Urban groundwater development in sub-Saharan Africa

The urban population of sub-Saharan Africa is growing at a faster rate than in any other region in the world. Efforts to supply potable water to rapidly urbanising centres commonly target groundwater on account of its perceived potability that necessarily avoids the high treatment costs which are associated with surface-water sources. Groundwater is supplied through spring discharges, manually pumped wells (<0.2L/s), and more intensively pumped, production boreholes (>0.2L/s). Despite the costs of constructing groundwater-fed waterworks, the impact and viability of abstraction are unknown and typically subject to cursory assessments prior to development. Furthermore, the susceptibility of groundwater-fed water supplies to contamination in the urban environment, where the subsurface acts not only as a supply of water but also a repository for sewage and industrial effluent, has not been rigorously studied. This paper highlights key uncertainties regarding weathered aquifer systems in sub-Saharan Africa such as hydraulic conductivity, aquifer storage, recharge, contaminant attenuation and drawdown due to pumping which affect the development of groundwater in the urban environment. Recommendations for research to improve understanding of urban groundwater development in this setting are provided