Journal of Geoscience and Environment Protection, 2017, 5, 213-232 http://www.scirp.org/journal/gep ISSN Online: 2327-4344 ISSN Print: 2327-4336 DOI: 10.4236/gep.2017.53015 March 31, 2017 Geoelectric Soundings for Delineation of Saline Water Intrusion into Aquifers in Part of Eastern Dahomey Basin, Nigeria Igbagbo A. Adeyemo * , Gregory O. Omosuyi, Adebowale O. Adelusi Department of Applied Geophysics, Federal University of Technology, Akure, Nigeria Abstract This study was aimed at mapping the subsurface extent of saline water intru- sions into aquifers at the eastern part of Dahomey basin, Nigeria. The study adopted geoelectric sounding methods. 108 vertical electrical soundings (VES) and 9 induced polarization soundings (IPS) data were acquired using Schlum- berger array technique. Three aquifer units were delineated across the study area. The resistivity of the first, second and third aquifer layers varies from 0.2 to 1569 ohm-m, 0.5 to 904 ohm-m and 0.4 to 665 ohm-m respectively, while depth to the top of first, second and third aquifer varies respectively from 0.7 to 151.5 m, 1.4 to 305.5 m and 12.9 to 452.9 m. The depth to the first aquifer layer is shallow (less than 5 m) in the coastal area which makes this area to be highly vulnerable to anthropogenic pollution while their proximity to Atlantic Ocean makes them susceptible to saline water intrusion. In all the three aqui- fer units, the coastal area, Agbabu and other few locations in the mainland are characterized by low resistivity values (below 60 ohm-m) indicating possible presence of brackish or saline water. IP sounding results showed that all the low resistive layers in the mainland are characterized by clayey materials. The integration of VES and IPS results enabled the delineation of the saline water lateral extent across the study area. There is a strong direct correlation (r² = 0.8564) between location distance from the saline water source and depth to saline water in the study area. This can therefore serve as a predictive model to determine depth to saline water at any location within the saline water zone in the study area. Keywords Saline Water Intrusion, Saline-Freshwater Boundary, Vertical Electrical Sounding (VES), Induced Polarization Sounding (IPS), Correlation Curve How to cite this paper: Adeyemo, I.A., Omosuyi, G.O. and Adelusi, A.O. (2017) Geoelectric Soundings for Delineation of Saline Water Intrusion into Aquifers in Part of Eastern Dahomey Basin, Nigeria. Journal of Geoscience and Environment Pro- tection, 5, 213-232. https://doi.org/10.4236/gep.2017.53015 Received: December 7, 2016 Accepted: March 28, 2017 Published: March 31, 2017 Copyright © 2017 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access