Geoelectric Method for Investigating Saltwater Intrusion Into Freshwater Aquifer In Deghele Community Of Warri South Local Government Area Of Delta State

A geophysical investigation was been conducted using the Vertical Electrical Sounding (VES) by adopting the Schlumberger array in Deghele Community, Warri South West Local Government Area of Delta State to study the saltwater intrusion into the subsurface freshwater aquifer. Seven vertical electrical sounding were carried out. Qualitative interpretation of Vertical Electrical Sounding (VES) data revealed five to six layers, HAA, QHKA, HAK, HK, KQH and HKQ type curves. The geoelectric section delineates geoelectric layers which include saline topsoil with thickness ranging from 1.2m to 3.9m, Silty sand with thickness ranging from 2.4m to 21.6m, Sand (saline) with thickness ranging 7.9m to 50m and sand (coarse grain) with thickness ranging from 37m to 50m. These are in agreement with the lithology from borehole logs in the study area. Analysis of borehole water samples indicate that VES6 and VES7 location have high level of Chlorine and bicarbonate having ratio of chloride to bicarbonate (Cl- /HCO3-- > 2) greater than 2 which is a criteria for recognition of seawater in groundwater.