Geoelectrical and Remote Sensing in the Characterization of the Pan-African Meta-sedimentary Basement Aquifer Systems: A Case Study at Nkoteng-Elap, Central Region of Cameroon

Abstract

Abstract Nkoteng-Elap, a hamlet in the Central Region of Cameroon (Central Africa), has water issues, particularly with access to drinking water. The current study aims at (1) mapping the fracture networks of aquifers in the conceptual hydrogeological model and (2) delimiting the groundwater potential zones of the study area. A study combining remote sensing and geoelectrical measurements was carried out along profiles sub-perpendicular to the elongation of the geological bodies. Borehole and field geology data were used to validate the results obtained. The findings point to more than 300 linear structures about 0.065-74.89 km long, with two main directions: N80-100°E and N30-50-70°E. According to the Electrical Resistivity Tomography approach, there are three (03) geoelectric levels: conductive (less than 500 Ωm), semi-resistive (6500-12500 Ωm). resistive (more than 12500 Ωm), and resistant intrusive body (2050 Ωm). Existing drillings display three main lithological formations: the alteration zone, the fissured/altered zone, and micaceous quartzite. The correlation between the ERT data and drilling data reveals that the fissured or altered zone observed at 50 m is potentially aquifers. This structure is characterized by medium resistivity values (6500 Ω.m), flow rates of 1 to 3 m3/h for positive boreholes, and by low resistivity values (500 Ω.m), flow rates less than 1 m3/h for negative boreholes. The final map is categorized into five classes: very good, good, moderate, poor, and very poor groundwater potential zones. These results can help find basement aquifers and be useful in the planning and management of groundwater resources in a meta-sedimentary context.