Groundwater Investigation Across the Crystalline Basement Rocks in Rogo Area, Kano State Northern Nigeria, Using Resistivity Methods

One-dimensional (1D) resistivity sounding (VES) and two-dimensional (2D) resistivity imaging methods were employed in groundwater investigation in order to delineate potential aquifers and estimate their transmissivities in Rogo area. Main basement rock units in the area are granites and schistose quartzite rocks of Precambrian to Lower Paleozoic age. Twelve resistivity soundings (VES) were carried out across the area using Schlumberger electrode configuration. The field resistivity sounding data obtained were interpreted with partial curve matching approach and 1D inversion algorithm, IPI2Win. The 2D resistivity imaging survey was conducted along two traverses employing dipole-dipole electrode configuration and the resistivity data acquired were subjected to finite element method modelling using DIPRO inversion algorithm to generate a geologically realistic, 2D subsurface geological model. Three to five geoelectrical layers, as well as weathered bedrock (saprolite) and fractured bedrock (saprock) aquifers were delineated. Seven resistivity sounding curve types (namely H, HA, HK, KH, QH, HKH and KQH) were also identified with the H and HA types being the dominant curve types. Anisotropy coefficient (λ) values ranged from 1.03 to 2.65 with a mean of 1.31. Aquifer transmissivity computed for the weathered bedrock aquifer units varied from 16.01 to 53.3 m /day, with an average value of 30.91 m /day. The study revealed that the Rogo area has moderately high aquifer transmissivity and hence generally exhibits good groundwater potentials.