APPLICATION OF ELECTRICAL RESISTIVITY METHOD FOR GROUNDWATER EXPLORATION AT INKIL AREA OF BAUCHI, NORTHEASTERN NIGERIA

Abstract

Geoelectrical resistivity sounding using the Schlumberger array was carried out at Inkil area in Bauchi, northeastern Nigeria. The aim of this study is to investigate the hydrogeological conditions of the study area. Fifteen Vertical Electrical Soundings (VES) were carried out, from which geoelectric sections - composed of four subsurface layers – were inferred. The first layer has resistivity ranging from 58 to 2029 ohm-m and thicknesses from 0.46 to 10.7 m and is inferred to be lateritic topsoil. The second geoelectric layer has resistivity values ranging between 188 and 518 ohm-m with thicknesses varying between 14.7 and 25.8 m, this layer is interpreted to represent a highly weathered to completely decomposed crystalline rock. The third geoelectric layer is considered to be the dominant aquifer in the area under investigation and is inferred to be weathered and/or fractured crystalline rock. This layer has moderate electrical resistivity values (80–396 ohm-m), and could be recognised sometimes as the most extreme depth of current penetration. At the maximum depth of current penetration, the lower layer (fourth layer) was recognised to have the highest electrical resistivity values (451–8935 ohm. m) that depicts fresh crystalline basement. Recommended points for borehole drilling are VES 2,3,4,5,6,7,8,9,11.12.13 and 15 as they contain probable aquifers. The depth of drilling should be between 60m and 70m to take advantage of the basement fractures. In general, the area can be said to be poorly weathered and this cannot support substantial water abstraction of industrial scale when drilled