Locating Aquifers in Crystalline Granitic Rock Using Electrical Resistivity Technique in the Sissala East District of Ghana

Abstract

Groundwater prospecting in the Sissala East District has been conducted using the electrical resistivity method.  This has been done with the objective of locating suitable sites for borehole drilling and to determine groundwater potential of the district. The dipole-dipole technique of the electrical resistivity method was conducted using the McOhm 2119 resistivity meter in the horizontal profiling (HP) and vertical electrical sounding (VES) modes simultaneously. Geophysical data taken in both the HP and VES modes were presented in two dimensional (2-D) coloured vertical cross sections, from which VES curves were also plotted for selected station points and interpreted qualitatively. Results of the 2-D vertical cross sections and VES curves predicted an average depth range of groundwater or moisture interception of 10 to 15 m. The apparent resistivity of the wet boreholes was in the range of 15 Ωm and 300 Ωm. These were quantitatively confirmed with drill logs of the wet boreholes. The drill logs further showed that main aquifers and fractures were encountered between 20 m and 50 m depth range. The results yielded a success rate of about 89 %, thereby indicating that the district has a great potential for groundwater to meet their domestic and irrigation needs. Therefore, the dipole-dipole technique is effective in locating aquifers for groundwater in crystalline granitic rocks.

Keywords: Groundwater, Crystalline granitic rock, Aquifers, Apparent Resistivity