DELINEATION OF AQUIFER DEPTHS AND ITS CHARACTERISATION USING GEOPHYSICAL METHOD
1.1 BACKGROUND INFORMATION
Water is an essential liquid to human lives and continuous existence of the ecosystem. Water has some physical characteristics that guaranteed its wholesomeness: it must be colourless, odourless, tasteless, and readily foam with soap or detergents. The human body and blood are composed of 60-75% of water as such needed enough water; at least 2-3 litres for adult to enhance the effective functioning of the circulatory and metabolic systems of the body. Safe water must be used for domestic (drinking, washing, bathing, and cooking), agricultural, industrial processes, and recreational activities. This water is gotten from sources such as: rain, snow, stream, lake, river, sea and aquifer (groundwater). Safe water is dependent on the chemical components of the water. The understanding of aquifer geometry, its characterization and delineation were the major objectives of this work. Groundwater is an important natural resource that supplies billions of gallons of water for domestic, agriculture, industrial purposes and other uses. The known surface water bodies in the area under study are severely polluted by anthropogenic activities, as such about 85% of the population of the area now solely depends on groundwater as their source of water. Thus, harnessing and preservation of clean and safe groundwater becomes imperative. The considerable thickness of the aquifers, the high transmissivity of water through these aquifers due to the high degree of porosity and permeability and the adequate groundwater recharge capacity enhanced by the high annual rainfall in the area, makes the aquifers of the area reliable water resources that can yield and supply reasonable millions of volume of water to satisfy the water needs of the people and industries of the area through both public and private abstractions (Todd, 1959; Krivochieva and Chouteau, 2003, Tamunobereton-ari et al, 2010a; Tamunobereton-ari et al, 2010b). The characterization and delineation of aquifer in the area becomes imperative as water samples from some existing wells and boreholes in the study area fall short of the acceptable characteristics of groundwater and during the dry season most wells and boreholes drop to a minimum yield and sometimes get dried up; perhaps due to lack of hydrogeological information of the area and improper delineation of the aquifer to facilitate the precise identification of desired aquifer before drilling and well completion for sustainable supply of potable water to the people of the area (Edlefsen, and Anderson. 1941; Tamunobereton-ari et al, 2013).
1.2 OBJECTIVESAND SCOPE OF THE STUDY
The objectives of this research work are to:
(1) Determine the lithological succession and the prospective water bearing horizons in terms of resistivity, thickness and depth across the study area using vertical electrical sounding method
(2) Evaluate hydraulic conductivity and transmissivity of aquifers in the study area using Da-Zarouk parameters from vertical electrical sounding
(3) Compare the value of aquifer hydraulic conductivity obtained from this study with that obtained by pumping test method using statistical correlation tool.
(4) Assess the overall groundwater potential across the study area
(5) Assess the level of protection of aquifers in the area from surface pollutants(aquifer protective capacity) using Da-Zarouk parameters from vertical electrical sounding
(6) Correlate geoelectric sections in the study area with existing borehole logs.
(7) Determine groundwater flow direction using existing well data and elevation values.