Geoelectric Evaluation of Groundwater Potential and Vulnerability of Overburden Aquifers at Onibu-Eja Active Open Dumpsite, Osogbo, Southwestern Nigeria

Abstract

Electrical resistivity method was used to assess groundwater potential and vulnerability of overburden aquifers at Onibu-Eja active open dumpsite, Osogbo, Southwestern Nigeria. Eighteen Vertical Electrical Sounding (VES) points and five 2-D imaging profiles established in five traverses at the periphery of the dumpsite were surveyed and analysed. The subsurface comprised of thin topsoil (resistivity 65 - 998 Ωm); heterogeneous weathered layer with resistivity 63 - 333 Ωm and thickness 0.7 - 8.5 m; weathered basement (resistivity 31 - 1253 Ωm and thickness 0.7 - 27.0 m) and fractured/fresh basement (resistivity 36 - 6213 Ωm). The 2-D inverse model of the profiles delineated low resistivity values ranging from 5 to 100 Ωm at a depth range of 10 - 20 m along traverses TR1-TR3 which is attributed to leachate percolation close to the dumpsite. The weathered basement was inclined relative to the dumpsite...