacity, 11% of the area is of moderate aquifer protective capacity and 7% of the area is of weak aquifer protective capacity. This rating summary is shown in Figure 17. Where weathered basement rock is rich in clay which is signified by low electrical resistivity value, the longitudinal conductance value is high and the aquifer protective capacity is classed a good. Fluids movement (contaminants transport) is almost impeded in a terrain or zone of good, very good and excellent aquifer protective rating whereas in areas of

TABLE 4 Longitudinal Conductance/Protective Capacity Rating (Henriet, 1976: Oladapo et al., 2004) Longitudinal Conductance(mhos) Protective Capacity Rating > 10 Excellent 5-10 Very Good 0.7-4.49 Good 0.2-0.69 Moderate 0.1-0.19 Weak < 0.1 Poor Adapted from Omoyoloye ( et al., 2008)

TABLE 5 Longitudinal Conductance and Aquifer Protective Capacity Location Number Longitudinal Type of Aquifer of VES Conductance Protective (mhos) Range Capacity Observed Okeere 5 0.0013-0.017 Poor

Egbe 12 0.0017-0.333 Poor, weak, moderate OrokeEfo 5 0.0019-0.0447 Poor Orokere 5 0.0265- Poor, weak 0.01679 Ayede 5 0.0187-0.0821 Poor Amuro Agbajogun 5 0.0022-0.3124 Poor, moderate Amuro Ileteju- 5 0.0038-0.2131 Poor, weak, Mopa moderate Odole- 5 0.0004-0.2068 Poor, moderate Mopa Otafun 4 0.00043-004 Poor Takete 1 Nil Poor Igbaruku 5 0.0429-0.5714 Poor Iyamerin 5 0.0169-0.0619 Poor Odo-Ara 5 0.013-0.0844 Poor Ogbe 5 0.0092-0.0116 Poor Ogbom 5 0.0024-0.0069 Poor Ogga 5 0.0001-0.0028 Poor

M oderate 11%

Weak 7%

Poor 82%

Figure 17: Aquifer Protective Capacity Rating

weak and poor aquifer protective capacity ratings, contaminants transport is barely restricted. The implication of this in this study is that, those areas characterized as weak and poor aquifer protective capacity zones are vulnerable to pollution of groundwater resources. Leakage from buried underground storage tanks (especially petroleum storage tanks in petrol filling stations), infiltration and percolation of leachates from decomposed open refuse dumps (non-sanitary landfills), line and diffuse pollutions from agricultural activities such as application of fertilizer and animal dumps would constitute sources of contaminations that

constitute threats to the subsurface water resources. A map of the aquifer protective capacity of the study area is shown as Figure 18.

4.7 Groundwater Potentials Evaluation Groundwater potential was carried out by comparing the following parameters: thickness and resistivity of weathered/fractured layer, overburden thickness, obtained from each vertical electrical sounding station and yield from the pumping test. Three groundwater zones were delineated namely high, medium and low groundwater potential zones following the models of Eduvie and Olabode (2001) (Tables 6 and 7). High groundwater potential zone is found only at Egbe with the zone this zone is characterized by HAH curve type, an overburden thickness of 22.35m, weathered layer thickness of 20.0m, weathered layer resistivity of 82.40 Ωm , bedrock resistivity of 556.92 Ωm and yield of 2.5l/s. Twenty two vertical electrical sounding stations classified as medium ground water potential zone with overburden thickness ranging from 10.2m to 44.8m, weathered layer thicknesses varying from 10.0m to 41.4m, weathered layer resistivity varying from 33.21 Ωm to 792.17 Ωm , bedrock resistivity varying from 110.65 to ∞Ωm and yield varying from 1.5l/s to 2.0l/s. This zone is observed at villages and towns such as Okere, Iluteju-Mopa, Egbe, Ogbe, Otafun e.t.c. Fifty eight vertical electrical stations showed low groundwater potential zone characterized by curve types A, H and HA. It is observed that all vertical electrical sounding stations with A- curve type are associated with low groundwater potential zone with electrical resistivity increasing from the top layer to the underlying layers. The low groundwater potential zone is found in all the villages and town except Ayede-Amuro, Igbaruku, Odo-Ara and Ogbom which are completely defined as low groundwater potential zones with overburden thickness ranging from 3.0m to 19.32m, weathered layer thickness

Figure 18: Aquifer Protective Capacity Map of the Study Area.

varying between 0.19m and 18.65m, weathered layer resistivity ranging from 5.0 Ωm to 744.13 Ωm , bedrock resistivity varying between 76 Ωm and ∞Ωm and yield less than 1.5l/s.

A map of the groundwater potential of the study area is shown as Figure 19. Details of the classification of all the eighty one vertical electrical sounding stations are presented in a tabular form in the Appendix 6. Results of the relationship between aquifer protective capacity and groundwater potential in the study area show inverse trend. Whereas aquifer protective capacity which is dependent on thickness and resistivity of overburden unit increases as the resistivity decreases (increase in clay content) groundwater potential decreases as the resistivity decreases (increase in clay content). This inverse relationship is obvious where aquifer protective capacity is of “moderate rating” and where groundwater potential is of “high and medium ratings” (compare Appendices 5 and 6). For example in locations such as Okere, Egbe, Orokere, Agbajogun, Odole Mopa, Otafun, Iyamerin, Ogbe, and Ogga, the high and medium groundwater potential zones correspond to poor and weak aquifer protective capacity zones . Also in villages and towns such as Igbaruku, Odole Mopa, Ilteju Mopa, Agbajogun Amuro and Egbe, the medium aquifer protective capacity is found to correspond to zones of low groundwater potential.

4.8 Groundwater Quailty and Hydrogeochemistry The results of the hydrochemical analyses are presented in Tables 8 to 11. From the results of the analyses, pH values range from 7.46 to 8.70. According to World Health Organization, 1993, an optimum pH range of 6.5 to 8.5 has been set as standard for drinking water. Only two of the water samples, samples taken from Ileteju I and Oroke-Efo Amuro with respective pH values of 8.60 and 8.70, are above the WHO, 1993 drinking standard. A pH of greater than 9 is considered too high as chlorination (a purification technique) will be ineffective because some of the chlorine will try to restore the pH to neutral. From the results obtain in this study all the water samples are capable of being treated using chlorination where necessary. The water samples analyzed showed temperature range value of 28 0C to 29.5 0C . The Standard Organization of Nigeria (SON, 2007) guideline value for drinking water is

TABLE 6 Aquifer Potential as a Function of Weathered layer Thickness and Resistivity Weathered Weathered Yield Aquifer Potential layer layer (l/s) Characteristics Thickness Resistivity (m) ( Ωm ) <10 <20 <1.5 Clays with much clay and limited Very Low potential >25 21-100 ≥ 2.5l/s Optimum weathering and good High groundwater potential 10-25 101-150 1.5- Medium conditions of weathering Medium 2.49 And medium potential <10 151-300 1.5 Little weathering and poor potential Low <10 >300 <1.5 Negligible potential Negligible Adapted from Eduvie and Olabode (2001)

TABLE 7 Aquifer Potential as a Function of Depth to Bedrock and Bedrock Resistivity Depth to Bedrock resistivity Aquifer Potential Bedrock (m) ( Ωm ) Characteristics <10 >3000 Little or no fracturing of the Very low bedrock; negligigble potential 10-20 1500-3000 Fairly low effect of fracturing; Low low aquifer potential 20-30 750-1500 Reduce influence of fracture. Medium Medium aquifer potential >30 <750 High fracture/permeability as a result High of fracturing. High aquifer potential. Adapted from Eduvie and olabode (2001).

Figure 19: Groundwater Potential Map of the Study Area.

TABLE 8 Physical and Biological Parameters Location Source Temp. pH Colour Turbidity Total Faecal ( 0C ) (Pt.Co) (FTU) Bacteria/100ml Coliform/100ml Otafun Well 27.0 7.88 660 85 4.0 0.0

Takete Well 29.0 7.83 176 0.0 0.0 0.0 Ogga Well 28.0 7.75 180 29 1.8 1.0 Ileteju Borehole 29.0 8.60 80.0 3.2 0.0 0.0 Mopa I Agbajog Well 27.0 8.35 95.0 39 5.2 3.4 u Amuro Oroke Well 29.0 8.70 247 62 1.0 9.0 Amuro Okeagi Borehole 28.0 8.39 40.0 1.0 2.1 2.0 Odo-Ara Well 29.0 7.80 204 17 5.0 2.0 Igbaruku Well 28.0 8.17 327 11 3.0 2.0 Ogbe Well 28.5 8.14 92.0 3.0 3.0 2.1 Egbe I Well 29.0 7.45 30.0 3.0 0.0 0.0 Ogbom Well 29.0 8.11 69.0 12 2.0 3.0 Egbe II Well 28.0 8.10 81.0 17 8.0 3.0 Ayede Well 29.5 7.78 30.0 1.0 0.0 0.0 Odole Well 28.0 8.24 85.0 12 0.0 0.0 Okere Borehole 29.0 8.33 35.0 0.0 1.0 0.0 Ileteju II Well 28.5 8.29 0.0 0.0 3.6 2.3 Egbe III Well 28.5 7.46 0.0 0.0 5.0 4.3 Ileteju Well 28.0 8.40 0.0 0.0 4.0 1.0 III Egbe IV Well 28.0 8.44 0.0 0.0 4.0 1.0

TABLE 9 Chemical Parameters Location Source EC TDS TSS TS TH CaH MgH µscm −1 (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) Otafun Well 441.3 286.78 38 324.78 56 50 6.0 Takete Well 442.5 287.63 9.0 296.07 96 80 16

Ogga Well 280.1 182.07 30 212.59 102 70 32 Ileteju Borehole 300.9 195.59 22 217.59 98 80 18 Mopa Agbajogu Well 200.6 130.39 20 150.39 86 70 16 Amuro Oroke Well 300.3 195.2 78 273.2 110 76 34 Amuro Okeagi Borehole 672.2 436.93 45 481.93 236 176 60 Odo-Ara Well 90.1 58.57 8.0 66.57 36 30 6.0 Igbaruku Well 421.0 273.65 13 286.65 182 100 82 Ogbe Well 521.7 339.11 15 354.11 192 102 90 Egbe Well 161.2 104.78 12 116.5 76 60 16 Ogbom Well 522.8 339.82 17 356.82 188 110 78 Egbe Well 241.2 156.78 15 171.78 100 62 38 Ayede Well 140.2 91.13 0.0 91.13 54 50 4.0 Odole Well 579.2 376.48 39 415.48 256 180 76 Okere Borehole 377.9 245.64 0.0 245.64 130 86 44 Ileteju Well 599.7 389.81 0.0 389.81 184 122 62 Egbe Well 138.9 90.29 0.0 90.29 52 46 6.0 Ileteju Well 477.7 310.51 0.0 310.51 166 102 64 Egbe Well 376.5 244.73 0.0 244.73 156 92 64

TABLE 10 Cations and Anions S/N Sour Ca Mg Fe Na K + SO Cl HC NO PO CO OH S ce 2+ 2+ 2+ + −2 − − − −3 −2 − A (mg 4 O 3 3 4 3 (m (m (m (mg /l) (m (m (mg (m (m (m (m R g/l) g/l) g/l) /l) g/l) g/l) /l) g/l) g/l) g/l) g/l)

Otafu Well 20. 1.4 0.5 33. 18. 10 32 10 64. 0.1 0.0 0.0 1. n 0 7 7 149 665 28 9 93 Taket Well 32. 3.9 0.0 39. 28. 22 38 25 67. 0.2 0.0 0.0 1. e 0 1 0 816 739 32 2 31 Ogga Well 28. 7.8 0.1 29. 21. 14 22 25 58. 0.1 0.0 0.0 1. 0 1 2 113 061 52 8 72 Iletej Bore 32. 4.3 0.0 34. 17. 15 10 105 22. 0.5 20. 0.0 0. u hole 0 9 2 609 395 44 2 0 85 Mopa Agbaj Well 28. 3.9 0.0 33. 16. 3.0 12 75 10. 0.1 50 0.0 1. ogu 0 0 3 051 115 12 3 55 Amur o Orok Well 30. 8.3 0.1 48. 20. 2.0 12 35 15. 0.1 30 0.0 2. e 4 0 4 631 921 40 8 02 Amur o Okea Bore 70. 14. 0.0 56. 21. 41 64 130 54. 0.2 30 0.0 1. gi hole 4 65 3 118 173 12 8 59 Odo- Well 12. 1.4 0.1 17. 9.0 0.0 18 60 20. 0.0 0.0 0.0 1. Ara 0 7 2 095 95 68 8 24 Igbar Well 40. 20. 0.0 52. 24. 10 24 175 26. 0.3 30 0.0 1. uku 0 02 7 165 118 84 1 68 Ogbe Well 40. 21. 0.0 50. 20. 40 32 120 34. 0.1 20 0.0 1. 8 97 7 056 732 76 8 57 Egbe Well 24. 3.9 0.0 31. 13. 0.0 24 55 36. 0.1 0.0 0.0 1. 0 0 6 198 095 96 0 16 Ogbo Well 44. 19. 0.1 51. 16. 21 48 60 68. 0.1 40 0.0 1. m 0 04 2 067 115 20 5 62 Egbe Well 24. 9.2 0.0 42. 24. 6.0 10 50 34. 0.2 0.0 0.0 1. 8 8 2 156 095 32 2 83

Ayed Well 20. 0.9 0.0 26. 12. 0.0 18 25 35. 0.2 0.0 0.0 1. e 0 7 6 913 619 20 9 60 Odole Well 52. 18. 0.1 56. 24. 28 50 90 42. 0.3 20 0.0 1. 2 16 7 089 082 24 4 70 Okere Bore 34. 10. 0.0 40. 21. 27 32 130 21. 0.3 20 0.0 1. hole 4 74 8 067 211 12 4 19 Iletej Well 48. 15. 0.0 51. 14. 6.0 52 0.0 49. 0.1 100 0.0 1. u 8 14 7 156 698 12 6 64 Egbe Well 18. 1.4 0.1 26. 19. 0.0 22 60 16. 0.0 0.0 0.0 1. 4 7 0 115 400 28 8 15 Iletej Well 40. 15. 0.0 52. 16. 10 20 160 14. 0.1 40 0.0 1. u 8 63 1 986 332 08 7 41 Egbe Well 36. 15. 0.0 32. 11. 0.0 20 110 30. 0.3 40 0.0 1. 8 63 9 517 091 80 6 13 SON 75 50 0.3 200 250 250 250 50. (1993 0 ) EU(1 250 50. 998) 0

TABLE 11 Heavy metals Location Source As + (mg/l) Pb 2+ (mg/l) Cd 2+ (mg/l) Cr 3+ (mg/l) Mn 2+ (mg/l) Otafun Well 0.010 0.011 0.019 0.121 0.0381 Takete Well 0.008 0.000 0.005 0.063 0.0514 Ogga Well 0.011 0.006 0.021 0.161 0.2218

Ileteju Mopa Borehole 0.007 0.000 0.009 0.005 0.0598 Agbajogu Well 0.006 0.000 0.002 0.003 0.0665 Oroke Amur Well 0.011 0.009 0.026 0.165 0.0902 Okeagi Borehole 0.011 0.014 0.033 0.215 0.0121 Odo-Ara Well 0.010 0.007 0.018 0.096 0.0755 Igbaruku Well 0.008 0.009 0.001 0.017 0.0198 Ogbe Well 0.009 0.013 0.014 0.158 0.0124 Egbe Well 0.008 0.022 0.017 0.202 0.0653 Ogbom Well 0.008 0.006 0.002 0.0699 0.0653 Egbe Well 0.005 0.000 0.000 0.034 0.0119 Ayede Well 0.007 0.004 0.006 0.051 0.0011 Odole Well 0.005 0.000 0.000 0.005 0.0903 Okere Borehole 0.010 0.009 0.011 0.118 0.0294 Ileteju Well 0.008 0.007 0.005 0.006 0.0538 Egbe Well 0.009 0.005 0.003 0.105 0.0083 Ileteju Well 0.006 0.000 0.000 0.032 0.0018 Egbe Well 0.004 0.000 0.000 0.000 0.0657 WHO(1993) 0.01 0.01 0.003 0.05 0.10 EU (1998) 0.01 0.01 0.005 0.05 0.05 SON (2007) 0.01 0.01 0.003 0.05 0.200

25 0C . All the water samples could be regarded to be high temperature water. The temperature of water is an essential physical parameter; low temperature water is generally more potable than warm water. High water temperature enhances the growth of microorganisms. It is noted that apart from water samples taken from Takete, Egbe I, Ayede Amuro and Odole Mopa, all the other water samples showed contamination from total bacterial and faecal coliform. Turbidity values range between 85.0FTU and 0.0FTU. There is neither acceptable

limit nor maximum permissible limit for this parameter in the WHO, (1993) guideline values. Water with high turbidity value is often associated with micro-organisms (bacteria) contamination. For instance, water sample from Otafun has turbidity of 85FTU and total bacteria concentration of 4.0/100ml and that from Oroke Efo Amuro has a turbidity value of 62FTU and total bacteria and faecal coliform concentrations of 1.0/100ml and 9.0/100ml respectively. On the other hand, water sample from Takete has a low turbidity value of 0.0FTU and 0.0/100ml concentration of both total bacteria and faecal coliform. It should be noted that all the water samples that showed high turbidity were collected from hand dugs wells. Since some of these wells may be tapping from the overburden the high turbidity may be resulting from the clayey overburden. The two biological parameters analyzed for are total bacterial and faecal coliform. The results reveal that the concentration of total bacteria and faecal coliform in the water samples range between 0.0-8.0/100ml and 0.0-9.0/100ml respectively. The WHO, 1993 maximum permitted levels of these microorganisms (total bacteria and faecal coliform) in drinking must not exceed 0.0/100ml. Comparing this standard with the results, only water samples from Takete, Ileteju (I), Egbe (I), Ayede Amuro and Odole have their total bacterial and faecal coliform concentrations within the WHO (1993) standard guide line value (0.0/100ml). The possible causes of this contamination in the study area are poor human well usage practices such as leaving wells uncovered, poor hygiene practices around wells e.t.c. The values for TDS ranged from 58.57mg/l to 436.93mg/l with a mean of 214.62mg/l. WHO, 1993 has a standard guideline value of 1000mg/l for TDS. At the same time, water with extremely low concentrations of TDS, such as that from Odo-Ara with 58.57mg/l may be unacceptable because of its flat, insipid taste (WHO, 2006). Hardness (as calcium hardness) in the water samples analyzed range from 30mg/l to 180mg/l. Standard Organization of Nigeria (SON, 2007) set a maximum permissible value of 150mg/l for hardness (calcium carbonate hardness). Two of the water samples, one from Okeagi and the other from Odole with respective hardness values of 176mg/l and 180mg/l are above the SON, (2007) guideline value for drinking water. Sawyer and McCarty’s, (1967) classification of hardness (see Table 12) gave the following classes of water: soft water, moderately hard water, and hard water. Following this classification, samples from Otafun, Ogga, Agbajogun Amuro, Odo-Ara, Egbe (I), Egbe (II), Ayede Amuro and Egbe III are soft water while samples from Takete, Iluteju (I), Oroke Efo Amuro, Igbaruku, Okere and Egbe IV are moderately hard water, and

samples from Okeagi, Ogbe, Ogbom, Odole Mopa, Ileteju II and Egbe III are hard water. Depending on the pH and alkalinity, water hardness above 200mg/l can result in scale deposition, particularly on heating. Soft water with hardness of less than about 100mg/l, such as from Otafun, Takete, Ileteju I, Agbajogun Amuro, Odo-Ara, Egbe I, Ayede Amuro and Egbe III have low buffering capacity and may be corrosive to water pipes and borehole risers (WHO, 2006). The chemical parameters calcium ion, Ca 2+ and magnesium Mg 2+ concentration range from 12.0mg/l to70.4mg/l and 0.97mg/l and 20.02mg/l repectively. The concentrations of these parameters in all the groundwater samples are below WHO, (1993) acceptable limit for drinking water. Sodium ion concentration in the groundwater samples range between 17.095mg/l and 56.089mg/l. Nineteen of the twenty samples have their sodium ion concentrations above the WHO, (1993) acceptable limit of 20mg/l. Only sample taken from Odo-Ara with concentration of 17.095mg/l has value below this limit. Potassium ion in the samples range from 9.095mg/l to 28.739mg/l. Water sample taken from Odo-Ara has potassium ion concentration that is below the acceptable limit of 10mg/l. All the groundwater samples except that from Odo-Ara have potassium ion concentrations above the acceptable limit. All iron concentrations are within WHO, (1993) acceptable limit of 0.3mg/l for drinking water except groundwater at Otafun with concentration of 0.57mg/l. Chloride and sulphate ions concentrations in all the groundwater samples are below the WHO, (1993) acceptable limits for drinking water. Nitrate concentration in the groundwater varies. Water samples from Agbajogun Amuro, Oroke Efo Amuro, Odo-Ara, Okere, Egbe III and Ileteju III have concentrations below the WHO, (1993) acceptable limit while the rest fourteen samples have concentrations above the acceptable limit. Five

TABLE 12 Hardness Classification of Water according to Sawyer and McCarty (1967) Hardness mg/l Water Class

(as CaCO 3 ) 0-75 Soft 75-100 Moderately hard 100-300 Hard >300 Very hard Adapted from Todd, 1980

(samples taken from Otafun, Takete, Ogga, Okeagi and Ogbom) out of the fourteen samples have concentrations above the maximum permissible limit which render these five water sources unfit for drinking purposes. Sources of this high nitrate in groundwater could be from sewage disposal, pit latrines, open dumps and from animal dungs. Short-term exposure and high nitrate intake leads to methaemoglobineamia in bottle- fed infants. Methaemoglobineamia is a syndrome in which nitrate is reduced to nitrite in the stomach of infants. The nitrite oxidizes haemogblobin (Hb) to methaemogblobin (Met Hb), which is unable to transport oxygen around the body. At low concentrations, methaemoglobinaemia produces symptoms of lethargy and cyanosis, and at higher concentrations, asphyxia and death (McDonald et al., 2005 ).

Heavy metals are elements of more health concern than other elements in water because they are not biodegradable as such the spatial distributions of these heavy metals are presented in figures. Arsenic: The concentration of this ion varied from 0.004mg/l to 0.01mg/l in the water samples tested. WHO’s (1993) guideline value for arsenic is 0.01mg/l. From the results therefore no water sample has concentration value above the guideline value. Figure 20 is the spatial distribution map of arsenic; it shows areas of equal arsenic concentrations and places of low and high concentrations of the metal. Arsenic in the study area might have been introduced into drinking water sources primarily through the dissolution of naturally occurring minerals and ores since there is no industrial activity going on in the area. Excessive high concentration of arsenic in drinking water is usually related to the development of cancer at several sites, particularly skin, bladder and lungs especially the trivalent inorganic species (WHO, 2006; McDonald et al., 2005 ). Cadmium: Groundwater samples taken from Otafun, Takete, Ogga, Ileteju, Oroke Efo Amuro, Okeagi, Odo-Ara, Ogbe, Egbe I, Ayede Amuro, Okere and Ileteju have thier cadmium concentration values above the WHO, (1993) guideline value of 0.003mg/l for drinking water while the remaining groundwater samples taken from Agbajogun Amuro, Igbaruku, Ogbom, Egbe II, Odole Mopa, Egbe III, Ileteju and Egbe IV have concentrations that are below the guideline value. Possible sources of cadmium contamination in the areas listed above could be domestic wastewater, fertilizer usage and some metal fittings of boreholes.

Figure 20: Spatial Distribution of Arsenic in the Study Area.

Cadmium intake has not been proved to be carcinogenic or genotoxity though it is found to accumulate primarily in the kidneys (WHO, 2006). Reduction of high cadmium concentration in water can be achieved through treatment by coagulation or precipitation softening (WHO, 2006). The spatial distribution of this metal in the study area shows highest concentration around Okeagi and lowest concentration in the east, southeastern, central and

western sections of the study area (Figure 21). Chromium: Results of the water analysis reveal that eleven samples (samples from Otafun, Takete, Ogga, Oroke Efo Amuro, Okeagi, Odo-Ara, Ogbe, Egbe I, Ogbom, Okeere, and Ileteju II) have their values above the WHO, (1993) health-based guideline value of 0.05mg/l. The source of this metal in groundwater of the study area is thought to be from metal fittings in wells (used as well’s wall) and boreholes. Reduction of chromium concentration to as low as 0.015mg/l can be achieved by coagulation techniques (WHO, 2006). Figure 22 shows the spatial distribution of the metal in the study area, with highest concentration around Okeagi and a small part of Egbe, and lowest concentration in the southeast and northwest areas. Lead : The concentration of lead in the groundwater samples tested range between 0.00mg/l and 0.022mg/l. Four of the water samples (samples from Otafun, Okeagi, Ogbe and Egbe I) have concentrations that are above the WHO, (1993) guideline value of for drinking water 0.01mg/l. Drinking water constitutes the major or greater proportion of total intake of lead. Its presence in the water samples analyzed is assumed to be primarily metal fittings in wells and boreholes containing lead as pipes. Lead is a general toxicant that accumulates in the skeleton. Infants, children up to six years of age and pregnant women are the most susceptible to its adverse health effects. Because lead contamination is basically not a raw water contaminant, no treatment is applicable (WHO, 2006). The spatial distribution of this metal in the study area shows highest concentration around Okeagi and Egbe and lowest concentration in the east, southeastern, central and western sections of the study area (Figure 23). Manganese: The water analysis results show that the concentration of this metal in the groundwater samples range between 0.0011mg/l and 0.10mg/l. No water sample analyzed has concentration above the WHO, (1993) health-based guideline value of 0.5mg/l. Through oxidation and filtration treatment techniques, a concentration of about 0.05mg/l can be achieved (WHO, 2006). According to Hem (1985) manganese is naturally occurring in

Figure 21: Spatial Distribution of Cadmium in the Study Area.

Figure 22: Spatial Distribution of Chromium in the Study Area.

Figure 23: Spatial Distribution of Lead in Study Area

many groundwater sources, particularly in anaerobic or low-oxidation conditions. Figure 24 shows the spatial distribution of the metal in the study area, with highest concentration around Ayede and lowest concentration at Okeagi, Otafun and Okeere. Based on Richards (1954) classification of water for irrigation purposes, groundwater samples from Otafun, Takete, Ogga, Ileteju I, Oroke Efo, Amuro, Okeagi, Igbaruku, Ogbe, Ogbom, Odole Mopa, Okere, Ileteju II, Ileteju III and Egbe IV which have electrical conductivity values in the range of 280.1 µscm −1 and 579.2 µscm −1 (see Table 9) fall within “medium salinity hazard” water class. Groundwater samples from Agbajogun Amuro, Odo- Ara, Egbe I, Egbe II Ayede Amuro and Egbe III whose electrical conductivity values range

from 90.1 µscm −1 to 241.2 µscm −1 fall within the “low salinity hazard” water class. Low salinity water can be used for irrigation on most crops in most soils with little likelihood that soil salinity will develop while medium salinity water can be used if a moderate amount of leaching occurs. The sodium adsorption ratio (SAR) of all the groundwater samples tested range between 0.85 and 2.02 (Table 10). Comparing these values with the Richard (1954) classification of irrigation water, the groundwater samples are of the “low sodium hazard” class. Low sodium water can be used for irrigation on almost all soils with little danger of developing harmful levels of sodium. The Wilcox model (Table 13) used a combination of electrical conductivity (EC) and sodium adsorption ratio to classify irrigation water. Two classes of groundwater were identified: excellent/good water and permissible water. Using this classification, samples from Agbajogun Amuro, Odo-Ara, Egbe I, Egbe II, Ayede Amuro and Egbe III are excellent/good water while samples from Otafun, Takete, Ogbe, Ileteju, Oroke Efo Amuro, Okeagi, Igbaruku, Ogbe, Ogbom, Odole Mopa, Okeere, Ileteju Mopa II, Ileteju Mopa III, and Egbe IV are permissible water. Based on the above, the groundwater sources in the area can be explored for irrigation purpose. Comparing the concentration of magnesium (see Table 10) in all the groundwater samples with Tables 14, the groundwater sources in the area are all below the magnesium guideline values for all livestock implying that all the groundwater samples are good for livestock farming. Also, no groundwater sample has heavy metal and nitrate (toxic substance) concentration beyond the upper limit for livestock drinking water (Table 15).

Figure 24: Spatial Distribution of Manganese on the Study Area.

Table 13: Modified Richard Quality Classification of Irrigation Water Water Class Electrical Salinity Sodium Conductivity Hazard Adsorption (us/cm) Ratio Excellent/Good <250 Low 0-10 Permissible 250-750 Medium 10-18 Doubtful 750-2000 High 18-26 Unsuitable 2000-3000 Very high 26-30 Adapted from Todd (1980).

Table 14: Suggested Limit for Magnesium Drinking Water for Livestock Livestock Magnesium(mg/l) Concentration (meq/l) Poultry <250 <21 Swine <250 <21 Horses 250 <21 Cows (lacting) 250 <21 Ewes with lambs 250 <21 Beef cattle 400 33 Adult sheep on 500 41 Dry feed Adapted from Australian water Resources Council (1969)

Table 15: Guidelines for levels of toxic substances in Livestock Drinking Water Constituent Upper limit (mg/l) Arsenic 0.2 Cadmium 0.05 Chromium 1.0 Iron Not needed Lead 0.1 Manganese 0.005 Nitrate 100 Adapted from National Academy of Sciences, (1972) 4.9 Sources of Element and the Controlling Processes In this study, Principal Component Analysis and parameter correlations were used to explain the sources and controlling processes of the geochemical elements. The results of the analyses are presented in Tables 16 and 17. The analysis groups related variables (physical, biological and chemical parameters) into principal associations (components) based on their mutual correlation coefficients. These associations may be interpreted in terms of geological and anthropogenic processes. Application of this analysis has proven effective in hydrogeochemical, lithogeochemical and stream sediment reconnaissance survey as shown by a host of workers (Imeokparia, 1984; Elueze and Olade, 1985; Elueze et al., 2007). Table 18 shows the number of principal components, the loading of variables on each

component and percentage of data variance in the dataset. These four components account for 76.864% of the total variance in the dataset. Variables (parameters) with factor loading equal or greater than 0.55 were considered for each component and are written in bold (Table16). Principal Component One : This component has a high factor loading of electrical conductivity (EC), total solid, total hardness, calcium, calcium hardness, magnesium, magnesium hardness, sodium, sulphate, chloride and explains 39.558% of the total variance (Table 16). In this study, Ca 2+ may be released as weathering product of feldspars, amphiboles and pyroxenes. Calcium (Ca 2+ ) is both abundant in the earth’s crust and extremely mobile in subsurface water (Davies and Dewiest, 1966; Elueze et al., 2007). Magnesium may equally be attributed to the weathering of silicate minerals. It may be from

2− clay minerals associated with the basement rocks (Elueze et al., 2007). Sulphate (SO 4 ) source may be attributed to release from silicate and aluminiosilicate minerals through precipitation and evapotransipiration processes. Chloride concentration in the water sources may be attributed to environmental and atmospheric precipitation. Sodium source is attributed to ion exchange processes in local water flow system. Principal component one can be ascribed to different geological and hydro-geological effects. EC has high correlation with all the earth crust elements; showing that they could be the main contributing parameters to the electrical conductivity of the water samples. High correlation among calcium, calcium hardness and total hardess shows that calcium is the main contributing element to calcium hardness and calcium hardness is assumed to be the predominant source of total hardess.

TABLE 16: Principal Component Analyses of Physical, Biological and Major Element Data Set

Principal Component

Parameters 1 2 3 4 pH .418 .181 .764 .089

Temperature -.179 -.555 -.147 .441

Colour -.118 .862 -.200 .171

Turbidity -.262 .941 .088 .002

Total Bacteria .032 -.042 -.016 -.932

Faecal Coliform .009 -.063 .024 -.910

Electrical .957 .128 -.014 .054 conductivity

TDS .111 .073 .491 .426

Total Suspended .223 .718 .143 .009 Solid

Total Solid .949 .245 .011 .053

Total Hardness .948 -.123 .210 -.016

Calcium Hardness .931 -.068 .158 .005

Magnsium .828 -.178 .249 -.042 Hardness

Calcium .941 -.107 .176 -.037

Magnesium .826 -.180 .249 -.044

Iron -.059 .789 -.341 .066

Sodium .887 .049 .225 -.015

Potasium .434 .251 -.022 .094

Sulphate .782 .004 -.019 .127

Chloride .819 -.048 -.444 -.036

Bicarbonate .356 -.279 .643 .063

Nitrate .449 .221 -.729 .262

Phosphate .240 -.004 .525 .639

% Total Variance 39.558 15.860 12.173 9.273

% Cumulative 39.558 55.418 67.591 76.864 variance

TABLE 17: Correlation Matrix

p T Co Tu T. F. E T T T T C M C M F N K S C H N P H e lo rbi ba co C D S S H a g a g e a O l C O O m ur d c li S S H H 4 O3 3 4 p p 1. - - .1 - - .4 .4 .3 .5 .5 .4 .4 .5 .4 - .5 .0 .2 .0 .4 - .5 H 0 .1 .0 70 .0 .0 6 5 5 0 1 9 7 3 7 .1 6 9 5 2 22 .2 3 0 50 97 6 89 5 2 9 4 6 1 2 4 2 7 5 0 6 5 8 8 0 4 2 1 Te - 1. - - - - - .1 ------.- - - .0 m .1 00 .3 .4 .3 .2 .2 3 .1 .2 .1 .1 .1 .1 .1 .4 .1 .1 .0 .0 .1 .0 8 p 5 95 16 1 65 3 9 9 5 6 7 3 5 3 0 4 5 2 3 34 3 6 0 7 7 0 8 4 0 2 0 1 5 3 8 9 0 5 Co - - 1. .7 - - .0 - .4 .0 - - - - - .8 - .2 - - - .2 - lo .0 .3 00 91 .2 .2 1 .0 4 9 .2 .2 .2 .2 .2 0 .1 2 .0 .0 .2 8 .0 ur 9 95 0 3 44 8 5 5 4 6 6 2 9 2 2 0 5 5 8 29 8 7 7 1 7 6 9 1 1 1 1 6 0 2 Tu .1 - .7 1. - - - .1 .6 ------.7 - .0 - - - .0 - rbi 7 .4 91 00 .0 .0 .1 2 7 .0 .3 .2 .3 .3 .3 1 .1 5 .2 .2 .3 4 .0 d 0 16 0 2 69 3 2 3 1 4 9 5 2 5 5 4 5 0 9 60 6 5 6 3 1 4 8 3 8 4 9 6 8 2

T. - - - - 1. .9 - - - - .0 .0 .0 .0 .0 - - - - .1 - - - ba .0 .3 .2 .0 0 58 .0 .1 .0 .0 1 1 1 7 2 .1 .0 .0 .0 0 14 .1 .4 c 6 17 31 26 0 0 8 5 1 4 0 7 2 0 1 0 6 2 1 1 4 9 4 0 9 7 6 8 6 6 4 0 2 7 F. - - - - .9 1. - - - - - .0 - .0 - - - - - .0 - - - co .0 .2 .2 .0 5 00 .0 .1 .0 .0 .0 2 .0 8 .0 .1 .0 .0 .0 9 07 .2 .4 li 8 65 44 69 8 0 3 6 1 3 0 7 5 1 5 4 3 1 0 7 6 3 3 9 9 3 2 9 8 3 2 2 2 0 1 1 4 E .4 - .0 - - - 1. .1 .2 .9 .8 .8 .7 .8 .7 .0 .8 .3 .7 .8 .2 .4 .2 C 6 .2 18 .1 .0 .0 0 9 0 8 6 5 4 8 4 8 4 8 2 0 79 9 6 5 37 33 0 39 0 0 2 6 6 7 9 5 8 9 9 1 5 1 3 1 9 0 T .4 .1 - .1 - - .1 1. .1 .1 .1 .1 .0 .2 .0 - .1 .0 .2 - .2 - .6 D 5 39 .0 22 .1 .1 9 0 0 9 3 9 2 1 2 .1 2 5 4 .0 15 .0 9 S 2 57 8 63 0 0 2 8 1 4 7 3 7 2 2 3 1 5 3 2 7 0 5 0 4 TS .3 - .4 .6 - - .2 .1 1. .3 .1 .2 .0 .2 .0 .3 .3 .3 .2 .0 - .1 .0 S 5 .1 45 73 .0 .0 0 0 0 6 7 6 2 1 2 5 0 3 1 9 .1 2 5 9 90 5 12 2 2 0 4 1 2 4 9 0 1 9 3 2 0 49 6 0 6 0 TS .5 - .0 - - - .9 .1 .3 1. .8 .8 .7 .8 .7 .1 .8 .4 .7 .7 .2 .4 .2 0 .2 94 .0 .0 .0 8 9 6 0 5 6 1 8 1 4 6 1 2 7 40 9 5 4 58 11 1 39 6 8 4 0 3 0 7 0 5 5 0 9 6 8 0 7 8 0 T. .5 - - - .0 - .8 .1 .1 .8 1. .9 .9 .9 .9 - .8 .3 .6 .6 .5 .2 .3 H 1 .1 .2 .3 1 .0 6 3 7 5 0 5 1 3 1 .1 8 0 6 7 03 2 1 6 64 66 44 4 08 6 1 1 3 0 3 4 7 1 8 0 7 9 9 4 4 0 8 Ca .4 - - - .0 .0 .8 .1 .2 .8 .9 1. .7 .9 .7 - .8 .3 .6 .7 .4 .2 .3 H 9 .1 .2 .2 1 27 5 9 6 6 5 0 4 6 4 .1 3 3 8 5 03 7 5 1 70 69 98 0 7 4 2 0 3 0 7 3 2 6 1 3 6 6 3 7 0 6 M .4 - - - .0 - .7 .0 .0 .7 .9 .7 1. .7 1. - .8 .2 .5 .4 .5 .1 .2 g 7 .1 .2 .3 1 .5 4 2 2 1 1 4 0 6 0 .1 1 2 4 7 63 2 1 H 2 32 21 53 7 3 9 7 4 7 4 7 0 3 0 9 4 6 6 5 5 1 0 0 Ca .5 - - - .0 .0 .8 .2 .2 .8 .9 .9 .7 1. .7 - .8 .2 .6 .7 .4 .2 .3 3 .1 .2 .3 7 81 8 1 1 8 3 6 6 0 6 .2 4 9 9 5 38 8 2 4 50 91 28 2 5 3 9 0 7 3 3 0 1 3 6 6 7 6 7 8 0 7 M .4 - - - .0 - .7 .0 .0 .7 .9 .7 1. .7 1. - .8 .2 .5 .4 .5 .1 .2 g 7 .1 .2 .3 2 .0 4 2 2 1 1 4 0 6 0 .1 1 2 4 7 64 2 0 2 31 21 54 0 52 8 7 0 5 1 2 0 1 0 9 3 4 4 3 5 8 0 2 Fe - - .8 .7 - - .0 - .3 .1 - - - - - 1. - - - .1 - .3 .- .1 .4 02 15 .1 .1 8 .1 5 4 .1 .1 .1 .2 .1 0 .1 .0 .0 1 .3 4 1 7 05 1 42 9 2 1 5 8 6 9 3 9 0 4 4 6 1 50 2 2 2 6 5 8 6 0 7 2 3 2 7 2

Na .5 - - - - - .8 .1 .3 .8 .8 .8 .8 .8 .8 - 1. .4 .5 .5 .4 .1 .2 6 .1 .1 .1 .0 .0 4 2 0 6 8 3 1 4 1 .1 00 90 97 69 04 91 07 5 4 0 4 0 3 9 2 9 0 0 1 4 6 3 4 0 3 1 9 6 2 3 K .0 - .2 .0 - - .3 .0 .3 .4 .3 .3 .2 .2 .2 - .4 1. .5 .2 .1 .2 .2 9 .1 2 5 .0 .0 8 5 3 1 7 3 2 9 2 .0 90 00 30 26 11 69 05 0 5 5 5 6 1 1 3 3 9 0 3 6 6 4 4 0 8 4 0 2 S .2 - - - - - .7 .2 .2 .7 .6 .6 .5 .6 .5 - .5 .5 1. .6 .3 .3 .3 O4 5 .0 .0 .2 .0 .0 2 4 1 2 6 8 4 9 4 .0 97 30 00 57 83 94 00 6 2 5 0 2 0 5 1 2 6 9 6 6 7 4 6 0 9 6 6 0 1 7 Cl .0 - - - .1 .0 .8 - .0 .7 .6 .7 .4 .7 .4 .1 .5 .2 .6 1. .0 .6 .0 2 .0 .0 .2 0 9 0 .0 9 7 7 5 7 5 7 1 69 26 57 00 11 47 01 5 3 8 9 1 7 1 5 0 8 9 6 5 6 3 1 0 0 0 8 0

H .4 - - - - - .2 .2 - .2 .5 .4 .5 .4 .5 - .4 .1 .3 .0 1. - .4 C 2 .1 .2 .3 .1 .0 7 1 .1 4 0 0 6 3 6 .3 04 11 83 11 00 .4 03 O3 2 3 2 6 4 7 9 5 4 0 3 3 3 8 4 5 0 34 4 9 0 1 6 9 0 N - - .2 .0 - - .4 - .1 .4 .2 .2 .1 .2 .1 .3 .1 .2 .3 .6 - 1. - O3 .2 .0 8 4 .1 .2 9 .0 2 9 2 7 2 8 2 4 91 69 94 47 .4 00 .0 8 3 8 6 4 3 3 3 6 0 4 3 5 7 5 2 34 0 34 1 5 2 1 4 P .5 .0 - - - - .2 .6 .0 .2 .3 .3 .2 .3 .2 - .2 .2 .3 .0 .4 - 1. O4 3 8 .0 .0 .4 .4 6 9 5 5 1 5 1 2 0 .1 07 05 00 01 03 .0 00 8 6 7 5 9 3 1 2 0 7 4 7 1 8 8 2 34 0 2 2 7 4 2

Principal Component Two explains 15.86% of total variance which includes temperature, colour, turbidity, total suspended solid and iron. Iron may be associated with the weathering of ferromagnesian minerals. High temperature encouraged weathering of rocks. Iron concentration in the water sources might have been the one of the contributing chemical parameters to the water turbidity, total suspended and colour because members of this second principal component have strong correlation one with another. This principal component reflects the signature of contamination via weathering processes. Principal Component Three explains 12.173% of the total variance and includes pH, bicarbonate and nitrate. The source of bicarbonate in the groundwater samples may be from precipitation and weathering effects. Surface water charged with atmospheric and biogenic

2− CO 3 infiltrates into the subsurface and aggressively attacks alumino-silicates including feldspars and micas present in the basement rocks librating cations such as Ca 2+ and Mg 2+ into the water and leaving residues of clay minerals. A consequence of this incongruent

− dissolution is a rise in pH and HCO 3 concentration of the water (Olobaniyi and Owoyemi,

− 2006; Freeze and Cherry, 1979). Nitrate (NO 3 ) source could be associated with effect of drainage water from agriculture practices, and sewage disposal (animal and human) into streams that drain the area. Principal Component Four : this factor accounts for 9.273% of the total variance and includes faecal coliform, total bacteria and phosphate. Faecal coliform and total bacteria concentration in water is an indication of bacterial growth in water, bacteria occurrence and growth in groundwater is a function of settlement population size and human activities and practices, vadose zone thickness and water retention time (MacDonald et al., 2005). Phosphate is assumed to be from plants remains and uptake.

4.10 Hydro-Geochemical Facies Hydro-geochemical parameters (dominant ions) measured in percentage meliequivalent per litre (% meq/l) positions were plotted on a piper trilinear diagram (Piper, 1944; Figure 25). Based on Furtak and Langgurth (1967) classification, four hydro-geochemical facies were identified. They are sodium-potassium bicarbonate water {Na-(K)- HCO 3 }, calcium – magnesium sulphate waters {Ca-(Mg)- SO 4 }; both of which are earth alkali waters, Calcium- magnesium-sulphate bicarbonate waters {Ca-Mg-( SO 4 )- HCO 3 } and

K E YS *= A •=K *= B •=L •=M * *= C * *= D •=N * •=O * • *= E •• •=P • • *= F =Q • • *= G • • •=R • *= H *• *= I •=S * * •= J =T • • *

N a + S K 3 O o C * 4 + 3 O C g H M

• • •*• • • * * * • • • • *• ** * *• * •• * •** • * * • * * • *• • • Ca Cl Figure 25: Piper Trilinear Diagram

sodium-potassium-sulphate- chloride waters {Na-K-( SO 4 )-Cl} both of which belong to the alkaline waters.

Na-(K)- HCO 3 As shown in Figure 26, this water type is found at Agbajogun, Efo, Ogbe, Okeere, Ileteju Mopa, and Egbe and constitutes 35% of water types in the study area. It is usually

called exchange water due to its evolution through cation exchange process (Loehert, 1970 and 1973). The presence of appreciable amount of clay materials (as cation exchanger) in the weathered overburden unit, and apparently low velocity with resultant relatively longer contact or residence time promoted the active cation exchange reaction as represented below (Elueze et al., 2007 ).

2+ 1/2 Ca - HCO 3 + Na-X → 1/2Ca- X 2 + Na ± HCO 3 (2) [X= clay minerals as cation exchangers] This water type has been reported in some parts of the Basement Complex of Southwestern Nigeria (Tijani, 1994; Tijani and Abimbola, 2003).

Ca-(Mg)- SO 4 This water type is within the normal alkaline water and is encountered at Ogga, Okeagi, Ogbom and Odole (Figure 26). It constitutes 20% of the water studied, and is typical of the Nigerian Basement Complex terrain, with limited mixing (Amadi, 1987). Sulphate is a major constituent of atmospheric precipitation (Davies and Dewiest, 1966) and hence this water type is influenced by precipitation as well as dissolution of silicate minerals in the bedrock and aluminous silicates in the weathered regolith (Tijani, 1994).

Ca-Mg-( SO 4 )- HCO 3 This water type is observed in Iluteju Mopa, Odo Ara, Igbaruku and Egbe, and constitutes 20% of the water type in the study area (Figure 26). It falls within normal alkaline water and is predominantly hydrogen carbonate. It is characterized with high groundwater hardness.

Na-K-( SO 4 )-Cl This facies is found in Otafun, Takete Isao, Egbe and Ayede Amuro (Figure 26) and constitutes 25% of the water types in the area. Sodium sulphate solubility is strongly influenced by temperature. The solid precipitated may contain various amounts of water,

Figure 26: Geochemical Facies Model

ranging from mirabilite or Glauber’s salt with the formular Na 2 SO 4 10. H 2O , through the heptahydate with seven molecules of water and the anhydrous form (Hem, 1985).

4.11 Stiff Pattern The stiff pattern is a graphical representation of water analyses data which shows water-composition differences and similarities (Stiff, 1951). The width of each water sample polygonal shape is an approximate indication of total ionic content (Hem, 1985).

The stiff plot (Figure 27) shows that the groundwater sources in the area have similar total ionic content; this is revealed by the similarity in the widths of each water sample plot but different water-compositions as indicated in the different shapes of each water sample plot.

Figure 27: Stiff Pattern Diagram

CHAPTER FIVE CONCLUSION AND RECOMMENDATIONS Hydro-geological, geophysical and hydro-geochemical investigations were carried out with the objective of characterizing the groundwater potentials of basement complex areas of Mopa/Amuro and Egbe areas of Kogi State. Static water levels measured were used to generate the hydraulic head model of the area. The groundwater flow directions reveal a converging zone and three diverging zones. The converging zone coincides with the basement “lows” or depressions and the middle and lower courses of the surface water drainage system of the area. The zone is classed as probable zone of high groundwater potential because the subsurface water flows into this zone and the groundwater recharge is high at this zone too. The radiating zones on the other hand are zones of probable low groundwater potential. Borehole yields measured from converging zone are higher than those measured from divergence zones though with some exemptions due to variation in basement relief, local and discontinuous nature of the

basement aquifers. Geo-electrical survey results show that the area is characterized with 2-layer to 5-layer subsurface sequences. The 3-layer type constitutes the main layer type and is observed at all locations (towns and villages). The subsurface layers include topsoil, weathered layer, weathered/fractured layer and the fresh bedrock. Four aquifer types that were identified are the weathered layer, weathered/fractured (unconfined), weathered/fractured (confined), and weathered (unconfined) and weathered/fractured (confined). The weathered layer aquifer constitutes the predominant aquifer type, weathered/fractured (confined), and weathered (unconfined) and weathered/fractured (confined) are observed only at Ogga. Areas of thick overburden units and low resistivity values constitute zones of high longitudinal conductance; this parameter was used as a criterion for the aquifer protective capacity rating. The three distinct zones defined are weak, poor and moderate aquifer protective capacity zones. The poor and weak zones are zones which are vulnerable to surface contaminant sources. Three groundwater potential zones were delineated in the study area; the classification criteria used were weathered layer resistivity and thickness, overburden thickness, bedrock

resistivity and borehole yield. Because of the variability in the basement relief and the local and discontinuous nature of the basement aquifers, the three zones vary from place to place. Areas of high aquifer protective capacity coincide with areas of poor groundwater potential; the former increases as the clay content of the overburden increases while the latter decreases with increase in the over burden’s clay content. Results of hydrochemical analyses reveal that the groundwater of the study area is not very potable and suitable for drinking purposes. The entire representative samples analyzed have one or more elements of health concern (nitrate, heavy metals and faecal colifom and total bacteria) whose concentration(s) are above the WHO, 1993 acceptable limits. Some measures of treatments will be needed before their usage as drinking water. The water quality for agricultural purposes such as irrigation, livestock and poultry farming is satisfactory as the water SAR, EC, magnesium and toxic trace metal concentrations are within the acceptable limits. Principal component analysis carried out on the measured parameters to aid in the determination of sources and controlling processes of some of the elements occurring in

water showed that calcium, sodium, magnesium, chloride, sulphate, constitute the elements of first principal component and are associated with weathering of silicates and aluminosilicate minerals. These elements are earth crust elements. The second principal component only occurring element iron is assumed to be released from the weathering of ferromagnesian minerals. Bicarbonate and nitrate make up the elemental ions of the third principal components. Bicarbonate is thought to be from acid rain effect in weathering of silicate rich rocks. This is supported by the high correlation between this ion and pH. Nitrate is believed to come from human/anthropogenic sources such as pit latrines, drainage, animal and domestic dung and agricultural activities. The fourth principal component which includes total bacterial and faecal coliform and phosphate reflects microbial contamination.

RECOMMENDATIONS Based on the work done, the following recommendations are made: • Groundwater development and abstraction should be concentrated in areas of the groundwater convergence (collecting zones).

• Combined geophysical techniques(i.e. electrical resistivity sounding and electromagnetic survey methods) should be used for groundwater explorations in the terrain for better identification of weathered/fractured zones • Groundwater management principles should be encouraged and practiced • Petrol filling stations should be carefully sited especially in areas of weak and poor aquifer protective capacity. The construction of underground petroleum tanks must follow geotechnical engineering designs. • Indiscriminate use of fertilizer for agricultural purposes in areas of poor and weak aquifer protective capacity should be discouraged. • Treatment of water from the study area should be encouraged for domestic uses.

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APPENDICES

APPENDIX I Static Water Level and Hydraulic Head SWL Hydraulic Well Elevation(m) Latitude Longitude (m) head(m) Depth(m) 3.4 278.5 3.5 282 N08 07 47.8 E005 53 50.2 5.2 292.8 5.6 298 N08 06 E005 53 54.2 32.1 3.7 300.3 4.1 304 N08 06 43 E005 53 41.9 4.3 296.7 4.4 301 N08 06 42.6 E005 53 42.8 3.5 304.5 4.0 308 N08 06 41.6 E005 53 43.0 5.3 300.7 5.5 306 N08 06 41.8 E005 53 44.1 3.9 294.1 4.1 298 N08 06 40.6 E005 53 43.7 7.3 297.7 7.6 305 N08 06 40.4 E005 53 44.5 5.7 304.3 5.8 310 N08 06 40.8 E005 53 44.9 3.3 305.7 3.6 309 N08 06 41.2 E005 53 44.8 4.8 296.2 5.1 301 N08 06 40.0 E005 53 43.3 2.9 287.1 3.6 290 N08 06 24.2 E005 53 30.7 3.5 291.5 3.8 295 N08 06 22.9 E005 53 31.2 3.1 301.9 3.75 305 N08 06 21.1 E005 53 39.2

4.4 300.6 4.55 305 N08 06 19.7 E005 53 39.2 5.45 303.55 5.65 309 N08 05 47.8 E005 53 33.8 5.6 312.4 6.7 318 N08 05 47.8 E005 53 40.9 7.1 304.9 7.6 312 N08 05 36.6 E005 53 46.7 6.8 305.2 7.0 312 N08 05 35.6 E005 53 43.0 5.8 305.2 6.0 311 N08 05 36.5 E005 53 41.7 5.65 291.35 5.85 297 N08 09 52.6 E005 53 34.3 3.8 290.2 5.1 294 N08 09 54.1 E005 53 39.1 3.35 271.65 5.75 275 N08 09 52.3 E005 53 39.0 5.9 285.1 6.0 291 N08 09 51.2 E005 53 34.1

5.5 288.5 7.25 294 N08 09 43.1 E005 53 33.5 6.75 283.25 7.5 290 N08 09 41.9 E005 53 36.5 5.0 286 5.8 291 N08 09 43.8 E005 53 38.4 5.3 284.7 5.45 290 N08 09 42.9 E005 53 40.2 0 280 4.45 280 N08 09 39.5 E005 53 54.9 7.1 277.8 7.2 285 N08 09 39.8 E005 53 33.1 5.6 278.4 7.1 284 N08 09 30.3 E005 53 48.7 5.35 277.65 5.4 283 N08 09 29.8 E005 53 47.0 6.0 276 6.1 282 N08 09 30.8 E005 53 47.0 3.8 275.2 4.75 279 N08 09 29.2 E005 53 46.2 0 284 4.0 284 N08 09 24.9 E005 53 49.5 5.2 275.8 5.3 281 N08 09 25.3 E005 53 49.1 7.0 276 7.1 283 N08 09 25.6 E005 53 49.4

4.65 263.35 5.75 268 N08 08 55.7 E005 53 42.7 4.8 281.2 4.92 286 N08 08 41.1 E005 53 52.9 4.25 284.75 4. 6 289 N08 08 40.9 E005 53 52.0 2.1 283.9 2.2 286 N08 08 42.2 E005 53 55.5 7.75 277.25 8.1 285 N08 08 34.4 E005 53 46.2 5.75 275.25 5.90 281 N08 08 36.7 E005 53 45.2 5.0 276 6.0 281 N08 08 26.8 E005 53 45.6 2.99 379.0 3.34 382 N08 07 58.2 E006 04 50.4 5.45 361.55 6.55 367 N08 12 41.9 E005 30 56.5 5.7 345.3 5.85 351 N08 12 37.3 E005 30 46.6 4.9 345.1 5.0 350 N08 12 38.5 E005 30 45.7 5.3 356.7 5.4 362 N08 12 37.7 E005 30 43.5 2.85 335.15 3.85 338 N08 12 35.2 E005 30 40.9 5.45 333.55 5.55 339 N08 12 36.2 E005 30 39.6 5.3 317.7 5.97 323 N08 12 36.2 E005 30 38.4 5.1 334.9 5.4 340 N08 12 43.6 E005 3037.1

4.45 354.55 5.6 359 N08 12 48.8 E005 30 43.4 7.1 349.9 8.1 357 N08 12 51.3 E005 30 38.6 5.6 354.4 5.75 360 N08 12 50.1 E005 30 39.0 5.6 359.4 5.7 365 N08 13 36.1 E005 30 48.6 5.3 358.7 5.4 364 N08 13 36.7 E005 30 48.9 5.9 351.9 6.1 358 N08 13 37.3 E005 30 51.5

6.65 358.35 6.85 365 N08 13 E005 30 50.5 38.8

9.5 335.5 10.2 345 N08 13 42.3 E005 30 22.0 9.4 341.6 10.5 351 N08 13 41.5 E005 3 0 23.1 8.4 343.6 8.8 352 N08 13 39.9 E005 30 25.0 5.95 348.05 6.65 354 N08 13 28.7 E005 30 35.3 5.55 344.55 6.45 350 N08 12 13.2 E005 34 10.6 8.10 340.9 8.25 349 N08 12 14.4 E005 33 54.1 8.5 360.5 9.25 369 N08 12 34.3 E005 31 15.3 7.3 286.7 9.2 294 N08 09 091 E005 48 24.4 10.15 279.85 10.35 290 N08 09 006 E005 48 17.5 6.85 318.15 7.0 325 N08 09 24.4 E005 40 38 4.1 323.9 4.5 328 N08 09 20.0 E005 40.0 37.8 5,8 321.2 6.5 327 N08 09 17.6 E005 40 38.5 6.3 243.7 6.7 250 N08 10 36.5 E005 39 10.2 4.5 274.5 5.05 279 N08 10 33.4 E005 39 11.9 4.8 276.2 5.15 281 N08 10 35.9 E005 39 13.5 4.65 266.35 5.2 271 N08 10 35.9 E005 39 14.1 4.15 277.85 4.2 282 N08 10 32.8 E005 39 08.2 6.25 270.75 8.45 277 N08 14 24.9 E005 36 38.0 0 264 4.55 264 N08 14 16.3 E005 37 0.21 6.7 320.3 6.8 327 N08 15 03.0 E005 35 14.4 0 (DRY 333 3.85 333 N08 15 05.4 E005 35 WELL) 10.2

8.45 388.55 8.62 397 N08 05 02.8 E005 36 53.8 4.1 398.9 4.25 403 N08 05 13.9 E005 36 38.9

6.49 387.51 6.60 394 N08 05 19.0 E005 36 38.0 0 0 6.72 292 N08 09 47.3 E005 56 25.8 6.02 288.98 6.15 295 N08 09 43.5 E005 58 08.5 6.22 285.78 6.35 292 N08 09 42.2 E005 58 10.8 6.15 291.85 6.26 298 N08 09 42.5 E005 58 07.3 7.5 294.5 7.65 302 N08 09 44.5 E005 57 49.3 4.62 342.38 4.85 347 N08 05 39.2 E005 50 00.8 5.3 333.7 5.5 339 N08 05 40.9 E005 49 59.5 5,59 341.41 6.20 347 N08 05 43.8 E005 49 57.7 6.0 337 6.1 343 N08 05 43.5 E005 49 56 .8 6.41 338.59 6.45 345 N08 05 42.2 E005 49 57.1 7.2 345.8 7.55 353 N08 05 42.4 E005 49 56.4 7.8 337.2 7.85 345 N08 05 35.2 E005 49 56.7 7.15 323.85 7.45 331 N08 05 34.3 E005 49 57.2 6.95 339.05 7.05 346 N08 05 34.7 E005 49 55.5 5.8 336.2 5.9 342 N08 05 40.6 E005 49 54.8

5.40 300.6 5.54 306 N08 05 52.6 E005 53 33.8 3.7 334.3 3.85 338 N08 05 42.7 E005 49 50.5 7.1 337.9 7.24 345 N08 05 38.2 E005 49 58.2

Appendix II Summary of Vertical Electrical Sounding Location Curve Types

ρ1 (Ωm) ρ 2 (Ωm) ρ3 (Ωm) ρ 4 (Ωm) ρ5 (Ωm) h1 (m) h2 (m) h3 (m) h4 (m) Okeere 389.40 110.96 592.52 0.49 16.32 H Okeere 110.20 37.71 892.93 1.39 13.20 H Okeere 1278.50 67.06 229.10 1.89 2.35 H Okeere 138.81 81.93 826.32 2.41 4.99 H Okeere 537.82 66.44 1047.70 1.41 2.71 H Egbe 76.90 37.08 82.40 47.04 556.92 0.70 0.74 18.38 2.53 HAH Egbe 33.32 88.64 202.22 0.70 5.91 A Egbe 759.95 228.79 744.13 634.79 1.55 5.20 HK Egbe 297.06 445.88 125.90 634.79 1.49 11.77 16.42 A Egbe 1392.12 1741.58 34.27 717.09 0.00 3.0 1.97 A Egbe 77.0 75.6 404.6 9.0 6.0 H Egbe 64.0 44.7 372.4 514.4 2.0 7.0 5.0 HA

Egbe 110 54.9 334.6 506.8 6.0 3.3 6.7 HA Egbe 159 54.02 326.2 10.0 8.0 H Egbe 18.0 40.44 264.6 6.0 7.0 A Egbe 134 52.0 155.6 6.0 5.0 H Egbe 233 82.8 392.1 527.9 5.0 9.0 4.0 HA Egbe 329 226.5 2.0 H Egbe 150 54.4 481.5 3.0 8.0 H Oroke Efo 792.30 79.89 3391.09 1.69 19.32 H Amuro Oroke Efo 366.49 90.01 1094.66 1.62 4.35 H Amuro Oroke Efo 422.16 992.17 116.65 0.62 3.58 15.57 KH Amuro Oroke Efo 954.94 106.93 113.09 1.30 4.63 H Amuro Oroke Efo 58.26 72.76 1712.71 1.10 11.06 H Amuro Orokere 18.0 40.44 264.6 484.3 6.0 5.0 5.0 AK Amuro Orokere 50.0 149.2 326.2 556.8 5.0 9.6 1.4 AA Amuro Orokere 72.0 256.4 340 899.9 7.0 8.0 4.0 AA Amuro Orokere 113 508.2 1948.1 3.0 2.0 A Amuro Orokere 205 56.9 379.2 531.3 5.6 8.0 4.0 HA Amuro Ayede Amuro 22.0 75.0 100 1500 0.4 2.6 5.0 A Ayede Amuro 25.0 60.0 90.0 3500 0.5 0.2 7.5 A Ayede Amuro 80.0 50.0 100 5000 0.5 2.5 4.5 H Ayede Amuro 180 350 220 120 0.4 2.6 2.0 4.0 KQ Ayede Amuro 20.0 35.0 60.0 850 0.5 2.0 4.0 A Agbajogun 126.58 163.77 101.12 480.79 0.54 2.57 10.59 KH Amuro Agbajogun 557.29 73.47 456.38 4.52 8.19 H Amuro Agbajogun 765.28 124.65 4519.02 0.67 18.19 H Amuro

Agbajogun 300.64 32.55 286.32 3.59 9.78 H Amuro Agbajogun 218.50 37.84 510.83 0.48 5.80 H Amuro Ileteju Mopa 198.83 248.38 88.91 289.17 1.06 3. 43 20.71 KH Ileteju Mopa 370.63 44.60 427.07 5.43 8.85 H Ileteju Mopa 316.36 7.35 208.36 3.55 0.91 H Ileteju Mopa 302.25 59.62 597.37 1.51 15.36 H Ileteju Mopa 110.07 18.06 370 1.31 3.43 A Odole Mopa 223.79 44.39 417.19 0.94 5.21 H Odole Mopa 5422.99 647.47 5145.44 25.40 792.54 0.63 0.68 3.51 0.81 KHK Odole Mopa 92.18 33.21 1.20 28.18 H Odole Mopa 541.16 170.07 751.84 1.02 8.85 H Odole Mopa 333.92 38.91 459.67 0.90 7.94 H Otafun 696.56 56.22 403.04 2.82 3.32 H Otafun 599.99 135.70 16,834 0.91 13.73 H Otafun 629.70 103.52 425.34 2.69 37.52 H Otafun 1070.30 108.41 1382.24 1.58 5.63 H Takete 570 125 82.0 720 1.4 3.8 9.6 >18.8 QH Igbaruku 35.0 50.31 314 8.0 4.0 >14.0 A Igbaruku 27.0 46.4 299 8.0 5.0 >13.0 A Igbaruku 35.0 50.31 310.0 9.0 5.0 >16 A Igbaruku 14.0 41.89 283 8.0 3.0 >13 A Igbaruku 233 82.7 446.8 10.0 6.0 >17.0 A Iyamerin 97.0 51.3 272 6.0 2.0 >10 H Iyamerin 296 59.9 258.1 5.0 9.0 >16.0 H Odo-Ara 32.0 13.5 160 2.7 12.3 >15 H Odo-Ara 20.0 5.0 200 0.9 7.65 H Odo -Ara 38.0 19.0 190 1.2 9.3 H Odo-Ara 15.0 9.0 201.0 1.1 6.9 H Odo-Ara 100 53.0 286 1.3 6.7 H Ogbe 170 93.0 1500 1.4 4.2 H Ogbe 112.0 62.0 1750 1.2 6.92 H Ogbe 120 50.0 950 1.1 7.4 H Ogbe 95.0 76.0 800 1.1 5.4 H Ogbe 135 56.0 625 1.3 10.2 H Ogbom 400 27.0 1585 1.0 9.0 H Ogbom 130 120 2500 0.9 5.1 H

Ogbom 380 210 2100 0.9 4.6 H Ogbom 330 90.0 2150 1.2 6.8 H Ogbom 460 95.0 2500 1.5 6.02 H Ogga 8787 317 4013 274 1.1 6.2 2.3 HK Ogga 322 98.0 5092 76.0 0.9 3.0 5.2 H Ogga 705 123 745 71.0 0.6 2.8 41.4 H Ogga 970 780 133 2751 82 0.6 0.2 8.4 15.1 QHK Ogga 1613 333 3002 248 0.9 1.9 7.1 HK Primary Data Source: (LNRBRDA, 2001, 2001a, 2001b, 2001c, 2001d, 200e, 2002& 2005)

Appendix III Top Soil, Weathered and Fractured Layers’ Thicknesses and Resistivities Location Coordinates(lat&long) TW (m) TF (m) TWF (m) ρW (Ωm) ρ F (Ωm) ρWF (Ωm) TTS (m) ρTS (Ωm) TOB (m) Okeere 16.32 110.96 0.49 389.40 16.81 N08 12’ 14.6” E005 33’ 40.2” Okeere 13.20 37.71 1.39 110.20 14.59 N08 12’ 14.4 E005 33 54.1 Okeere 2.35 ? 67.06 229.10 1.89 1278.50 4.24 N08 12 15.1 E005 33 58.7 Okeere 4.99 81.93 2.41 138.81 7.40 N08 12 15.6 E005 34 11.5 Okeere 2.71 66.44 0.70 537.82 4.12 N08 12 14.7 E005 33 21.6 Egbe 2.53 18.38 47.04 82.40 0.70 76.90 22.35 N08 13 00 E005 30 30 Egbe 5.91 88.64 1.55 33.32 6.61 N08 12 28.1 E005 30 40.1 Egbe 5.20 228.79 1.49 759.95 29.68 N08 12 47.9 E005 30 44.7 Egbe 16.42 125.90 3.0 297.06 13.26 N08 12 40.5 E005 31 01.2 Egbe 1.97 34.27 9.0 1741.58 4.97 N08 12 57 E005 30 41.0 Egbe 9 75.6 9.0 77.0 19.0 N08 13 33.2 E005 31 08.4 Egbe 6.0 372.4 2.0 64.0 16.0 N08 13 29.8 E005 31 09.7 Egbe 334.6 6.0 110 18.0 N08 13 37.1 E005 31 01.6 Egbe 8.0 54.02 10.0 159 19.0 N08 13 36.2 E005 30 54.6 Egbe 7.0 40.44 6.0 18.0 15.0 N08 13 35.8 E005 30 53.7 Egbe 5.0 52.0 6.0 134 12.0 N08 13 36.7 E005 30 54.2 Egbe 13.0 392.1 5.0 233 21.0 N08 14 09.3 E005 30 40.2

Egbe ….. ….. 2.0 329 …….. N08 14 10 E005 30 41 Egbe 8.0 54.4 3.0 150 13.0 N08 12 30.5 E005 29 49.8 Oroke Efo 19.32 79.89 1.69 792.30 21.01 N08 09 20.9 Amuro E005 54 00 Oroke Efo 4.35 90.01 1.62 366.49 5.97 N08 09 29.5 Amuro E005 54 03.2 Oroke Efo 15.57 116.65 0.62 422.16 19.77 N08 09 29.4 Amuro E005 53 55.1 Oroke Efo ? 113.09 1.30 954.94 6.70 N08 09 16.7 Amuro E005 53 45.7 Oroke Efo 11.06 72.76 1.10 583.26 12.16 N08 09 10.1 Amuro E005 53 47 Orokere 10.0 264.6 6.0 18.0 20.0 N08 09 14.5 Amuro E005 53 28.2 Orokere 11.0 326.2 5.0 50.0 18.0 N08 09 09.2 Amuro E005 53 24.5 Orokere 12.0 340 7.0 72.0 22.0 N08 09 10.5 Amuro E005 53 20.2 Orokere 2.0 508.2 3.0 113 7.0 N08 09 06 Amuro E005 53 13.5 Orokere 4.0 379.2 5.6 205 20 N08 09 12.5 Amuro E005 53 26 Ayede Amuro 5.0 100 0.4 22.0 8.0 N08 09 43.4 E005 58 10.1 Ayede Amuro 7.5 90.0 0.5 25.0 10.0 N08 09 43.5 E005 58 08 Ayede Amuro 4.5 100 0.5 80.0 7.5 N08 09 43.4 E005 58 08.1 Ayede Amuro 3.5 120 0.4 180 8.5 N08 09 41.6 E005 57 57.4 Ayede Amuro 4.0 60 0.5 20.0 6.5 N08 09 45.1 E005 58 09.5 Agbajogun 10.59 ? 101.12 480.79 0.54 126 .58 13.70 N08 08 35.3 Amuro E005 53 51.3 Agbajogun 8.19 ? 73.47 456.39 4.52 557.29 12.71 N08 08 44.5 Amuro E005 53 54.2

Agbajogun 18.65 124.65 0.67 765.28 19.32 N08 08 40.3 Amuro E005 53 49.5 Agbajogun 9.78 ? 32.55 286.32 3.59 300.64 13.37 N08 08 51.7 Amuro E005 53 45.8 Agbajogun 5.80 37.84 0.48 218.50 6.28 N08 08 18.6 Amuro E005 53 43.9 Ileteju Mopa 20.71 88.91 1.06 198.83 25.20 N08 06 56.5 E005 53 22.6 Ileteju Mopa ? 427.07 5.43 370.63 14.28 N08 06 50.4 E005 53 31.9 Ileteju Mopa 0.91 ? 7.35 208.36 3.56 316.36 4.46 N08 06 40.3 E005 53 18.7 Ileteju Mopa 15.36 59.62 1.51 302.25 16.87 N08 06 37.3 E005 53 14.6 Ileteju Mopa 3.43 ? 18.06 370 1.31 110.07 4.74 N08 06 44.5 E005 53 12.3 Odol e Mopa 5.21 ? 44.39 417.19 0.94 223.79 6.15 N08 05 50.9 E005 53 32.7 Odole Mopa 0.81 25.40 0.68 647.47 5.63 N08 05 35.9 E005 53 29.1 Odole Mopa 28.18 33.21 1.20 92.18 29.38 N08 05 37.1 E005 53 47.8 Odole Mopa 1.02 541.16 9. 87 N08 04 57.6 E005 54 033 Odole Mopa 7.94 ? 38.91 459.67 0.90 333.92 8.84 N08 06 02.9 E005 53 32.9 Otafun 3.32 ? 56.22 403.04 2.82 696.56 6.14 N08 07 58.2 E006 04 50.4 Otafun 13.73 135.70 0.91 599.99 14.64 N08 08 01.5 E006 04 51. Otafun 103.532 2.69 629.70 40.21 N08 08 01.9 E006 04 48 Otafun 5.63 108.41 1.58 1070.30 7.21 N08 07 55.4 E005 05 48.6 Takete 72 1.4 570 30.0 N08 10 02 E006 01 26 Igbaruku 4.0 50.31 8.0 35.0 14.0 N08 15 08.4 E005 35 11.8

Igbaruku 5.0 46.40 8.0 27.0 13.0 N08 15 21.1 E005 35 08 Igbaruku 50.31 9.0 35.0 16.0 N08 15 03.0 E005 15 03 Igbaruku 4.0 41.89 8.0 14.0 13.0 N08 15 05.4 E005 35 10.2 Igbaruku 82.70 10.0 233 18.0 N08 15 12 E005 35 07 Iyamerin 4.0 51.3 6.0 97.0 11.0 N08 15 04 E005 34 52 Iyamerin 10.0 59.9 5.0 296 17.0 N08 15 03.8 E005 34 48 Odo -Ara 12.3 13.5 2.7 32.0 15.0 N08 14 36.2 E005 36 32 Odo -Ara 7.65 5.0 0.9 20.0 8.55 N08 14 24.9 E005 36 12 Odo -Ara 9.3 19.0 1.2 38.0 10.5 N08 14 24.9 E005 36 38.0 Odo -Ara 9.0 1.1 15.0 8.0 N08 14 16.3 E005 37.0 02.1 Odo -Ara 6.7 53.0 1.3 100 8.0 N08 14 20.5 E005 36 16.2 Ogbe 4.2 93 1.4 170 6.0 N08 05 2.8 E005 36 53.8 Ogbe 6.92 62 1.2 112 8.12 N08 05 13 E005 36 38.9 Ogbe 7.4 50 1.1 120 8.5 N08 05 05.0 E005 36 58.2 Ogbe 5.4 76 1.1 95.0 7.0 N08 05 11.0 E005 36 34.2 Ogbe 10.2 56 1.3 135 12.0 N08 05 20 E005 36 45 Ogbom 9.0 27.0 1.0 400 10.0 N08 09 24.4 E005 40 36.2 Ogbom 5.1 120 0.9 130 6.0 N08 09 26.0 E005 40 33.2 Ogbom 4.6 210 0.9 380 5.5 N08 09 17.6 E005 40 38.5

Ogbom 6.8 90 1.2 330 8.0 N08 09 20.5 E005 40 37.8 Ogbom 6.02 95 1.5 460 7.52 N08 09 22.5 E005 40 54.0 Ogga 6.2 2.3 317 247 1.1 8787 9.6 N08 10 36.2 E005 39 08.2 Ogga 3.0 5.2 98.0 76.0 0.9 322 9.1 N08 10 20.6 E005 38 47.3 Ogga 2.8 41.4 123 71.0 0.6 705 44.8 N08 10 22.7 E005 38 18 Ogga 0.2 15.1 780 82 .0 0.6 970 24.3 N08 10 42.5 E005 39 10.2 Ogga 1.9 7.1 333 248 0.9 1613 9.9 N08 10 35.5 E005 39 16.2

V*S = VES Station, TW (m) = thickness of weathered layer TF (m) = thickness of fractured layer

TWF (m) = thickness of weathered/fractured layer ρW (Ωm) = resistiviry of weathered layer ρ F (Ωm) = resistivity of fractured layer ρWF (Ωm) = resistivity of weathered/fractured layer TTS (m) = thickness of top soil ρTS (Ωm) = resistivity of top soil TOB (m) = overburden thickness Elev.(m) = topographic elevation .

APPENDIX IV BASEMENT RELIEF Location Elevation Overburden Basement Coordinates long/lat amsl (m) Thickness (m) Relief Okeere 348 16.81 N08 12’ 14.6” 331.19 E005 33’ 40.2” Okeere 349 14.59 N08 12’ 14.4 334.41 E005 33 54.1 Okeere 348 4.24 N08 12 15.1 343.76 E005 33 58.7

Okeere 349 7.40 N08 12 15.6 341.60 E005 34 11.5 Okeere 327 4.12 N08 12 14.7 322.88 E005 33 21.6 Egbe 352 22.35 N08 13 00 329.65 E005 30 30 Egbe 340 6.61 N08 12 28.1 333.39 E005 30 40.1 Egbe 359 29.68 N08 12 47.9 329.32 E005 30 44.7 Egbe 364 13.26 N08 12 40.5 350.74 E005 31 01.2 Egbe 365 4.97 N08 12 57 E005 30 360.03 41.0 Egbe 370 19.0 N08 13 33.2 531.00 E005 31 08.4 Egbe 376 16.0 N08 13 29.8 360.00 E005 31 09.7 Egbe 18.0 N08 13 37.1 343.00 E005 31 01.6 Egbe 361 19.0 N08 13 36.2 342.00 E005 30 54.6 Egbe 361 15.0 N08 13 35.8 346.00 E005 30 53.7 Egbe 360 12.0 N08 13 36.7 348.00 E005 30 54.2 Egbe 333 21.0 N08 14 09.3 312.00 E005 30 40.2 Egbe 330 …….. N08 14 10 ------E005 30 41 Egbe 352 13.0 339.00 N08 12 30.5 E005 29 49.8 Oroke Efo Amuro 278 21.01 N08 09 20.9 256.99 E005 54 00 Oroke Efo Amuro 280 5.97 N08 09 29.5 274.03 E005 54 03.2 Oroke Efo Amuro 282 19.77 N08 09 29.4 262.23 E005 53 55.1 Oroke Efo Amuro 273 6.70 N08 09 16.7 266.30 E005 53 45.7

Oroke Efo Amuro 266 12.16 N08 09 10.1 253.84 E005 53 47 Orokere Amuro 295 20.0 N08 09 14.5 275.00 E005 53 28.2 Orokere Amuro 296 18.0 N08 09 09.2 278.00 E005 53 24.5 Orokere Amuro 278 22.0 N08 09 10.5 256.00 E005 53 20.2 Orokere Amuro 282 7.0 N08 09 06 275.00 E005 53 13.5 Orokere Amuro 291 20 N08 09 12.5 271.00 E005 53 26 Ayede Amuro 292 8.0 N08 09 43.4 284.00 E005 58 10.1 Ayede Amuro 290 10.0 N08 09 43.5 280.00 E005 58 08.9 Ayede Amuro 291 7.5 N08 09 43.4 283.50 E005 58 08.1 Ayede Amuro 297 8.5 N08 09 41.6 288.50 E005 57 57.4 Ayede Amuro 289 6.5 N08 09 45.1 282.50 E005 58 09.5 Agbajogun Amuro 286 13.70 N08 08 35.3 272.3 E005 53 51.3 Agbajogun Amuro 276 12.71 N08 08 44.5 263.29 E005 53 54.2 Agbajogun Amuro 279 19.32 N08 08 40.3 259.68 E005 53 49.5 Agbajogun Amuro 264 13.37 N08 08 51.7 250.63 E005 53 45.8 Agbajogu n Amuro 278 6.28 N08 08 18.6 271.72 E005 53 43.9 Ileteju Mopa 284 25.20 N08 06 56.5 258.80 E005 53 22.6 Ileteju Mopa 294 14.28 N08 06 50.4 279.72 E005 53 31.9 Ileteju Mopa 290 4.46 N08 06 40.3 285.54 E005 53 18.7

Ileteju Mopa 289 16.87 N08 0 6 37.3 272.13 E005 53 14.6 Ileteju Mopa 288 4.74 N08 06 44.5 283.26 E005 53 12.3 Odole Mopa 310 6.15 N08 05 50.9 303.85 E005 53 32.7 Odole Mopa 307 5.63 N08 05 35.9 301.37 E005 53 29.1 Odole Mopa 320 29.38 N08 05 37.1 290.62 E005 53 47.8 Odole Mopa 302 9.87 N08 04 57.6 292.13 E005 54 033 Odole Mopa 296 8.84 N08 06 02.9 287.16 E005 53 32.9 Otafun 382 6.14 N08 07 58.2 375.86 E006 04 50.4 Otafun 283 14.64 N08 08 01.5 268.36 E006 04 51.7 Otafun 40.21 N08 08 01.9 334.79 E006 04 48 Otafun 376 7.21 N08 07 55.4 368.79 E005 05 48.6 Takete 30.0 N08 10 02 255.00 E006 01 26 Igbaruku 347 14.0 N08 15 08.4 333.00 E005 35 11.8 Igbaruku 340 13.0 N08 15 21.1 327.00 E005 35 08 Igbaruku 16.0 N08 15 03.0 311.00 E005 15 03 Igbaruku 333 13.0 N08 15 05 .4 320.00 E005 35 10.2 Igbaruku 18.0 N08 15 12 310.00 E005 35 07 Iyamerin 324 11.0 N08 15 04 313.00 E005 34 52 Iyamerin 325 17.0 N08 15 03.8 308.00 E005 34 48

Odo -Ara 282 15.0 N08 14 36.2 267.00 E005 36 32 Odo -Ara 278 8.55 N08 14 24.9 269.45 E005 36 12 Odo -Ara 277 10.5 N08 14 24.9 266.50 E005 36 38.0 Odo -Ara 8.0 N08 14 16.3 256.00 E005 37.0 02.1 Odo -Ara 282 8.0 N08 14 20.5 274.00 E005 36 16.2 Ogbe 397 6.0 N08 05 2.8 391.00 E005 36 53.8 Ogbe 403 8.12 N08 05 13 394.88 E005 36 38.9 Ogbe 396 8.5 N08 05 05.0 387.50 E005 36 58.2 Ogbe 405 7.0 N08 05 11.0 398.00 E005 36 34.2 Ogbe 394 12.0 N08 05 20 382.00 E005 36 45 Ogbom 325 10.0 N08 09 24.4 315.00 E005 40 36.2 Ogbom 326 6.0 N08 09 26.0 320.00 E005 40 33.2 Ogbom 330 5.5 N08 09 17.6 324.50 E005 40 38.5 Ogbom 324 8.0 N08 09 20.5 316.00 E005 40 37.8 Ogbom 325 7.52 N08 09 22.5 317.48 E005 40 54.0 Ogga 282 9.6 N08 10 36.2 272.40 E005 39 08.2 Ogga 281 9.1 N08 10 20.6 271.90 E005 38 47.3 Ogga 279 44.8 N08 10 22.7 234.20 E005 38 18 Ogga 281 24.3 N08 10 42.5 256.70 E005 39 10.2

100

Ogga 268 9.9 N08 10 35.5 258.10 E005 39 16.2

APPENDIX V

LONGITUDINAL CONDUCTANCE AND AQUIFER PROTECTIVE CAPACITY Location Longitudinal Aquifer Coordinate Elevation Conductance Protective amsl (m) (mhos) Capacity Rating Okeere Poor N08 12’ 14.6” 348 0.0013 E005 33’ 40.2” Okeere Poor N08 12’ 14.4 349 0.0126 E005 33 54.1 Okeere Poor N08 12 15.1 348 0.0015 E005 33 58.7 Okeere Poor N08 12 15.6 349 0.0174 E005 34 11.5 Okeere Poor N08 12 14.7 327 0.0026 E005 33 21.6 Egbe Poor N08 13 00 352 0.0291 E005 30 30 Egbe Poor N08 12 28.1 340 0.0210 E005 30 40.1 Egbe Poor N08 12 47.9 359 0.0020 E005 30 44.7

101

Egbe Poor N08 12 40.5 364 0.0314 E005 31 01.2 Egbe Poor N08 12 57 E005 30 365 0.0017 41.0 Egbe Weak N08 13 33.2 370 0.116 E005 31 08.4 Egbe Weak N08 13 29.8 376 0.1597 E005 31 09.7 Egbe Poor N08 13 37.1 361 E005 31 01.6 Egbe Poor N08 13 36.2 361 0.0629 E005 30 54.6 Egbe Moderate N08 13 35.8 361 0.333 E005 30 53.7 Egbe Poor N08 13 36.7 360 0.0448 E005 30 54.2 Egbe Poor N08 14 09.3 333 0.02146 E005 30 40.2 Egbe Poor N08 14 10 330 0.0061 E005 30 41 Egbe Poor N08 12 30.5 E005 29 352 0.0200 49.8 Oroke Efo Amuro Poor N08 09 20.9 278 0.0021 E005 54 00 Oroke Efo Amuro Poor N08 09 29.5 280 0.0044 E005 54 03.2 Oroke Efo Amuro Poor N08 09 29.4 282 0.0051 E005 53 55.1 Oroke Efo Amuro Poor N08 09 16.7 273 0.0447 E005 53 45.7 Oroke Efo Amuro Poor N08 09 10.1 266 0.0019 E005 53 47 Orokere Amuro Poor N08 09 14.5 295 0.04569 E005 53 28.2 Orokere Amuro Weak N08 09 09.2 296 0.1643 E005 53 24.5 Orokere Amuro Weak N08 09 10.5 278 0.1284 E005 53 20.2

102

Orokere Amuro Poor N08 09 06 282 0.0265 E005 53 13.5 Orokere Amuro Weak N08 09 12.5 291 0.1679 E005 53 26 Ayede Amuro Poor N08 09 43.4 292 0.0528 E005 58 10.1 Ayede Amuro Poor N08 09 43.5 290 0.0533 E005 58 08.9 Ayede Amuro Poor N08 09 43.4 291 0.0563 E005 58 08.1 Ayede Amuro Poor N08 09 41.6 297 0.0187 E005 57 57.4 Ayede Amuro Poor N08 09 45.1 289 0.0821 E005 58 09.5 Agbajogun Poor N08 0 8 35.3 286 0.0200 Amuro E005 53 51.3 Agbajogun Poor N08 08 44.5 276 0.0081 Amuro E005 53 54.2 Agbajogun Poor N08 08 40.3 279 0.0009 Amuro E005 53 49.5 Agbajogun Moderate N08 08 51.7 264 0.3124 Amuro E005 53 45.8 Agbajogun Poor N08 08 18.6 278 0.0022 Amuro E005 53 43.9 Ileteju Mopa Poor N08 06 56.5 284 0.0191 E005 53 22.6 Ileteju Mopa Moderate N08 06 50.4 294 0.2131 E005 53 31.9 Ileteju Mopa Weak N08 06 40.3 290 0.1350 E005 53 18.7 Ileteju Mopa Poor N08 06 37.3 289 0.0038 E005 53 14.6 Ileteju Mopa Moderate N08 06 44.5 288 0.2018 E005 53 12.3 Odole Mopa Poor N08 05 50.9 310 0.0004 E005 53 32.7 Odole Mopa Poor N08 05 35.9 307 0.0012 E005 53 29.1

103

Odole Mopa Poor N08 05 37.1 320 0.0130 E005 53 47.8 Odole Mopa Poor N08 04 57.6 302 0.0539 E005 54 033 Odole M opa Moderate N08 06 02.9 296 0.2068 E005 53 32.9 Otafun Poor N08 07 58.2 382 0.0040 E006 04 50.4 Otafun Poor N08 08 01.5 283 0.0015 E006 04 51.7 Otafun Poor N08 08 01.9 375 E006 04 48 Otafun Poor N08 07 55.4 376 0.0015 E005 05 48.6 Takete Poor N08 10 02 285 E006 01 26 Igbaruku Moderate N08 15 08.4 347 0.2286 E005 35 11.8 Igbaruku Moderate N08 15 21.1 340 0.2963 E005 35 08 Igbaruku Moderate N08 15 03.0 327 E005 15 03 Igbaruku Moderate N08 15 05.4 333 0.5714 E005 35 10.2 Igbaruku Poor N08 15 12 328 E005 35 07 Iyamerin Poor N08 15 04 324 0.0619 E005 34 52 Iyamerin Poor N08 15 03.8 325 0.0169 E005 34 48 Odo -Ara Poor N08 14 36.2 282 0.0844 E005 36 32 Odo -Ara Poor N08 14 24.9 278 0.0450 E005 36 12 Odo -Ara Poor N08 14 24.9 277 0.0316 E005 36 38.0 Odo -Ara Poor N08 14 16.3 264 E005 37.0 02.1

104

Odo -Ara Poor N08 14 20.5 282 0.0130 E005 36 16.2 Ogbe Poor N08 05 2.8 397 0.0082 E005 36 53.8 Ogbe Poor N08 05 13 403 0.0107 E005 36 38.9 Ogbe Poor N08 05 05.0 396 0.0092 E005 36 58.2 Ogb e Poor N08 05 11.0 405 0.0116 E005 36 34.2 Ogbe Poor N08 05 20 394 0.0096 E005 36 45 Ogbom Poor N08 09 24.4 325 0.0025 E005 40 36.2 Ogbom Poor N08 09 26.0 326 0.0069 E005 40 33.2 Ogbom Poor N08 09 17.6 330 0.0024 E005 40 38.5 Ogbom Poor N08 09 20.5 324 0.0036 E005 40 37.8 Ogbom Poor N08 09 22.5 325 0.0033 E005 40 54.0 Ogga Poor N08 10 36.2 282 0.0001 E005 39 08.2 Ogga Poor N08 10 20.6 281 0.0028 E005 38 47.3 Ogga Poor N08 10 22.7 279 0.0009 E005 38 18 Ogga Poor N08 10 42.5 281 0.0006 E005 39 10.2 Ogga Poor N08 10 35.5 268 0.0006 E005 39 16.2

105

APPENDIX VI

GROUNDWATER POTENTIAL RATING (G.W.P.R.) Location G.W.P.R. Characteristics Curve Remark Types Okeere Medium Overburden thickness= H Nill 16.81m weathered Layer thickness= 16.32m Weathered layer resistivity= 110.96 bedrock resistivity = 592.52 Ωm yield=2.0l/s Okeere Medium Overburden thickness= H Nill 14.59m weathered Layer thickness= 13.20m Weathered layer resistivity= 37.71 bedrock resistivity = 892.93 Ωm Okeere Low Overburden thickness= 4.24m H Nill weathered Layer thickness= 2.35m Weathered layer resistivity= 67.06 Ωm bedrock resistivity = 229.10 Ω Okeere Low Overburden thickness= H Nill 7.40m weathered Layer thickness= 4.99m Weathered layer resistivity= 81.93 bedrock resistivity = 826.32 Okeere Low Overburden thickness= H Nill 4.12m weathered Layer thickness= 2.71m Weathered layer resistivity= 66.44 Ωm bedrock resistivity = 1047.70 Ωm Egbe High Overburden thickness= HAH Nill 22.35m weathered Layer thickness= 20m Weathered layer resistivity= 82.40 Ωm bedrock resistivity = 556.92 Ωm yield= 2.5l/s

106

Egbe Low Overburden thickness= 6.61m A Nill weathered Layer thickness= 5.91m Weathered layer resistivity=88.64 Ωm bedrock resistivity = 202.22 Ωm Egbe Low Overburden thickness= 6.7m HK Nill weathered Layer thickness= 5.91m Weathered layer resistivity= 744.13 Ωm bedrock resistivity = 634.79 Ωm Egbe Medium Overburden thickness= A Nill 19.42m weathered Layer thickness= 16.42m Weathered layer resistivity= 125 Ωm bedrock resistivity = 634.79 Ωm Egbe Low Overburden thickness= 3.0m A Nill weathered Layer thickness= 1.97m Weathered layer resistivity= 34.27 Ωm bedrock resistivity = 717.09 Ωm Egbe Medium Overburden thickness= 15m H Well fractured bedrock weathered Layer thickness= 9.5m Weathered layer resistivity= 75.6 Ωm bedrock resistivity =404.6 Ωm Egbe Low Overburden thickness= HA Nill 16.0m weathered Layer thickness= 6.0m Weathered layer resistivity=372.4 Ωm bedrock resistivity = 514.4 Ωm Egbe Overburden thickness= HA Nill 18.0m weathered Layer thickness= 10.0m Weathered layer resistivity= 334.6 Ωm bedrock resistivity = 506.8 Ωm Egbe Low Overburden thickness= H Low weathered layer 19.0m weathered Layer thickness= 8.0m Weathered layer resistivity= 54.02 Ωm bedrock resistivity = 326.2 Ωm

107

Egbe Low Overburden thickness= A Nill 15.0m weathered Layer thickness= 7.0m Weathered layer resistivity=40.44 Ωm bedrock resistivity = 264.6 Ωm Egbe Low Overburden thickness= H Weathered/fracture (good 12.0m weathered Layer permeability but thin thickness= 5m weathered layer ) Weathered layer resistivity= 52.0 Ωm bedrock resistivity = 1556 Ωm Egbe Medium Overburden thickness= 21.0m HA Nill weathered Layer thickness= 13.0m Weathered layer resistivity= 82.8 Ωm bedrock resistivity =392.1 Ωm Egbe Low Overburden thickness= H No detail result weathered Layer thickness= 2.0m1 Weathered layer resistivity= bedrock resistivity = Egbe Low Overburden thickness= H Good permeability 13.0mm weathered Layer thickness= 8.0m Weathered layer resistivity= 54.4 Ωm bedrock resistivity =481.5 Ωm Oroke Efo Medium Overburden thickness= H Well weathered layer but Amuro 21.0m weathered Layer poor bedrock fracturing thickness= 19.32m Weathered layer resistivity= 79.89 Ωm bedrock resistivity = 3391.09 Ωm yield= 2.0l/s Oroke Efo Low Overburden thickness= 5.97m H Poorly fractured bedrock, Amuro weathered Layer thin weathered thickness=4.35 m Weathered layer resistivity= 90.01 Ωm bedrock resistivity = 1094.66 Ωm Oroke Efo Medium Overburden thickness= KH Low weathering, high Amuro 19.77m weathered Layer fracturing of bedrock thickness= 15.57+3.58m Weathered layer resistivity= 792.17 Ωm bedrock resistivity =110.65 Ωm

108

Oroke Efo Low Overburden thickness= 6.7m H Nill Amuro weathered Layer thickness= 4.63m Weathered layer resistivity= 106.93 Ωm bedrock resistivity = 113.09 Ωm Oroke Efo Medium Overburden thickness= H Nill Amuro 13.16m weathered Layer thickness= 11.06m Weathered layer resistivity= 72.76 Ωm bedrock resistivity = 1712.7 Ωm Orokere Medium Overburden thickness= AK Nill Amuro 20.0m weathered Layer thickness= 10.0m Weathered layer resistivity=40.44 Ωm bedrock resistivity = 484.3 Ωm yield= 2.0l/s Orokere Medium Overburden thickness= 18.0m AA Fractured bedrock Amuro weathered Layer thickness= 11.0m Weathered layer resistivity= 149.2 Ωm bedrock resistivity = 556.8 Ωm Orokere Medium Overburden thickness= 22.0m AA Poor weathered layer, Amuro weathered Layer thickness= some fracturing of the 12.0m bedrock Weathered layer resistivity= 256.4 Ωm bedrock resistivity = 889 Ω Orokere Low Overburden thickness= 7.0m A Poor weathered layer and Amuro weathered Layer thickness= poor fracturing 2.0mm Weathered layer resistivity= 508.2 Ωm bedrock resistivity = 1948.1 Ωm Orokere Low Overburden thickness= 20.0m HA Topsoil more of clay Amuro weathered Layer thickness= 4.0m Weathered layer resistivity= 379.2 Ωm bedrock resistivity = 531.3 Ωm Ayede Low Overburden thickness= 8.0m A Little fractured bedrock Amuro weathered Layer thickness= 5.0m Weathered layer resistivity= 100m bedrock resistivity = 1500 Ωm

109

Ayede Low Overburden thickness= 10m A Negligible fracturing of Amuro weathered Layer thickness= bedrock 5.0m Weathered layer resistivity= 90 Ωm bedrock resistivity = 3500 Ωm Ayede Low Overburden thickness= 7.5m H Negligible fracture of Amuro weathered Layer thickness= bedrock 4.5m Weathered layer resistivity= 100 Ω bedrock resistivity = 5000 Ωm Ayede Low Overburden thickness= 8.5m KQ Nill Amuro weathered Layer thickness= 3.5m Weathered layer resistivity= 220 Ωm bedrock resistivity = 120 Ωm Ayede Low Overburden thickness= 6.5m A Nill Amuro weathered Layer thickness= 4.0m Weathered layer resistivity= 60.0 Ωm bedrock resistivity = 850 Ωm Agbajogun Medium Overburden thickness= KH Nill Amuro 13.70m weathered Layer thickness= 10.59m Weathered layer resistivity= 101.12 Ωm bedrock resistivity = 480.79 Ωm Agbajogun Low Overburden thickness= H Nill Amuro 12.71m weathered Layer thickness= 8.19m Weathered layer resistivity= 73.47 Ωm bedrock resistivity = 456.38 Ωm Agbajogun Low Overburden thickness= H Good weathered layer but Amuro 19.32m weathered Layer poor bedrock fracturing thickness= 18.65m and very low yield Weathered layer resistivity=73.47 Ωm bedrock resistivity = 4519.02 Ωm yield= 0.4l/s Agbajogun Low Overburden thickness= H Nill Amuro 13.37m weathered Layer thickness= 9.78m Weathered layer resistivity= 32.55 Ωm bedrock resistivity = 286.32 Ωm

110

Agbajogun Low Overburden thickness= 6.28m H Nill Amuro weathered Layer thickness= 5.8m Weathered layer resistivity= 37.84 Ωm bedrock resistivity = 510.83 Ωm Ileteju Medium Overburden thickness= KH Nill Mopa 25.20m weathered Layer thickness= 20.71m Weathered layer resistivity= 88.91 Ωm bedrock resistivity = 289.17 Ωm Ileteju Low Overburden thickness= H Nill Mopa 14.28m weathered Layer thickness= 8.85m Weathered layer resistivity= Ω bedrock resistivity = 427.07 Ωm Ileteju Low Overburden thickness= 4.46m H Very much clay at the Mopa weathered Layer thickness= weathered layer 0.91m Weathered layer resistivity= 7.35 Ωm bedrock resistivity = 208.36 Ωm Ileteju Medium Overburden thickness= H Nill Mopa 16.87m weathered Layer thickness= 15.36m Weathered layer resistivity= 59.62 Ωm bedrock resistivity = 597.37 Ωm yield= 2.0l/s Ileteju Low Overburden thickness= 4.74m A Much clay at the Mopa weathered Layer thickness= weathered layer 3.43m Weathered layer resistivity= 18.06 Ωm bedrock resistivity = 370 Ωm Odole Low Overburden thickness= 6.15m H Nill Mopa weathered Layer thickness= 5.21m Weathered layer resistivity= 44.39 Ω bedrock resistivity = 417.19 Ωm Odole Low Overburden thickness= KHK Nill Mopa 5.63m weathered Layer thickness= 10.81m Weathered layer resistivity= 25.40 Ωm bedrock resistivity = 792.54 Ωm

111

Odole Medium Overburden thickness= H Clay rich weathered zone Mopa 29.38m weathered Layer and negligible fracture of thickness= 28.18m bedrock Weathered layer resistivity= 33.21 Ωm bedrock resistivity = ∞Ωm yield= 2.0l/s Odole Low Overburden thickness= H Nill Mopa 9.87m weathered Layer thickness= 8.85m Weathered layer resistivity= 170.07 Ωm bedrock resistivity = 751.84 Ωm Odole Low Overburden thickness= H Nill Mopa 8.84m weathered Layer thickness= 7.94m Weathered layer resistivity=38.0 Ωm bedrock resistivity = 459.67 Ωm Otafun Low Overburden thickness= 6.14m H Nill weathered Layer thickness= 3.32m Weathered layer resistivity= 556.22 Ω bedrock resistivity = 403.04 Ωm Otafun Medium Overburden thickness= H Medium clay content, low 14.64m weathered Layer effect of bedrock fracture thickness= 13.73m Weathered layer resistivity= 135.70 Ωm bedrock resistivity =16,834 Ωm Otafun Overburden thickness= H Nill 40.21m weathered Layer thickness= 37.52m Weathered layer resistivity= 103.52 Ωm bedrock resistivity = 425.34 Ωm yield= 0.2l/s Otafun Low Overburden thickness= 7.21m H Nill weathered Layer thickness= 5.63m Weathered layer resistivity= 108.41 Ωm bedrock resistivity = 1382.24 Ωm Takete Overburden thickness= QH Nill 14.8m weathered Layer thickness= 9.6m Weathered layer resistivity= 82.0 Ωm bedrock resistivity = 720.0 Ωm

112

Igbaruku Low Overburden thickness= 12.0m A Nill weathered Layer thickness= 4.0m Weathered layer resistivity= 50.31 Ωm bedrock resistivity = 314.0 Ωm Igbaruku Low Overburden thickness= A Nill 13.0mm weathered Layer thickness= 5.0m Weathered layer resistivity= 46.4 Ωm bedrock resistivity =299.0 Ωm Igbaruku Overburden thickness= 16.0m A Nill weathered Layer thickness= 5.0m Weathered layer resistivity= 50.31 Ωm bedrock resistivity = 310.0 Ωm Igbaruku Low Overburden thickness= A Nill 13.0m weathered Layer thickness= 4.0m Weathered layer resistivity= 41.89 Ωm bedrock resistivity = 283 Ωm Igbaruku Overburden thickness= 18m A Nill weathered Layer thickness= 6.0m Weathered layer resistivity= 82.7 Ωm bedrock resistivity = 446.8 Ωm Iyamerin Low Overburden thickness= H Nill 11.0m weathered Layer thickness= 10.0m Weathered layer resistivity= 59.9 Ωm bedrock resistivity = 258.1 Ωm Iyamerin Medium Overburden thickness= H Nill 17.0m weathered Layer thickness= 10.0m Weathered layer resistivity= 59.9 Ωm bedrock resistivity = 258.1 Ωm Odo-Ara Low Overburden thickness= H Weathered layer has much 15.0m weathered Layer clay content thickness= 12.3m Weathered layer resistivity= 13.5 Ωm bedrock resistivity = 160 Ωm

113

Odo -Ara Low Overburden thickness= 8.85m H Weathered layer is clay weathered Layer thickness= rich 7.65m Weathered layer resistivity= 5.0 Ωm bedrock resistivity = 200 Ωm Odo-Ara Low Overburden thickness= 10.5m H Weathered layer is clay weathered Layer thickness= rich 9.3m Weathered layer resistivity= 19.0 Ωm bedrock resistivity =190 Ωm Odo-Ara Overburden thickness= 8.0m H Weathered layer is clay weathered Layer thickness= rich 6.9m Weathered layer resistivity= 9.0 Ωm bedrock resistivity = 201 Ωm Odo-Ara Low Overburden thickness= 8.0m H Nill weathered Layer thickness= 6.7m Weathered layer resistivity= 53.0 Ωm bedrock resistivity = 286 Ωm Ogbe Low Overburden thickness= 6.0m H Reduced effect of weathered Layer thickness= fracturing 4.2m Weathered layer resistivity= 93.0 Ωm bedrock resistivity = 1500 Ωm Ogbe Low Overburden thickness= 8.12m H Reduced bedrock weathered Layer thickness= fracturing 6.92m Weathered layer resistivity= 62.0 Ωm bedrock resistivity = 1750 Ωm Ogbe Low Overburden thickness= 8.5m H Nill weathered Layer thickness= 7.4m Weathered layer resistivity= 50.0 Ωm bedrock resistivity = 950 Ωm Ogbe Low Overburden thickness= 7.0m H Nill weathered Layer thickness= 5.4m Weathered layer resistivity= 56.0 Ωm bedrock resistivity = 625 Ωm

114

Ogbe Medium Overburden thickness= 10.2m H Nill weathered Layer thickness= 12.0m Weathered layer resistivity= 56.0 Ωm bedrock resistivity = 625 Ωm Ogbom Low Overburden thickness= 10.0m H Weathered layer clay rich weathered Layer thickness= and reduced fracturing of 9.0m bedrock Weathered layer resistivity= 27.0 Ωm bedrock resistivity = 1585 Ωm Ogbom Low Overburden thickness= 6.0m H Reduced fracturing of weathered Layer thickness= bedrock 5.1m Weathered layer resistivity= 120 Ωm bedrock resistivity = 2500 Ωm Ogbom Low Overburden thickness= 5.5m H Reduced fracturing of weathered Layer thickness= bedrock 4.6m Weathered layer resistivity= 210 Ωm bedrock resistivity = 2100 Ωm Ogbom Low Overburden thickness= 8.0m H Reduced effect of weathered Layer fracturing of bedrock thickness=6.8m Weathered layer is thin Weathered layer resistivity= hence 95 Ωm bedrock resistivity = Yield is low 21500 Ωm yield= 0.2l/s Ogbom Low Overburden thickness= H Reduced fracturing of 7.52m weathered Layer bedrock

thickness= 6.02m

Weathered layer resistivity=

95 Ωm bedrock resistivity =

2500 Ωm Ogga Low Overburden thickness= 9.6m HK Nill weathered Layer thickness= 8.5m Weathered layer resistivity= 317 Ωm bedrock resistivity = ∞Ωm Ogga Low Overburden thickness= 9.1m H Nill weathered Layer thickness= 8.2m Weathered layer resistivity= 98 Ωm bedrock resistivity = 76.0 Ωm

115

Ogga Medium Overburden thickness= H Nill 44.8m weathered Layer thickness= 41.4m Weathered layer resistivity= 71.0 Ω bedrock resistivity = ∞Ωm yield= 2.0l/s Ogga Medium Overburden thickness= 24.3m QHK Nill weathered Layer thickness= 15.7m Weathered layer resistivity= 82 Ωm bedrock resistivity = ∞Ωm Ogga Low Overburden thickness= HK Nill 9.99m weathered Layer thickness= 2.8m Weathered layer resistivity= 248 Ωm bedrock resistivity = ∞Ωm

APPENDIX VII

GEO-ELECTRIC SECTIONS AND AQUIFER TYPES

113 Ωm 508.2 Ωm N VES 4 VES 1 VES 2 VES 3 VES 5 0 − − − − − − − − − − − − − − − − − 5 − − − − −− − − − − −18.0 − −Ω −m − − − − − − 50.0 Ωm − − − − −72.0 − Ωm− − − 205 Ω − − − − − − לל לל − − − − − לל לל לל 10 − − − לל לל לל לל לל Ωm 256.4 Ωm 56.9 Ω 149.2 לל x 40.44 Ωm − − − − לל לל + x x 15 − − − − − לל לל לל לל לל + x לל x x 20 לל לל + 1948.1 Ωm x x 25 x לל לל x x 264.6 Ωm + x + + x + 30 x x x 326.2 Ωm x340 Ωm 379.2 Ω Depth (m) Depth x x x x + x x 35 + x x לל לל לל + x x + + x 40 x x xx x x x x x 45 484.3 Ωm x 556.8 Ωm x x 531.3 x x 50 x x x 899.9 Ωm x

116

Legend Location VES Aquifer type station Loam/sand soil 1 Weathered/fract - - clay ured - - (unconfined) Weathered layer 2 Weathered/fract ל + Partially weathered/fractured Orokere ured +x + basement Amuro (unconfined) x 3 Weathered/fract x x Fresh basement x ured (unconfined) 0 100m 4 Weathered layer 5 Weathered layer

Location VES Station Aquifer Types 2-D Geo-electric Sections along North South (N-S) Directions at Orokeere Okeere 1 Weathered Layer

2 Weathered Layer

W VES 5 VES 1 VES 2 VES 3 VES 4 0 389 Ωm ---- - 538 Ωm - - 110 Ωm --- 1279 Ωm- - - - 139 Ωm - - 2 - לל לל לל לל 4 לל לל Ωm 67 לל לל לל Ωm 66 לל לל לל Ωm 82 לל לל לל לל לל 6 X לל X X לל לל לל 8 1048 Ωm לל Ωm X X 38 ללΩm 110 10 + X X X X לל X X

+ X לל Depth (m) Depth 12 X X X 826 Ωm + + + לל לל לל 14 X X X 229 Ωm X X לל X X X + X X לל לל X 16 X X X X 18 X X X X X X 592 Ωm 893 Ωm + X + X X X X X X X X X X X 20

117

Legend 3 Weathered/fractured (unconfined) - - Clay 4 Weathered layer - - 5 Weathered layer Weathered Layer לל לל x x Fresh Basement x + 0 + x Partially Weathered / 100m x + Fractured Basement 2m 2-D Geo-electric Sections along West-East (W-E) Directions at Okeere

37.08 Ωm 33.32 Ωm 1741.58 Ωm 759.95 Ωm W VES 1 VES 2 VES 5 VES 3 0 − − − − − − − − x 228.79 Ωm − x x לל Ωm 88.64 לל 5 82.40 Ωm 34.27 Ωm + + x −445.88 + x לל לל 10 x 202.22 Ωm x x x לל לל לל Ωm x 744.13 Ωm 717.09 + לל 15 x לל לל לל x x x 20 x x x x + x x x x x 25 x x x x x לל Ωm 47.04 + x x x

Depth(m) 30 לל x x x x x + x x x x x לל x + x x x x x x 35 + x x 40 x x x x x x x x 634.79 Ωm 45 x x 556.92 Ωm x x x x x x 634.79 50

Location VES Station Egbe I 1

118

2 Legend 3 4 - - Clay 5 - - Weathered Layer לל לל x x Fresh Basement x + 0 + x Partially Weathered / 100m x + Fractured Basement 2m 2-D Geo-electric Sections along West East (W-E) Directions at Egbe

64 Ωm N VES 6 VES 9 VES 8 VES 7 VES 10

0 − − − − − − − − − − − − − − − 110 Ωm − − − − − − − − − − − − − − − − − − − − 18.0 Ωm 5 77 Ωm 159 Ωm − − − − − − − − − − − − − − − − Ωm −−44.7 לל לל לל − − − − − − − − − − − − 10 54.9 Ωm − − − לל − − לל לל לל לללל לל לל לל לל לל לל לל לל לל ל + Ωm 75.6 15 Ωm 40.44 + לל לל לל Ωm + x 372.4 Ωm 54.02 + x+ לל לל לל לל 20 ל ל לל + x 334.6 Ωm לל לל x לל Depth (m) Depth 25 לל x x x x + + x x לל x x 30 x + x + 404.6 Ωm x x + x x 264.6 Ωm x x x x x 514.4 Ωm x 35 326.2 Ωm x x x x x x x 506.8 Ωm x x x x 40

119

Legend

Loam/sand soil - - clay - - Weathered layer ל + Partially weathered/fractured + x basement 0 x + 100m x x Fresh basement 5m x 2-D Geo-electric Sections along North South (N-S) Directions at Egbe

233 Ωm 150 Ωm 32.9 Ωm N VES 13 VES 11 VES 12 VES 14 S 0 −−−−− − − − − −− − − − −− − − − − − − − − − − − − − − − − − − − − − − 134 Ωm x לל לל − − − − − − − − − − לל − − − − 5 x x לל לל Ωm 54.4 לל ל 10 לל לל לל לל לל לל לל Ωm 226.5 לל לל Ωm 52 ל לל Ωm 82.8 x x x לל לל לל 15 x לל לל ל לל לל 20 x x x x x x לל לל לל x x x x ל + x x לל + x 25 x + 155.6 Ωm 481.5 Ωm x 30 x+ 392 Ωm x x Depth (m) Depth x x x x x x x x x 35 + + x x x x x + x x x 40 + x x x x x + x x x 45 x x 527.9 Ωm 50

120

Legend

- - Clay - Location VES Aquifer type - station Weathered Layer ל 0 Egbe 11 Weathered 100m III layer ל x x Fresh Basement 12 Weathered x layer + Partially Weathered/ +x Fractured Basement 5m 13 Weathered + layer x 14 Weathered 2-D Geo-electric Sections along North South (N-S) Directions at Egbe layer

422.16 Ωm 366.49 Ωm 792.3 Ωm 954.94 Ωm 583.26 N VES 3 VES 2 VES 1 VES 4 VES 5 0 ------− − − - 992.17 Ωm - - - - - 90.01 Ωm לל Ωm 106.93 5 לל לל לללל לל Ωm 72.76 לל לל לל לל ל x 10 x +x x לל Ωm 79.89לל x x לל x לל Ωm 116.65 15 1094.66 Ωm + +x + x x x לל לל x x 113.09 Ωm x Depth (m) Depth x x x x x לל x x x + 1712.71 Ω לל 20 x x x x x + x x x x x + x x x + x 25 x 841.81 Ωm x x 3391 Ωm x x x x x x x x x x x + x 30

Legend

121

Location VES - - Clay - station - 1 Weathered Layer Oroke- 2 ל Efo 3 0 ל 100m x x Fresh Basement Amuro 4 x + Partially Weathered/ +x Fractured Basement 5 + 5m x p

2-D Geo-electric Sections along North South (N-S) Directions at Oroke-Efo Amuro

22 Ωm 25 Ωm 20 Ωm 80 Ωm 180 Ωm E VES 1 VES 2 VES 5 VES 3 VES 4 0 ……..………………..…………………………………... − − − ~ ~ ~ ~ ~ ~ ~ ~ … .. . ….. − − − − ~ · · ·· · ·350 Ωm 2 − − 75 Ωm ~ ~ ~ 60 Ωm 35 Ωm ~ ~ ~ 50 Ωm ~ ~ · · · · · · ·· · − − ~ ~ ~ · · ·· ~ ~ ~~ ~ ~ 4 ~ ~ − − ϟϟϟϟ ϟϟ ϟϟ xx + 220 Ωm ϟϟ + x + ϟϟ ϟ ϟϟ − − − 6 ϟϟϟϟ ϟϟ 90 Ωm 60 Ωm + x ϟϟ − − − ϟϟ + 100 Ωm 8 100 Ωm ϟϟ ϟϟ ϟϟ ϟϟ + + ϟϟ ϟϟ + x x + ϟϟ ϟϟ ϟϟ ϟϟ ϟϟ x + 10 ϟϟ ϟϟ ϟϟ + x Depth (m) Depth ϟϟ ϟϟ x + + 12 ϟϟ ϟϟ x x x + x120 Ωm x x x + x x 5000 Ωm + 14 x 1500 Ωm x x x 850 Ωm x x x x + x x 3500 Ωm + 16 x x x x x x x x x x x x x 10000 Ωm 18 x x x x

Legend

122

Loam/sand Location - - clay - - ˜ ˜ Quart vein Ayede ˜˜ ˜ Amuro Weathered layer 0 100m לל ++ x Partially weathered/fractured x + basement x x Fresh basement 2m x

2-D Geo-electric Sections along East West (E-W) Directions at Ayede Amuro

765.3 Ωm 126.58 Ωm N VES 4 VES 3 VES 2 VES 1 VES 5 S 0 --- - - לל ------Ωm 300 - - − − − − − − 557.3− - Ωm - - 163.77 -Ωm לל לל לל 5 לל לל לל לל לל x x לל לל Ωm 32.55 x x לל x לל לל לל 10 Ωm x 73.47 לל Ωm 101.12 Ωm x 124.65 לל x x לל לל x xx x x לל לל לל 15 לל Depth (m) Depth + x x 288.32 Ωm + + x + + x ++ x x x x 20 x + + x x + + x 480.79 Ωm+ x x + x x4519 Ωm x x x + + x+ + x x + x + x x x + + x + x x x x x + xx x x x + x x + x + 25

Legend Location VES station

123 2 Agbajogun

Amuro 3 4 Loam/sand soil

- - clay - - Weathered layer ל Partially weathered/fractured ++ x basement x + 0 100m x x Fresh basement x 5m

2-D Geo-electric Sections along North South (N-S) Directions at Agbajogun Amuro

198.83 Ωm 110.07 Ωm 302.25 Ωm N VES 1 VES 2 VES 5 VES 3 VES 4 0 - -- − − − − −− ------316.36 Ωm - - 248.38 Ωm - - 370.63 Ωm - 18.06 Ωm 5 7.35 Ωm 59.62 לל לל לל ל לל לל לל לל 10 לל xx x+ x Ωm 208.36 + לל Ωm 44.6 לל 15 88.91 Ωm x x x + Ωm x x 370 + לל x x + + x x לל 20 + לל לל Depth (m) Depth x + x x x x 597.37 25 x + x x x 427.07 Ωm + + x x + + לל x x + x x + x x 30 + x + + + 289.17 Ωm + x + x x+ x + x 35

Legend

124

- - Clay - - Location VES Weathered Layer station לל 1 לל Fresh Basement 2 x x 0 x 100m + Partially Weathered/ Ileteju + x Fractured Basement 3 + 5m Mopa x 4 2-D Geo-electric Sections along North South (N-S) Directions at Ileteju 5

333.92 Ωm 223.79 Ωm 647.47 Ωm 92.18 Ωm 541.16 Ωm VES 5 VES 1 VES 2 VES 3 VES 4 N S 0 ------Ωm -170.07 - --- - לל לל Ωm 5145 Ωm 44.39 לל לל - לל Ωm 38.91 לל לל לל 5 Ωm 33.21 לל לל לל לל Ωm 25.40 לל 10 x x לל לל x + x x x + + x x לל לל לל x + x לל Ωm+ x 417.19 Ωm x x 459.67 15 x לל לל x + x x x לל x ++ x + x x x x לל x x + x x x + + 20 Ωm 751.84 לל Depth (m) Depth + x x 792.54 Ωm x + x x + + x x 25 x x + x x x x x x + x x + x x x x x x לל x+ + x x x x ++ 30 x x + x x x x x x x x x x x + x + x x ∞Ω͚ m x x x x x x ͚ x 35

Legend

125

Loam/sand soil Location VES - 1 - clay Odole - - Mopa 2 Weathered layer 3 4 ל + Partially weathered/fractured 5 +x basement 0 x + 100m

x x Fresh basement 5m x

2-D Geo-electric Sections along North South (N-S) Directions at Odole Mopa

N VES 3 VES 2 VES 1 VES 4

0 --599 Ωm --- -- 01070 Ωm - 629 Ω--m 697---Ωm 0 0 0 לל Ωm 108 לל Ωm 56 לל לל לל 5 לל לל לל לל 10 Ωm + 1382 Ωm 137 לל לל לל 403 Ωm X X 15 X + X + X + X לל Ωm X 16,835 לל 20 X + + X + X X לל לל X + X X X 25 X X X + X X X לל 30 X X + Depth (m) Depth X X X X +X X לל + X X + 35 104 Ωm + X X X X X X X + X X לל 40 + X X+ +X + X X + X X X + לל 45 X X Ω + X X X 425 m + X + X 50 + + X

126

Legend - - Clay - - Location VES Weathered Layer station ל 1 0 ל x x Fresh Basement 100m x Otafun 2 + Partially Weathered/ +x Fractured Basement 5m 3 x + 4 2-D Geo-electric Sections along North South (N-S) Directions at Otafun

VES 1 VES 3 VES 5 VES 2 VES 4 W E 0 ------27 Ωm - - - 14 Ωm - --- 5 35 Ωm - - - - 35 Ωm - 233 Ωm ------10 לל לל לל לללל לל לל לל לל לל לל לל לל לל 15 לל לל לל Ωm 46.4 Ωm 50.31

Ωm 41.89 Ωm 50.31 לל Depth (m) Depth Ωm 82.7 לל 20 לל לל לל לל XX לל לל לל X לל לל X 299 Ωm X 283 Ωm 25 X X X X X X 31.4 Ωm X 310 Ωm X X X X 30 X X X446.8 Ωm

Legend

127

- - clay - - location VES 0 station 100m ל weathered layer 1 ל

x x fresh basement 5m Igbaruku 2 x 3 2-D Geo-electric Sections along West East (W- E) Directions at Igbaruku 4

N S 0 VES 1 − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − 296 Ωm − − − − − 97.0 Ωm − − −− − − − − − − − − − − − − − − − − − − − − −− − − − − − − − − − − − 5 − − − − − − − − − Depth (m) לל לל לל לל לל לל לל ל לל לל לל Ωm 51.3 Ωm 59.9 ללל 10 ל לל לל לל לל לל לל לל לל ללל ל לל 15 x x x x x x x x 481.5 Ωm x x x x xx x X 2581 Ωm x x x x x x x 20

128

Legend - - clay Location VES - - station Iyamerin 1 weathered layer ל 100m 0 ל 2 x x fresh basement 5m x

2-D Geo-electric Sections along North South (N-S) Directions at Iyamerin

NE VES 4 VES 1 VES 2 VES 5 VES 3 0 - 15 Ωm ------20 Ωm 100 Ωm 38 Ωm לל Ωm 32 0.1 לל לל לל לל לל לל 0.2 לל לל לל לל לל לל 0.3 לל לל לל 9Ωm 0.4 5Ωm 53 Ωm לל לל 0.5 19 Ωm לל X X X Ωm 286 לל 0.6 Ωm X X X 200 לל Depth (m) Depth X X 14 Ωm 190 Ω 0.7 X X X X X X X X X 0.8 X 201 Ωm X X X X X X 0.9 X X X X X 160 Ωm X X 1

129

Legend Location VES - - Clay station - - 1

Weathered layer ל 2 0 ל 100m x x Fresh basement Odo-Ara 3 2m x 4 2-D Geo-electric Sections along Northeast Southwest (NE-SW) Directions at Odo-Ara 5

E VES 3 VES 5 VES 2 VES 1 VES 4 0 - -120 Ωm - --135 Ωm - 112 Ωm - - 170 Ωm - -- 95 Ω 2 לל לל לל לל לל Ω 76 לל לל לל 4 לל לל לל לל לל Ωm 93 לל לל לל 6 לל לל Ωm 62 לל Ωm 56 Ωm 50 8

Depth (m) Depth XX X X XX לל 10 X 1500 Ωm 800 XXX לל X X X X 12 X X 1750 Ωm XX 950 Ωm X X X X X X X X 14 X X

130

Legend Location - - Clay - - 0 ל Weathered layer 100m ל

x x Fresh basement 2m x Ogbe

2-D Geo-electric Sections along North South (N-S) Directions at Ogbe

W VES 2 VES 1 VES 4 VES 3 VES 5 E 0 ------400 Ωm ------380 Ωm - - - 460 Ωm -- לל 2 לל לל לל לל לל לל לל לללל 4 לל לל לל 27 Ωm 210 Ωm 120 Ωm לל 6 Ωm 95 לל לל לל לל

Ωm 90 לל Depth (m) Depth X לל X X X X 8 X X X לל X 2100 Ωm X לל Ωm 2500 X X X X 10 X X X X X X 2150 Ωm X 2500 Ωm X XX X 1585 Ωm X X X XX X 12 X

Legend

131

- - Clay - - 0 100m Weathered layer ל Location VES ל station x x Fresh basement 2 1 m x

2 2-D Geo-electric Sections along West East (W- E) Directions at Ogbom

Ogbom 3

133 Ωm970 Ωm 780 Ωm 705 Ωm 98 Ωm 322 Ωm 8787 Ωm 317 Ωm 333 Ωm VES 4 VES 3 VES 2 VES 1 VES 5 NE 0 לל לל לל לל לל לל לל ל לל לל לל לל לל לל ל לל Ωm x x x 2751 x + x x 10 x x x + + + x x x x x x x x x123 Ωm + x + + x x x + 5092 Ωm לל 20 x+ x + לל לל + x x 4013 Ωm לל Ωm 82 Ωm x x 30002 745 לל לל 30 x + x לל x + x x + + + 40 x+ + + ++ x x x x x 76 Ωm x + 274 Ωxm x +

Depth (m) Depth 50 x + x ∞Ω m x + + + x 248 Ωm x + + x + + x 60 x x x x + x x + x x + x + x + x 70 x x + 71 Ωm + x x x x x x ∞Ω m + x ∞Ω m x 80 x x

132

Legend Location VES Aquifer type Loam/sand soil station - Ogga 1 Weathered(unconfined) and - Clay - weathered/fractured (confined) - 2 Weathered/fractured (unconfined) (Weathered layer 3 Weathered/fractured (unconfined ל Partially weathered/fractured 4 Weathered/fractured (confined) + 0 +x Basement 100m + 5 Weathered(unconfined) and x weathered/ x x Fresh basement 10m x

2-D Geo-electric Sections along Northeast Southwest (NE-SW) Directions at Ogga

133