Mapping groundwater productivity in crystalline basement using VES and SRTM data: A case study of Fokoué, Cameroon

Abstract

This study focuses on the hydrogeological characterization and groundwater productivity mapping in the crystalline basement terrain of the peri-urban area of Fokoué, West Cameroon. The methodology combines satellite imagery (SRTM), with vertical electrical soundings (VES), using the Schlumberger configuration at AB/2 = 140 m, totaling 92 VES points. Lineament analysis reveals predominant NE-SW structural trends (N10°–30°, and NW315°), which correspond to major tectonic fractures influencing groundwater infiltration and storage. Resistivity values range from < 1000 Ωm (indicative of saturated clays and altered materials), to > 5000 Ωm (massive fresh bedrock). Furthermore, the electrical resistivities observed are characteristic of fractured zones, which are considered to be groundwater flow corridors. The aquifer systems are mostly semi-confined, with depths ranging from 5 to 25 m, and thicknesses from 3 to 18 m. Alongside the geoelectrical data, hydrodynamic parameters such as conductivity (K, m/day), transmissivity (Tr, m²/day), and longitudinal conductance (S, Ω⁻¹) were calculated. to access the ground water potential of aquifers. The calculated transmissivity, porosity, and hydraulic conductivity values were used to estimate the groundwater yield, revealing that over 70 % of the study area presents favorable conditions for groundwater exploitation, with an average estimated discharge of 2.41 m³ /h. This integrated approach highlights the critical role of structural control on aquifer productivity in hard rock terrains. The productivity models obtained are valuable tools for the rational use of water resources on the one hand, and on other hand, they are excellent discriminants for selecting areas favorable to the installation of water wells in Fokoué.