Characterization of the basement aquifers over Edéa-Kribi corridor using remote sensing and electrical resistivity method—a case study from Central Africa

The access of safe groundwater in the regions made up of crystalline basement terrains, as it is the case along the Edéa-Kribi corridor (Central Africa), is a challenge. The study of fracture networks is fundamental for groundwater research. This paper aims to (1) map structural lineaments that could develop underground aquifers in metamorphic rocks and (2) characterize the structure and geometry of these aquifers using remote sensing, drilling, geology and geophysical data in this region. Geo-structural method based on photo-interpretation of topographic data was used in the structural mapping of the lineament features that were validated by geological fracture map. Vertical electrical sounding (VES) and horizontal electrical profile (HEP) techniques were used to highlight the subsurface resistivity distribution and identify the geometry of the groundwater potential areas. This geometry was validated by lithological and depth drilling cuts. The results show that the tectonic control of the underground flow is supported by the fracture networks N10-55, N45, E-W, N80-100, N110, N145, N170 and N310. Also, three conductive zones corresponding to three anomaly forms (U, V and H) are distinguished. The fracture networks contain deep basement aquifers from 19 to 55 m with hydraulic flows varying between 2 and 10 m 3 /h and characterized by U and V electrical anomaly forms. They are covered by a layer of overburden (clay-sandy or clayey lateritic) deep of 9 to 20 m allowing the storage and filtering of infiltration water. Furthermore, the aquifers identified in the H anomaly form are located in the depth higher than 40 m and have hydraulic flows ranging from 1 to 5m 3 /h. Finally, the aquifers with higher productivity (between 4 and 10 m 3 /h) are obtained in the N10-55 directed fractures and related to the presence of electrical anomalies of types U and V at those locations.