Environmental indicators of recharge to basement aquifers of Tanzania

One of the main uncertainties surrounding the impact of climate change in Africa is its effect on water supplies. Adding to this uncertainty is a lack of information on recharge to the weathered basement aquifers and how these aquifers respond to rainfall and abstraction. Residence time indicators (such as CFCs) which can indicate the amount of modern recharge in abstracted groundwater, can be a helpful first step in identifying whether active recharge is occurring. Simple chloride balance techniques are also useful to provide an indication of the proportion of recharge. We report the results of using these environmental indicators in the Singida area of Central Tanzania as part of a wider study of groundwater chemistry in the basement aquifers.