Geo-Electrical Investigation of Groundwater Resources and Aquifer Characteristics in Some Small Communities in the Gushiegu and Karaga Districts of Northern Ghana

The geo-electrical resistivity profiling and vertical electrical sounding data were acquired from some small communities and their outlying areas within the Gushiegu and Karaga Districts of Northern Ghana, in order to study the aquifer characteristics and recommend hydro-geologically suitable sites to construct water supply boreholes for the communities. The research covered four small communities, namely, Zantele, Kanshegu, Nyengbalo and Zei. The Schlumberger electrode configuration was first used in the line profiling. Qualitative interpretation of t he geo-electrical resistivity profiling data resulted in the identification of weathered regions. Vertical electrical sounding using the dipole-dipole array were then conducted with at specific points within the weathered zones. The spread length ranged from minimum of 12 m to maximum of 204 m to provide depth information. Interprex 1X1D v3 software was used to compute layered earth model of the subsurface beneath the sounding points. Interpretation of the one- dimensional inversion of the VES resistivity data provided the overburden and aquifer layering resistivities and thicknesses. The geoelectric sequence revealed predominantly a three subsurface layer which is largely congruous to the weathering profile above the fresh bedrock - thick top soil, the weathered and the variably weathered and fractured bedrock respectively. The geoelectic sections provide no evidence of a des cent into the fresh bedrock. The geophysical target is a reasonably thick and extensive zone of saturated weathered rock beneath the overburden. On the basis of the perceived aquifer properties, sites were recommended for drilling water supply boreholes for the communities.