Groundwater potentials of parts of Ibiono Ibom local government Area of Akwa Ibom State Southern Nigeria by vertical electrical sounding technique

Abstract

Geophysical investigation into groundwater potential in Ibiono Ibom Local Government Area of Akwa Ibom State has been done by interpretation of modeled resistivity curves generated for the area. The vertical electrical sounding (VES) technique using the Schlumberger's electrode array with a maximum half electrode spacing (AB/2, M) of 450m was used. Eight communities were selected for the study and further classified into three main districts comprising Afaha Utuat, Oko-Ita and Ikot Obio-Okon respectively for a generalized presentation. Interpretations of the modeled resistivity curves show that in the Oko-Ita district the anomalous high resistivity of 2000 ohm-m is probably attributable to the presence of compacted clay (clay stone of not less that 30m thick. Well cuttings obtained from two (2) isolated/abortive boreholes in the area, coupled with the lithofacies characteristics observed from thick sections along orad cut further lend credence to this fact. Contrary to this, in the Afaha Utuat district, low resistivity values (200-300 ohm-m) is probably due to the presence of highly fossilized clay units dominating the area. Within these districts the probable aquifer suspected to be layer 3, occurs at a depth of 110m from the interpreted curves. Groundwater development scheme in these areas could therefore best be based on the drilling of deep boreholes not shallower than 100meters. In the alternative, surface water development schemes by tapping from available river in the area or rainwater harvesting may equally be adopted. On lthe contrary, better prospects exist in the Ikot Obio okon district where layers 2 and 3 with resistivities of 30 – 350 ohm-m constitute the main aquifers between 45 and 50m depths.

Nigerian Journal of Physics Vol. 16(2) 2004: 116-124