Hydrogeology and Physico-Chemical Quality Assessment of Groundwater in Oke-Oyi Area and Environs, Kwara State, Nigeria

Abstract

An appraisal of the groundwater potential as well as its potability in Oke-Oyi area and its environs was undertaken. This was done in order to provide information on the evaluation of groundwater system in the area as well as on the physico-chemical quality of the groundwater for domestic and Agricultural purposes. The Study entails analysing pumping test data in order to compute the hydraulic characteristics of seven boreholes in the area. Fifteen groundwater samples were also collected from boreholes and hand-dug wells in the area and analysed for their physical and chemical properties.The two aquifer units in the area are weathered overburden aquifer and fractured crystalline aquifer. The boreholes tapping these aquifers  have yields that range from 43.2m³/day to 103.7 m³/day with a mean value of 58.01 m³/day, hydraulic conductivity values range between 1.17×10^-1 m/day and 8.60 ×10^-2 m/day with a mean value of 6.27×10^-2 m/day. Transmissivity varies from 0.95m²/day to 3.16 m²/day with an average value of 1.77 m²/day. The storage coefficient (S) calculated shows values that range from 0.619 to 1.765 with a mean value of 1.238. Results obtained from the physico chemical analysis of the groundwater in the area shows that the physical parameters such as colour, taste and odour are within the acceptable limits of WHO (2006). Also, the major ions analysed are Ca, Mg, Na, K, Fe, SO₄, NO₃, Cl, CO₃ and HCO₃ and are all below the acceptable limits of WHO (2006). Hence the groundwater of the area is largely characterised as Mg-HCO₃^-Cl and Mg-HCO₃.The groundwater of the area has a low-medium salinity hazard and low sodium hazard, indicating that the groundwater is good for Agricultural purposes.The groundwater has a high recharge potential due to its low storage capacity. Also the groundwater is potable for domestic and Agricultural purposes, based on the physical and chemical parameters of the groundwater analysed which are within the acceptable limits of WHO as well as low-medium salinity hazard of the groundwater.

Keywords:Hydrogeology.  Groundwater Potential and potability. Oke-Oyi area and its environs. Physico-Chemical. Nigeria