Hydro geophysical Investigation for Groundwater Development at Gbongudu Area, Akobo Ojurin, Ibadan, Southwestern Nigeria

This paper presents the geophysical investigation for groundwater at Gbongudu area, Akobo Ojurin, Ibadan, Southwestern Nigeria. The area is underlain by the crystalline basement complex rocks and accessibility to potable water especially in the dry period of the year has been a major challenge. The Vertical Electrical Sounding using the Schlumberger configuration was employed. Twelve (12) vertical electrical sounding points were established in order to delineate the geo-electric layers in the area as well as evaluate the groundwater potential. The results are presented as profiles, geologic sections, curves, and maps. The VES results revealed a maximum of five geo-electric layers, viz: topsoil/lateritic sand, shale/clay, weathered layer, fractured basement and fresh basement respectively. Geo-electric sounding results were critically analyzed and interpreted. The yields of wells dug in most of these locations may be insufficient, even for domestic use because of its relatively small thicknesses. However, at a depth of 9.1 m a fracture zone occurs in VES 6 with resistivity value of 17.8 Ωm suggesting the presence of groundwater. Groundwater potential in this area is low on the average with VES 6 and VES 7 considered to be the main aquifer units suitable for groundwater exploration.

Keywords
basement complex; electrical sounding; groundwater; exploration; aquifers