Evaluation of groundwater resources and geoelectric properties using electrical resistivity method at Barakin Rafin Gora Area, Jos-Plateau, Northcentral Nigeria

Abstract

The evaluation of groundwater resources and geoelectric properties at Barakin Rafin Gora area, Jos-Plateau was carried out using electrical resistivity method. Forty (40) Vertical Electrical Soundings (VES) were carried out using the Schlumberger electrode array configuration, with half-current electrode separation (AB/2) varying from 1 to 125 m using Allied Ohmega terrameter and its accessories. The resistivity sounding curves obtained from the study area varied from the 3-layer (A and H types) to 4-layer (AK, KH, HK, QH, HA, AA and QK) and 5-layer (HKH and KHK) with the H type being the predominant. The geoelectric sections indicate that the subsurface is characterized into five (5) geologic layers namely: topsoil, weathered layer(laterite, clayey), fractured basement and fresh basement. The thickness of overburden ranges from 0 to 40m and is classified into three zones rating basically as low aquifer potential (0-5m), intermediate aquifer potential (20-30m) and higher aquifer potential (30-40m). The groundwater prospects of the study area are zoned into high (red colour), medium (pink colour) and low potentials (yellow colour). The zones where thickness of the aquifer is greater than 25m are considered zones of high groundwater potentials at VES points, 3, 9, 15, 25, 28 and 38 while the low groundwater potential rating occurs where the aquifer thickness is below 20m at VES points 13, 19, 20, 24, 28, 31, 33 and 34.