Scientists Map Africa's Groundwater to Guide Water Security for Millions

A research initiative called Groundwater for Advancing Resilience in Africa is developing a digital map that shows where groundwater can be pumped safely and sustainably. The project combines hydrogeological data on aquifer storage and recharge rates with information on population density, agriculture, and sanitation infrastructure.

Africa holds an estimated 660,000 cubic kilometers of groundwater, roughly 20 times the volume of freshwater in all its lakes combined, yet about 400 million people lack access to basic drinking water. The map aims to replace guesswork with science-based guidance for water development.

Geology varies widely across the continent. In North Africa, deep sedimentary aquifers beneath Libya, Algeria, and Egypt contain vast volumes of fossil water that fell as rain over 10,000 years ago and cannot be replenished by current rainfall. Over-extraction risks depletion and land subsidence.

South of the Sahara, groundwater resides in fractured basement rock that recharges each rainy season, providing a renewable buffer for rural hand pumps and small farms during dry periods. Pumping rates are slower due to the rock's limited pore space.

Early results indicate about 94 million rural Africans live in areas where groundwater could supply safe drinking water, with hotspots in South Sudan, Cameroon, Liberia, Guinea, Sierra Leone, and the Democratic Republic of Congo. Another 333 million people live where groundwater could support sustainable irrigation.

The map also flags risk zones: approximately 535 million Africans live in areas where human activity may be polluting groundwater, including large parts of Algeria and Libya and sections of the DRC and Angola. Water quality in these zones would require careful testing before use.

Researchers are complementing satellite mapping with fieldwork in West and Southeast Africa, where many aquifers cross national borders. Monitoring boreholes with sensors track water levels, temperature, and salinity in shared basins such as the Mono River Basin between Togo and Benin and the Shire River Basin shared by Malawi and Mozambique.

The completed map is intended to guide policy and investment decisions by bodies such as the African Ministers' Council on Water. Building modern monitoring networks that enable cross-border data sharing could help prevent conflict over shared groundwater resources.