AQUIFER CHARACTERISTICS AND GROUNDWATER POTENTIAL OF ARIGBAJO BASEMENT, OGUN STATE, NIGERIA

This research focuses on prospecting for groundwater, the depth at which it can be found and the quantity as well as its quality in the research area. The 2-D resistivity method was adopted. Five traverse stations were mapped and a total of sixty-four (64) electrodes were used in each station, using the ABEM Terrameter SAS 4000 and electrode selector (ES464). RES-2D package was used for analysis and the results were presented in 2-D imaging. The five stations show a resistivity range between 1Ωm to 60,00Ωm. all the stations show resistivity averaging between 10 and 100 Ωm at the depth of 30, 17, 26, 40 and 50 meters respectively. There resistivities shows the presence of groundwater, while stations 2, 3 and 4 shows that the volume is reasonably high with average of 10m thick. Stations 2 and 5 indicates that the aquifer is unconfined and at a shallow depth of 2m and 15m respectively. All the samples indicate the presence of silt, alluvia, oil sand, and sandy clay which are essential for groundwater aquifer at the aquifer depth of their respective stations. Higher resistivities between 200Ωm to about 1100Ωm which is the resistivity range for limestone, dolomite and shale (Loke M. H. 1994) was also observed at deferent depth ranging from 32m in station 1 to 22m in station 2. Resistivities of higher values above 1000Ωm which appear in all the sample is an evidence for gabbros, granite, quartzite etc. present at different depths and thicknesses.