Application of MIKE SHE software for estimation of groundwater recharge in Ogun and Oshun basins, southwestern Nigeria

Abstract

MIKE SHE software was used to estimate recharge into the aquifers of Ogun and Oshun Basins. Abeokuta within the Ogun Basin and Oshogbo in the Oshun Basin are subdivided vertically into two components: atmosphere, and unsaturated zone. The atmosphere zone comprises of rainfall and potential evapotranspiration, while the unsaturated zones, comprises of the Basement Complex and Sedimentary rock. Daily records from two rainfall stations, Oshogbo station (2008–2011) and Abeokuta station (2010–2014) water years were obtained for simulation of groundwater recharge processes using MIKE SHE model. The simulation results showed that daily groundwater recharge is influenced by rainfall and ranges from 0 mm∙day–1 in January when there was an insufficient rainfall in the two stations to 10.89 mm∙day–1 in Abeokuta and 29.85 mm∙day–1 in Oshogbo in the month of August when the soils had attained field capacity. The study found out that there are more daily groundwater recharge in Oshun basin compared to that of Ogun basin. This was alluded to more rain-fall and less evapotranspiration recorded at Oshun basin as compared to Ogun basin coupled with the sedimentary soil which allows more movement of water into the aquifer of the basin. It is recommended MIKE SHE model should be used to estimate recharge in other basins in Nigeria and Africa for quick and effective daily recharge calculations to permit better and scientific decision making in these areas.