DELINEATION OF GROUND WATER POTENTIAL USING ELECTRICAL RESISTIVITY METHOD IN OROGUN, DELTA STATE – NIGERIA

Abstract

Vertical Electrical Sounding was utilized to delineate the aquifer pattern of three communities in Orogun. Six locations were used studied with current electrode spacing of AB/2 with maximum of 100m and electrode Spacing of 0.5m to 10m. The equipment used iswas the ABEM Tarrameter with inbuilt booster which was used to acquire the data. The result shows four geophysical layers in all locations. The Shallowest aquifer was found at VES 4 of 6.8m and the highest VES 1 of 16.7m. the aquifer depth fall within the ranges of 6.8m to 16.7m. The resistivity values for all the layers in the study area are moderate, the highest is at VES 4 (866.1Ωm) and the lowest at VES 1 (63.6 Ωm). To ascertain the aquifer potential, the formation parameters were also evaluated, and it reveals that the longitudinal conductance values < 0.2 except VES 1 and 2. This showed aquifer protective capacity at Ves1 & 2 are moderate but VES3-6 have weak protective capacity. The parameters also reveal high-resistivity formations, with the reflection coefficient values range from 0.535 to 0.952 for all the VES locations. The value of Resistivity contrast for VES 1–6 (2.52 to 40.41) revealed polluted especially from hydrocarbon sources and other manmade pollutants. The physicochemical parameters show that pH fall within 6.50–6.90 (mean 6.6) moderate, conductivity 9.80–22.40 μS/cm (mean 19.1 μS/cm) low, temperature 28.42–28.47°C (mean 28.3°C) moderate but Turbidity 9.50– 15.00 NTU (mean 12.17 mg????⁻¹) is very high as compared to Standard Organization of Nigeria (SON) permitted limit of 5NTU. The major ions Cl^-, SO₃^-, NO₃, PO₄^-, No₂^-, Pb, Cd, Fe, Ni and Zn respectively, revealed that all cations studied were not above the world health organization standard and Standard Organization Of Nigeria(SON) permitted limit except Cd²⁺ and Pb²⁺  which is slightly above the permitted limit of 0.003 and 0.01 mg/l. hence the water is conducive for drinking.