Hydro-geophysical investigation of Bauchi and environs NE of Nigeria

Abstract

Seven Schlumberger vertical electrical soundings (VES) and Fifteen Seismic refraction profiles carried out around Bauchi and its environ have been interpreted. The resistivity data were first interpreted using conventional partial curve matching technique in order to obtain the initial model parameters. The model parameters obtained were used as input into an optimizing computer program. The results obtained from VES 6 and 7 displays the presence of three-layer earth model. The first layer consists of loose topsoil materials, the second is weathered and/or fractured basement, while third layer is the bedrock. However VES1-5 display four-layer earth model, whereby the thickness of the weathered and/or fractured basement is over 19 m, except VES2 where the thickness is 8.7 m. The results obtained from the fifteen seismic refraction profiles indicate also a three-layer model. The first layer represents the topsoil with an average velocity of 146 m/s and a mean thickness of 3.1 m. The second layer has an average velocity of 1809 m/s and a mean thickness of 13.6 m. This represents the weathered/fractured basement. The third layer has a mean velocity of 4496 m/s, and represents fresh basement. From the Hydrogeological studies of borehole data, a mean depth to water table of 4.12 m, a mean hydraulic conductivity of 0.91 m/day and an average transmissivity of 19.88 m2/day, were recorded. Finally the geochemical analysis for hand-dug wells indicates a mean value of Chlorite and hardness of 186 and 381 mg/l respectively. The results from this study will no doubt serve as background information for groundwater prospecting and subsequent exploitation. Keywords: geology, hydrogeology, resistivity and seismic refraction data interpretation of Bauchi and environsGlobal Journal of Geological Sciences Vol. 3(2) 2005: 143-151