Groundwater Recharge Estimation in Pompon Sub-Basin, Densu Basin, Ghana

Drinking water has become a challenge for many urban and rural folks in Ghana. In the Pompon River Basin which forms part of the Densu Basin, most inhabitants depend on boreholes for their domestic water supply. In addition, there had been large scale production of sachet and bottle mineral water by several companies within the basin. Despite the use of groundwater for industrial and domestic use, no study had gone into the estimation of groundwater recharge of the Pompon Basin. Hydrograph analysis of stream flow measured by a staff gauge installed on a bank of the Pompon Stream was used to derive a second order-rating curve: Y=3.3x2-2.4x +0.4 for the sub-basin. Using the Universal Soil Moisture Budget Method, estimated monthly recharge for 2001 varied from -62.6 mm in January to 81.5 mm in February. Monthly groundwater recharge as percentage of monthly rainfall varied from -62.6 % to 81.1 %. Annual groundwater recharge is approximately 295 mm. Annual groundwater recharge as percentage of annual precipitation stood at 25.6 % approximately. Thus, almost three-quarter of the annual precipitation is lost into other sources such as runoff (3.6 %), evapotranspiration (37.4 %) and soil moisture (34.4 %).