Assessment of groundwater aquifer potential zones in metamorphic basement terrains through the application of combined geospatial and electrical resistivity methods: insights from Lobo district, central Cameroon

The rapid expansion of transport infrastructure has driven significant population growth in the Lobo District, increasing the need for sustainable water resource management. This study delineates zones favorable for groundwater recharge through predictive spatial analysis, validated against geophysical datasets and observations from selected existing boreholes. Groundwater aquifer potential zone maps were generated by applying two models: the Analytic Hierarchy Process (AHP) and the Frequency Ratio (FR), based on geological, topographical, hydrological, and climatic factors. The AHP model assigned the highest weights to lithology and lineament density, followed by altitude, slope, and precipitation. Similarly, the FR model emphasized lithology and lineament density but demonstrated stronger correlations with specific altitude ranges, slope degrees, and drainage density. Despite the fact that the FR model exhibits slightly superior performance compared to the AHP model in delineating groundwater recharge zones, these two predictive spatial analysis approaches remain complementary. The former is associated with areas favorable for infiltration and recharge, whereas the latter identifies zones conducive to groundwater accumulation and storage. Vertical electrical soundings revealed curve types A, H, K, KH, HK, and HA, leading to the identification of two stratigraphic models: three-layer and four-layer formations. Lithological logs confirmed four distinct subsurface layers: topsoil, weathered/fissured bedrock, fractured bedrock, and fresh bedrock, with resistivity values ranging from 74.72 to 9,214.55 Ω·m. The aquiferous zones correspond to the second and third layers, exhibiting resistivities between 74.72 and 2,314.03 Ω·m, thicknesses ranging from 1.12 to 6.88 m, and depths between 3.9 and 42.97 m. This work elucidates the main controlling factors governing aquifer dynamics and advances the understanding of aquifer structural architecture in metamorphic basement settings. These findings provide robust evidence to guide conservation strategies and inform investment prioritization in the Lobo District water sector, thereby supporting the sustainable satisfaction of the increasing water demand driven by population growth.