GROUNDWATER ASSESSMENT FOR SUITABLE BOREHOLE LOCATION USING INTEGRATED GEOPHYSICAL TECHNIQUES

The increasing demand for reliable groundwater in Okitipupa, Ondo State, necessitates the use of precise geophysical methods to reduce the frequent failures of hand-dug wells and boreholes. This study aimed to assess groundwater potential and delineate borehole location using integrated electrical resistivity techniques. Seven traverses were established for data acquisition using an Ohmega R-50 resistivity meter. VES data were processed with WinResist, while 2D imaging data were inverted using DiproWin. The VES curve types (H, A, HK, and K) indicated variable aquifer conditions. Interpretation revealed three (3) to four (4) geoelectric layers comprising topsoil, clayey sand, sandy clay, and resistive bedrock. The 2D resistivity sections delineated potential aquifer zones with low to moderate resistivity values (>100 Ωm), correlating with saturated sandy and clayey sand formations. Promising groundwater targets were identified in the central section of Traverse 6 and the flanks of Traverse 1, where thick conductive layers suggest good storage capacity. High resistivity zones were associated with compacted, dry layers of poor groundwater potential. This study concluded that the integration of VES and 2D techniques proved effective in characterizing both vertical and lateral subsurface variations, thereby enhancing aquifer delineation and reducing uncertainty in borehole siting.