A Further Comprehensive Approach To Assessing The Groundwater Potential Of The Basement Complex Terrain Of Ekiti State, Southwestern Nigeria.
Bayowa O. Gabriel, Olorunfemi O. Martins, Akinluyi O. Francis, Ademilua O. Lawrence
Keywords: overburden, transmissivity, hydrogeophysical, groundwater, aquifer
ABSTRACT: Hydrogeophysical investigation as well as analyses of hydrogeomorphological, geologic/hydrogeologic, electrical resistivity and borehole data has been carried out in the Basement Complex terrain of Ekiti State, Southwestern Nigeria. This is a second and further step to validate and consolidate on the results from the earlier preliminary approach of Bayowa et’al (2014b) with a view to identifying the hydrogeologic/geoelectric characteristics of the area and classifying the area into different groundwater potential zones. The VES interpretation results were used for aquifers identification; aquifers geoelectric parameter determination and for the calculation of the overburden coefficient of anisotropy for each of the parametric VES. 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 groundwater yields of boreholes located on 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 are very low, low, moderate, high and very high. Ijelu-Ekiti, Ayede, Ipao, Ikole, Oye. Ayegbaju, Ofale-Ijero and Omuo-Ekiti were classified by very low groundwater potential 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 are however few areas with high to very high groundwater potential.
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