In this study, Remote Sensing (RS), Land-sat 8 digital data, and digital elevation models (DEMs) from the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER), Food and Agricultural Organization (FAO) along with other stereotypical data such as geology and rainfall were digitized and analyzed to create various thematic maps (geology, land use/cover, soil, drainage density, rainfall and slope maps) required for groundwater modelling in the study area. These thematic maps were assigned well-chosen weights and different rankings to the individual categories within each thematic map using Saaty's Analytical Hierarchy Process (AHP). The groundwater potential zones were achieved by overlaying the thematic maps using the spatial analysis tool in Arc-GIS 10.4. The result gotten was verified with pumping test data and well water levels. The results reflected that the study area had three groundwater potential zones namely, „high‟, „moderate‟ and „low‟, covering 30.27% 62.35% and 7.38% of the study area respectively, the total area is 438km2 out of which 132.58km2 is high potential zone, 273.1km2 is moderate zone and 32.32km2 is low zone. In addition, this study established that Oke-ero LGA has 65.7 million cubic meters (MCM) groundwater potential annually. From the survey output the average daily water demand in Oke-Ero is 75l/c/d, the total water demands across the LGA based on 2016 population estimate is 2.11 MCM/year with anticipated increase of 4.34MCM/year by 2040 and expected water demand increase rate of 3.2% annually. The result of correlation between final groundwater potential map and sample data from borehole yields showed90% accuracy while that of well levels indicated 84% close agreement. The results of this study set out that the GIS technology is a mighty instrument for larger area to assess groundwater potential, whereon apt locations for

 groundwater withdrawals could be indicated with greater certainty. This can be used as standard procedure for future planning and management of this paramount resource to ensure sustainable groundwater use and forthcoming magnification of drinking water and irrigation amplification in the area. Further, it is observed that the immediate methodology can be used as a clue for further research.




 1.1     Background of the Study

 It is not possible to think of any natural resource that supports human needs and economic development than water and it is the main source of fresh water availability on earth (Ravindran, 2012). The great increase in industrial, agricultural and domestic activities in recent years has resulted to increase in demand for potable water to meet the increasing demand for water. Groundwater has always been considered most suitable for this growing demand due to its chemical composition, lower level of contamination, easy exploration and wider distribution. The interaction of climatic, geological, hydrological and ecological factors is the one that resulted to variation in occurrence of groundwater at different locations on earth, it was not a matter of chance. Arkoprovo et al., (2012) said that “groundwater exploration is essentially a hydro-geological and geophysical inference operation and is dependent on the good interpretation of the hydrological indicators and evidences”.

 The freshness, lower pollution coefficient, chemical compounds, constant temperature, cost effective and higher reliability level of groundwater has made it the major source for communities, industries and agricultural uses in the world, in both urban and rural areas groundwater has been considered as a fundamental source of supplying fresh water. Recently, “about 34% of the world‟s water resources belong to groundwater and is an important source of drinkable water” (Zeinolabedinia and Esmaeily, 2015). In the world scenario, over exploitation and the deficiency of groundwater management has led to gradual reduction of groundwater availability. Now, one the world greatest problem is the

lack of fresh groundwater resource. Therefore, it is important to know the methods and various way to access groundwater potential zones, going from traditional to modern methods, practicing surface water conservation and improve the groundwater level at the urban and rural area should be improved for sustainable livelihood (Rajkamal et al.,2014).Groundwater exploration simply means searching or investigating the presence or absence of groundwater. Increasing demand on groundwater has called the attention of experts and researchers in the hydrological field of studies to find more ways of groundwater exploration. “In many parts of the world groundwater abstraction has exceeded safe yield, resulting in over exploitation and overstressing of the aquifer. Therefore, the quantum of available groundwater resource has to be assessed correctly for its optimum extraction and utilization” (Meijirik et al., 2007).


Recently, with the help of GIS technology, potential detection of groundwater resources can be done easier, more accurate and in short-time. GIS is a mighty instrument access a large number of spatial data and can be used to find groundwater potential of an areas. Many studies have been carried out through indices of groundwater potential models, some of them are as follows: frequency ratio, weights of evidence and Analytic Hierarchy Process (AHP), Zeinolabedinia and Esmaeily (2015). Several studies on delineation of groundwater potential zones using Geographical Information Systemsand Remote Sensing (GIS and RS) technologies have been conducted both in abroad (Ajaykumar et al., 2016). 
Assessment of groundwater potential in Nigeria has been carried out through delineating the aquifers by many researchers. Okoro et al. (2010) for example, evaluated groundwater potentials in parts of escarpment areas of South-Eastern Nigeria, Adewale (2017) and Akinwumiju et al. (2016) also worked on this in the South-Western and Rilwanu (2015) in North-Western Nigeria.This study evaluated the water resources of the area by analyzing effective parameters on groundwater aquifers by means of analytic hierarchy process and combining layers in ArcGIS environment. As a result of increasing in the demand of groundwater, greater emphasis is now being placed on planning and optimal utilization of the mentioned resource. Therefore, the present study concentrated on the identification of groundwater potential zones in Oke-Ero, Kwara State, Nigeria using GIS to develop groundwater prospect map for sustainable development.
1.2     Aim and Objectives

The aim of this study is to assess the groundwater potential zones in Oke-Ero LGA using GIS technique.

The objectives set towards achieving the aim of this study are to: -

i.             Development of a groundwater prospect map through the integration of various thematic maps with GIS techniques.

ii.             Determine the groundwater recharge available annually within the study area.

iii.             Determine the water demand of the area and compare it with available water.

iv.             Determine the specific yield of existing boreholes and wells water level and correlate the two with groundwater potential zones map.


1.3     Statement of Research Problems

Many studies and debates have been done on the problems opposing the protection and management of water. The spatial and temporal variations in the occurrence of rainfall at different location had resulted to the explicit meaning of water „surplus‟ and „scarce‟ river basins in Nigeria. This has brought about the thought of planning this essential resource in a more reasonable way, so that the surplus water from the „overplus‟ zone can be redirected to the deficit region. A study on groundwater resources of an area highlights the surplus and deficit areas so that appropriate and just utilization of water resources and inter-basin plans can be drawn (Rilwnu, 2015).


Because of the current need of water in the study area together with the insufficient surface water sources, there has been an enhanced interest in the use of groundwater as the whole of Oke-Ero depends principally on boreholes and hand dug wells for their water supply without any scientific record and a general map on a groundwater potential zones as a reference material.

In view of this couple with the increasing population and economic growth, many hand dug wells and boreholes that were sunk in the study area without incipient prudent investigation, and application of scientific methods later failed and so, they were forsaken.


1.4     Justification


The importance of groundwater in any nation as a major source of water supply for socio-economic development cannot be waived. Hence, the hindrance in exploration and exploitation usually faced in the areas where aquifers are both single and divided requires he use of multi-disciplinary approach involving geological and hydro-geological mapping

 Due to expanding population and economic growth, many hand dug wells and boreholes that were sunk in the study area without an incipient acceptable investigation, later failed and so, were neglected. There are several reasons for the failure of boreholes and these include inadequate or improper of pre-drilling investigation, lack of expertise on the part of personnel handling the drilling and sometimes lack of proper development of a successfully dug hole. However, the general idea about the groundwater potential, a systematic and scientific approach to the problem is therefore inherent for the study area in order to vanquish these mysteries.

 The geological characteristics of the anchor rock formation, hydrological and meteorological data are what the quantity and disposition of groundwater depends on. The search for groundwater suffer a lots of unpredictability; GIS technique was employed to abate if not eradicate failures altogether, it is important that the right exploration methods are utilized in the demarcation of groundwater bearing formations, the GIS approach will be used because in the JICA report 2014 on Nigeria water resource Master Plan, it was stated that “for any method to be suitable for evaluation of groundwater potential, the method of evaluation shall take into account not only the hydro-geological condition but also certain meteorological condition of the area”. Also, Ramu et al.,(2014) reported that the study conducted by Godebo (2005) proved that GIS and RS techniques are advisable way to find out the Groundwater Potential Zones (GPZs) among other things, it can reduce the time and cost and human power compare to the traditional methods. The purpose of this push is to provide a general knowledge and zone groundwater potential aquifers to plan, improve, manage and optimize exploitation for sustainable development in the study area

 1.5     Scope of Work and Limitation

 The scope of this project involved collecting of all relevant data of existing hydrological information, geological reports, hydro-geological, physical field measurement, presentation and analysis of data to determine the groundwater potential of the study area. The parameters (thematic maps) that contribute to groundwater potential were weighted, rated and overlaid in GIS environment and the groundwater potential map was validated.

 This work is faced with many problems such as the paucity of existing data, the high cost of data gathering and pumping test.




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