An investigation of groundwater condition in Agbede by Geelectrical resistivity method.

Abstract

Vertical soundings (VES) for the purpose of drilling groundwater boreholes for the inhabitants were conducted in Agbede to determine: the depth to the aquifer (Ajali Formation which consists of porous and permeable coarse sandstones); the thickness of overlying aquiclude (Imo Shale which consists of non porous/ permeable thick clays) and to locate where the small lenticular sands within the Imo Shale called perched aquifer exists. Perched aquifers are hydraulically separated, are relatively small, and they occur above the water table when there is an impermeable layer of rock (aquiclude) above the main aquifer. The VES curves of the area were qualitatively interpreted and the result showed an ascent at the first decade (dry top soil), a decent at the second decade (Imo Shale) and with the right most segment ascending int6o the third decade which is an indication of the presence of the Ajali Formation below the Imo Shale. The geoelectric section from the from the VES revealed that the Ajali Formation could not be encountered even at a depth of 494.03m, indicating that the clay is as thick as 500m. Also perched aquifer could be encountered between the depths of 52.76-55.43m with thicknesses 9.89-10.86m but not in all locations.

Journal of the Nigerian Association of Mathematical Physics Vol. 10 2006: pp. 71-76