Abstract

Schlumberger array is the most commonly used among other arrays for Vertical Electrical Sounding (VES) and  it requires large spacing at both ends for deeper subsurface information. The problem of limited space for spreading in built up areas could lead to incomplete information from deeper depth. The Geolectrical survey involving electrical resistivity  methods has been carried out at Birnin Kebbi and Fakai Local Government Area in Northern Nigeria with the view to delineate the Geoelectrical characteristics of basement complex and sedimentary formation to evaluate it ground water potential in the areas. A total of two (2) Vertical Electrical Sounding (VES) station were established within the site along two (2) traverses. The Schlumberger configuration was used for the data acquisition. The half current electrode (AB/2) used range from 1 to 100 meters. The quantitative interpretation of the VES curves involved the use of partial curve matching and the 1-D computer iteration technique. The depth sounding interpretation results were used to generate Geoelectric sections from which the aquifer was delineated. The Geoelectric sections drawn from the result of the interpretation revealed five (5) subsurface layers for Birnin Kebbi and four (4) layers for Fakai Local Government Area which comprises of top soil, schist, lateritic sand, partially weathered, weathered and fractured basement. The weathered and fractured layers constituted aquiferous zone in all the stations. Hence from the research work it is recommended that boreholes can be sited in high conductivity zone in VES 1 and VES 2 as they contain probable aquifers. The depth of any borehole should be located between 15m to 30m to advantage of basement fractures.