Integrated geophysical investigation of aquifer and its groundwater potential in phases 1 and 2, Federal University Oye-Ekiti, south-western basement complex of Nigeria

Abstract

Electrical resistivity method is frequently used in groundwater studies. It is one of the many geophysical methods used in finding, locating, and defining subsurface water. The geoelectrical survey was done in Federal University Oye-Ekiti, phases 1 and 2, south-western Nigeria, to assess the groundwater potential. Fifteen very low frequency electromagnetic traverses, three dipole–dipole profiles and three Wenner profiles and 25 vertical electrical soundings were occupied and investigated with maximum current electrode, were arranged with an equal potential spacing (AB/2) of 1–100 m with the aid of ABEM SAS 300C resistivity meter and presented as VES curves. Twenty-five VES location were evenly distributed within the study area. The VES interpretation results are of different VES curves types, namely QA, HA, KH, AH, H, KHK, KQ and AK types. The geoelectric sections delineated three to four geoelectric layers, which are the topsoil with resistivities and thickness values ranging between 113.4 Ωm and 753.1 Ωm and 0.4 and 4.4 m, respectively. The weathered layer has resistivity and thickness values ranging between 37.4 Ωm and 278.1 Ωm and 1.3 and 9.8 m, respectively. The partially weathered layer resistivity and thickness values ranging 495.1–651.1 Ωm and 10.2–22.2 m; for lateritic zones, it shows the resistivity and thickness values ranging 280.6–730 Ωm and 0.1–6.3 m. The geosections show a relatively thin overburden of less than 2.1 m. The third layer is the fractured basement. The fresh basement has a resistivity ranging between 930.5 and 4660 Ωm with depth starting from about 10 m to infinity (∞). Based on relatively thin overburden and the moderate to high fracture density of the basement bedrock, it was concluded that the groundwater potential of the study area is generally low to moderate. However, the aquifer in the north-eastern and south-eastern parts of the study area was determined to be of good quality. It can yield reasonable quantities of water that can serve the university community.