Groundwater level monitoring and recharge estimation in the White Volta River basin of Ghana

Recharge quantification is an important pre-requisite for effectively managing groundwater resources as recharge estimates are needed to determine sustainable yields of groundwater aquifers for rational and sustainable exploitation of the resource. In this study, the water table fluctuation method has been applied in the White Volta River basin of Ghana (approx. 46,000 km2) to estimate seasonal fluctuations in groundwater levels in the basin and subsequently to estimate recharge to the groundwater for the 2006 and 2007 water years. Results show high seasonal and spatial variability in the water level, with a range of 1240–5000 mm in 2006, and 1600–6800 mm in 2007. Seasonal rainfall was found to be the main source of recharge to the aquifers in the basin as water level rise occurred only in the rainfall season. Recharge to groundwater in the White Volta basin was estimated to vary between 2.5% and 16.5% of the mean annual rainfall, with a mean recharge of 7–8%.

► High seasonal variation in groundwater level, ranging between 1240 and 6800 mm. ► Seasonal rainfall is the main source of groundwater recharge. ► Recharge to groundwater varies between 2.5% and 16.5% of the mean annual rainfall.