Quasi-3D modeling of vertical electrical sounding for mapping hard rock aquifers in the Adamawa Yadé domain, central Africa

Abstract

Exploring water resources in hard rock environments is challenging due to the approach used and the complex weathering processes that control aquifer properties, often leading to inaccurate fracture detection and high borehole failure rates. This study addresses these challenges by applying quasi-3D vertical electrical sounding (VES) techniques to map hard rock aquifers (HRAs) in the Adamawa region of Cameroon, where these aquifers are a critical water source for local communities. Using 28 unevenly distributed VES points, the research developed a quasi-3D model validated against existing borehole data and geoelectric sections. The model revealed key geoelectrical features, including metaconglomerates (1800–2100 Ω m) and a conductive HRA system with resistivity ranging from 500 to 1700 Ω m. This prominent conductive zone identified at depths of 10–40 m suggests the presence of NW-to-NE-oriented dextral strike-slip faults, which facilitate groundwater movement and create horst-and-graben structures. The study also produced a conceptual quasi-3D model illustrating variations in electrical resistivity across the aquifer system, providing a valuable tool for future hydrogeological and geophysical investigations. This model can serve as a guide for managing and protecting the aquifer system from anthropogenic impacts. The findings highlight the usefulness of the quasi-3D VES approach in identifying aquifer systems and fracture patterns in crystalline environments, offering a cost-effective alternative to expensive 3D tools, particularly in low- and middle-income countries. This approach complements traditional 1D VES techniques and demonstrates significant potential for improving groundwater exploration and management in hard rock terrains.