Geophysical Characterization of Aquifer Parameters within Basement Complex Rocks Using Electrical Sounding Data from the Polytechnic, Ibadan, Southwestern Nigeria

Abstract

This study was carried out to characterize aquifer parameters within Basement Complex rocks using electrical sounding data from the Polytechnic, Ibadan, Southwestern Nigeria. The initiative of this study was to apply electrical resistivity and statistical techniques to delineate aquifer characteristics in the study area. The vertical electrical sounding techniques were used for the investigation. Nine types of curves were observed and the A-type is dominant. This shows that the area contains more groundwater compared to similar studies in parts of the Basement Complex of Nigeria. The resistivity of top soil varied from 40 to 1000 Ω/m with a mean of 294.33 Ω/m. Geoelectrical sections showed that a maximum of five units are below the subsurface section which include the top soil, lateritic layer, clay or weathered rock and the fractured/fresh bedrock. The reflection coefficient of the points revealed that points 1 and 3 to 15 are fractured. Fractured rocks in the area have high permeability which are caused by high weathering. Five factors: aquifer thickness, depth to aquifer, hydraulic conductivity, apparent resistivity and transmissivity were used to infer aquifer characteristics in the area. The study revealed that the area have high groundwater potential. Statistical analyses were carried out using factor, hierarchical cluster and bivariate analyses. Factor analysis revealed that all the parameters studied have influence of aquifer in the study area. Cluster analysis grouped the points into five groups of similar properties within the studied aquifer.