3D modelling and characterisation of ferralitic basement aquifers by combining resistivity, chargeability and remote sensing data in the Messondo area (SW- Cameroon)

Abstract

An investigation combining remote sensing (Landsat 8) images and ground geoelectricity was carried out in order to remedy deficit in water resources in the Messondo area located in the Nyong and Kelle division, Centre Region, Cameroon.in this region, an . The remote sensing results presented respectively as fractures, fracture density and land use maps, allowed the delineation of densely fractured zones of the basement, which are favourable areas for infiltration and hydraulic capture. These zones are used to guide the geophysical work. The ground geoelectricity combined a 4-line DC and IP tomography survey-oriented SE-NW, boreholes and electrical Schlumberger profiling. After data acquisition, the study identified several conductive anomalies mainly due to the iron bearing gneisses of the basement that would be discriminated between zones of water accumulation and zones of mineralogical concentration. . . The 2D inverse modelling of the geoelectric data depicted the vertical and lateral variations of resistivity and chargeability. The joint analysis of the of these two parameters, combined with the geological observations from the area, allowed the discrimination between the aquifers and the mineralised zones. The 3D models obtained by combining the 2D models then interpolating, permitted to visualise and quantify the aquifers identified in the investigated area. . These models make it possible to distinguish two levels of water accumulation : the first level, spreading over the entire surface, is contained in the porous alterites and forms the surface aquifers that extend to a depth of 39 m, thus defining the thickness of the altered layer. The second level exclusively located to the east of the area, is contained in the fissured gneissic formations.