Investigation of groundwater potential in Atan-Ota, Ogun State, South-western Nigeria

Abstract

Background: Potable water is one of the major resources that a citizen of any nation can benefit from and this is so because water is a free course of nature.  Objectives: Investigation of groundwater potential in Atan-Ota has been carried out with the objective of determining the depth to aquifer in the study area. Methods: Geo-electrical resistivity technique using both 2D and Vertical Electrical Sounding (1D) method were applied with the use of PAS earth resistivity meter. Six (6) profiles were used in  carrying out the investigation using both Wenner and Schlumberger array configuration. The data was interpreted using RES2DINV for 2D and computer iteration method (WinResist) for VES. Results: The findings showed that five (5) layer- lithologies namely topsoil, lateritic clay, clayey-sand, sand (main aquifer) and shale were delineated for VES 1 and VES 2 while four (4) lithologies namely topsoil, lateritic clay, clayey-sand, sand (main aquifer) were delinaeted for VES 3 and VES 4 respectively. The apparent resistivity for the VES 1 ranged from 360.0 Ωm to 1216.2 Ωm with corresponding thickness and depth ranged between 3.4 m and 50.2 m, and 3.5 m and 111.5 m respectively. VES 2 has characteristic type of KHA with the resistivity relationship of ρ1< ρ2> ρ3< ρ4< ρ5 and the resistivity, thickness and depth  of the lithological layers ranged from 42.5 Ωm  to 710.5 Ωm, 1.4 m to 23.2 m and 1.4 m to 48.0 m respectively. The VES 3 has resistivity, thickness and depth values ranged between 48.2 Ωm and 1825.4 Ωm, 1.2 m and 31.0 m, and 1.2 m and 70.8 m respectively. Also, the VES 4 the resistivity relationship of ρ1< ρ2> ρ3< ρ4 which of KH curve type. The resistivity values, thickness and depth ranged from 318.4 Ωm to 7634.6 Ωm, 1.7 m to 34.1 m and 1.7 m to 41.4 m respectively. Conclusions: The investigation revealed that the depth to the water-table in the study area ranged between aquifer ranges between 40 m and 111 m.

Keywords: Potable-water, groundwater, geoelectrical-resistivity, depth, aquifer