Remote sensing and 1D geoelectric surveys for the characterization of basement aquifers in a Pan-African orogenic belt, Akak/Cameroon

Abstract This study demonstrates the importance of using a holistic, multidisciplinary approach involving remote sensing, structural field studies and vertical electrical soundings for the identification and hydrogeological characterization of lineaments in a Pan-African orogenic belt exemplified by the Akak peri-urban area, in the North-East of Yaoundé in Cameroon. Remote sensing analysis was carried out using shaded relief images and principal component analysis on bands 6,5,1 of Landsat 8 Operational Land Imager (OLI) images to obtain lineament maps. Results show that major orientations are NW–SE and NE–SW, supplemented by NNE–SSW, ENE–WSW, N–S and E–W, which was validated by structural field surveys. The lineament density map indicates the presence of a higher lineament density in the north-eastern and south-western part of the study area.Fourteen vertical electrical soundings were conducted along six profiles using a Schlumberger configuration. Results obtained highlight five to six vertical geoelectric successions, with topsoil, follow by a nodular clay layer, a semi-conducting sandy clay, a resistant weathered gneiss and a conductive fractured gneiss. This characterization suggests that semi-conducting sandy clay represents the upper aquifers found in ≈ 20 m depth with ≈ 25 m thickness, and the basement aquifer is ≈ 56 m deep with a thickness of ≈ 55 m. Drilling and pumping proved that potable water exists in the 120–140° fracture direction located in the North-East and South-West of the study area (Q = 5–10 m3/h).