Integration of hydrogeophysical and remote sensing data in the assessment of groundwater potential of the basement complex terrain of Ekiti State, Southwestern Nigeria

Abstract

Hydrogeophysical investigation as well as analyses of hydrogeomorphological, geologic/hydrogeologic, electrical resistivity and borehole data had been carried out in the Basement Complex terrain of Ekiti State, Southwestern Nigeria. This was with a view to classifying the area into different groundwater potential zones. The VES interpretation results were used for aquifer identification; aquifer geoelectric parameter determination and for the calculation of the overburden coefficient of anisotropy. Hydrogeomorphological, lineament density, lineament intersection density and overburden coefficient of anisotropy thematic maps were produced and integrated for the classification of the study area into different groundwater potential zones. The reliability of the groundwater potential map was checked with the existing groundwater yield data. The weathered and fractured basement constituted the main aquifer units. The groundwater yields of boreholes located within quartzitic rocks had a mean of 1.56 l/s while the mean groundwater yield from metasediment (schist) was 1.14 l/s. The study area was characterized into five different groundwater potential zones which were very low, low, moderate, high and very high. Ijelu-Ekiti, Ayede, Ipao, Ikole, Oye. Ayegbaju, Ofale-Ijero and Omuo-Ekiti were classified as very low groundwater potential areas while low groundwater potential was established in Ijesa-Isu, Iludofin, Iyemero, Esure, Otun, Osi, Iropora, Ifaki, Ikun, Ijero, Ado, Emure and Ise/Orun. Igbara-Odo, Ilawe, Ikogosi, Ido, Ipole-Iloro, Ipere, Ayetoro, Ikoro, Ifisin, Ilogbo, Isinbode, Erinmope and Iwaro fall within moderate groundwater potential zones. High groundwater potential was recorded in Ijan, Okemesi, Aramoko, Ilemeso, Ikere, Etisun and Itawure. Efon-Alaaye and Ilumoba fall within very high groundwater potential zone. The groundwater potential of Ekiti State is generally of very low–moderate level rating. There were however few areas with high to very high groundwater potential.

Keywords: Basement Complex, Hydrogeophysics, Remote Sensing, Groundwater Potential, Ekiti State.