Groundwater Occurrence and Aquifer Vulnerability Assessments in Coastal Settlements of Araromi Seaside and its Environ, Southwestern Nigeria

Abstract

The groundwater potential and aquifer vulnerability study of Araromi Seaside are reported in this study using a combination of Vertical Electrical Sounding (VES) and Electrical Resistivity Tomography (ERT). Double dipole with minimum electrode spacing of 20 m and maximum length of 400 m were employed to acquire twelve (12) ERT data while Schulumberger configuration with maximum half current electrode separations of 500 m was used to obtain the twelve (12) VES data at the mid-point of each ERT traverse. ERT data was inverted using DIPPRO for window software why VES curves were iterated using WINRES software. Interpretation of the ERT results show promising groundwater potential points under ERT line 1, 4, 6, 8, 11 and 12, while the VES result revealed good sandy / clayey sand aquifers with good aquifer thickness under VES 1, 2, 3, 6, 7, 10, 11 and 12. In terms of aquifer vulnerability capacity, VES 3, 5, 8 and 11 show poor capacity, VES 10 and 12 weak capacity, VES 2, 4, 7 moderate and VES 1, 6, 9 show good capacity. For healthy water supply, groundwater boreholes should be developed in areas with good aquifer parameters and good protective capacity. Juxtaposing the two parameters we suggested VES 1, 2, 6 and 7 which have both groundwater potential and vulnerability capacity for groundwater borehole development. Considering spatial result that the ERT affords, other possible point like surface position 170 m on Profile 4 is also recommended, because it satisfies the two conditions of good aquifer and good vulnerability capacity.