Geophysical Investigation For Groundwater Using Electrical Resistivity Method - A Case Study Of Annunciation Grammar School, Ikere Lga, Ekiti State, South-Western Nigeria

Abstract

Geophysical survey involving electrical resistivity methods has been carried out at Annunciation grammar school, Ikere-Ekiti, southwestern Nigeria with the view to delineate the geo-electric characteristics of the basement complex and evaluate its groundwater potential in the area. A total of 5 vertical electrical sounding stations were established within the site along 5 traverses. The schlumberger configuration was used for the data acquisition. The half –currents electrode (í µí°´í µí°µ 2) used range from 1 to 100m. 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 geo-electric sections from which the aquifer was delineated. The geo-electric section drawn from the results of the interpretation reveal five subsurface layer which comprises of the topsoil, lateritic sand, partially weathered, weathered and fractured basement. The weathered and fractured layers constituted the aquiferous zone in all the stations. Hence, from this project work it is recommended that boreholes can be sited in high conductivity zones in VES 1,2,3 and 4 as they contain probable aquifers. The depth of any borehole should be located between 15m and 30m to take advantage of the basement fractures