RELATIONSHIPS BETWEEN GEOELECTRICAL AND GROUNDWATER PARAMETERS IN PARTS OF OGBIA, BAYELSA SATE, CENTRAL NIGER DELTA

The aim of this study is to evaluate the groundwater potential in Ogbia and environs, Bayelsa State using the vertical electrical sounding (VES) technique. Groundwater analysis was also carried out to investigate the water quality for both dry and wet seasons in the study area. The VES data were acquired using the Schlumberger electrode configuration. The interpreted geoelectric model results shows that the subsurface units in the area are dominated by sands of various grades with minor intercalating clay layers and has resistivity values of 50 to 395Ωm at the top of the unsaturated layer, between 13 and 352Ωm in the intermediate layers and 43 to 416Ωm in the aquiferous zones. In terms of the Dar-Zarouk parameters, the aquifers are characterized by high transverse resistance ranging from 1.2 X 10³Ωm² to 1.56 X 10⁴Ωm² and low to moderate longitudinal conductance. This implies the aquifers are highly permeable with significant specific yield and storativity. Based on the total dissolved solids (TDS), electrical conductivity (EC) and chloride concentration from the physiochemical analysis, the water facies are classified as fresh to slightly brackish. The empirical relationship developed between the bulk resistivity from the VES interpretation and (EC)^-1 from the groundwater samples using regression analysis shows variation in the benchmark for freshwater aquifer zones with respect to the season in which investigation was carried out.