Using Electrical Methods for Groundwater Reservoirs Exploration in Cristalline Area of Man (West Côte d’Ivoire)

Abstract

In West Africa, drinking water supply relies on the hard-rock aquifers. In Ivory Coast, the population growth along with the climate changes make drinking water resources highly vulnerable. Hard-rock aquifers, which occur within the weathered and fractured zones, are important groundwater resources in tropical region. These aquifers complexity, the lack of exhaustive studies lead to bad boreholes points siting. Geophysical investigations are used to obtain information about the crystalline basement rocks, which relates to the occurrence of groundwater. In Tonkpi region (western Côte d’Ivoire) is located such aquifer, poorly known, both in its reservoir’s geometry and in the hydrogeological potential of the reserves it contains. This work deals with combining resistivity profiling, vertical electrical sounding with surface 2D geoelectrical resistivity mapping to characterize the ground and aquifers in a crystalline basement complex area of the Tonkpi region. Results allow to precise the local thicknesses of the 3 main units of our study area down to 50 m, being from top to down, saprolite, fissured-rock zone and rock substratum. The study shows that Schlumberger and Wenner alpha arrays for vertical electrical soundings integrated with the resistivity profiling imaging is efficient and enhances the aquifer characterization in basement complex terrain.