A three-dimensional numerical groundwater flow model to assess the feasibility of managed aquifer recharge in the Tamne River basin of Ghana

Abstract

AbstractIncreasing population growth and global climatic changes threaten water security in semiarid regions such as Northern Ghana. The Tamnean Plutonic Suite aquifer is the main source of water supply for the inhabitants of the Tamne River basin, which is a transboundary subbasin of the White Volta Basin, Ghana. The basin is a flood-prone area where flooding occurs every rainy season, but there is water scarcity during the dry season, mainly due to poor groundwater resources planning. It is expected that the population will increase in the next 10 years, implying a greater water demand. A steady-state and transient groundwater flow model has been developed to understand the hydrogeological conditions and assess the feasibility of managed aquifer recharge (MAR) in the area. A single granitic aquifer formation was delineated from the three-dimensional lithology modelling. The calibrated aquifer recharge through precipitation is very low due to high evapotranspiration and low rainfall. A MAR injection scenario was tested using the available treated floodwater that is registered during the rainy season in the area. The results show the total volume of water injected at the end of the 4-month study period is 11,000 m3/day (approximately 1.3 × 106 m3), which significantly increases aquifer storage and groundwater levels. The volume of water recovered at the end of 8 months (1.4 × 106 m3) is enough for domestic and irrigation purposes during the dry season. In general, MAR is feasible in augmenting the water levels in the area when combined with controllable irrigation and domestic withdrawals.