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From the Winter Issue "Africa's Moment"

By Adam Scholl

Across Africa, deep beneath a host of varied terrains, vast groundwater reserves lie almost untouched. These aquifers are some 410,000 cubic miles thick and contain 100 times the freshwater that exists on the continent’s surface. As Africa’s population expands, these aquifers could prove critical in increasing food production, reducing poverty, and adapting to climate change. 

Last April, scientists published the first comprehensive map of African groundwater reserves in the journal Environmental Research Letters. In the image above, World Policy Journal shows these water resources alongside historic drought conditions in an effort to define the enormous scope of this vital resource. Much of the groundwater lies beneath the Sahel belt, one of the most drought-prone stretches on the planet. Since water scarcity in the Sahel will remain a problem, tapping these hidden freshwater reserves could become a priority. 

Some countries have successfully exploited these gigantic fossil reserves in the past. In 1984, Libya’s surface freshwater was becoming contaminated with saltwater, so Muammar Gaddafi ordered construction of a $25 billion “Great Manmade River” project to extract water from beneath the Sahara and bring it to cities near the sea. Some estimates suggest that despite its price tag, this method was still one-tenth the cost of the alternative—desalinating water from the Mediterranean. Though the “river” works for now, large government subsidies are still the only way most Libyan farmers can afford water to irrigate their crops. And contrary to Gaddafi’s claim that the aquifer would last 4,625 years, independent research has indicated that it will run dry in just 60 to 100.

Many specialists say drilling fossil reserves should only be a last resort. They are costly to tap, and once they are gone, they are gone forever. Still, last-ditch options like the Libyan strategy could appeal to countries suffering from droughts when there is an abundance of clean freshwater beneath their feet. 

Alan MacDonald, a hydrogeologist at the British Geological Survey and the lead author of the groundwater study, argues that it is more important to tap smaller, shallower reserves. The Saharan fossil reserves are far underground, making their water expensive to extract and deliver. Furthermore, unlike their shallow cousins that refill with rainfall, these deep aquifers are not renewable—they have not recharged in 5,000 years. 

The shallow aquifers outside the Sahara, on the other hand, are relatively abundant and easy to access. Though they do not have enough water to support large cities or the type of extensive irrigation systems used in regions like the American Midwest, the map displays countless places where extraction is possible for drinking water or small-scale irrigation. Since groundwater does not fluctuate much with rainfall, aquifers of any depth can be a lifesaving asset—especially as climate change increases the likelihood of drought.

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Adam Scholl is an Editorial Assistant at World Policy Journal.