The Sahara is famous for being one of the driest places on Earth. However, enormous amounts of water are hidden beneath parts of the desert.
Deep underground, layers of porous rock hold groundwater in vast natural systems known as aquifers.
Some of these aquifers stretch beneath several African countries and have supplied communities with water for generations.
How did water get beneath the Sahara?
The Sahara was not always as dry as it is today.
During wetter periods in the region’s past, rainfall soaked into the ground. Over time, some of this water accumulated deep inside layers of permeable rock.
As a result, some groundwater beneath the Sahara has remained underground for thousands of years.
This means that beneath today’s extremely dry landscape, water from much wetter periods can still be found.
One aquifer stretches beneath four countries
One of the Sahara’s most important underground water systems is the Nubian Sandstone Aquifer System.
It extends beneath parts of Chad, Egypt, Libya and Sudan.
Because the aquifer crosses national borders, the countries share an interest in understanding and managing this underground resource.
Another major system is the North Western Sahara Aquifer System, which extends beneath Algeria, Libya and Tunisia.
These enormous systems show how groundwater beneath the Sahara can stretch across vast distances.
Why can’t all the water simply be pumped out?
Having huge quantities of groundwater beneath the desert does not mean the supply is unlimited.
Some Saharan groundwater replenishes extremely slowly. In certain areas, much of the water accumulated during wetter periods thousands of years ago.
If water is extracted faster than it is naturally replaced, groundwater levels can fall.
Water quality can also differ between locations.
For these reasons, careful management is important when countries use groundwater for drinking water, agriculture and other needs.
A hidden resource beneath the desert
From the surface, much of the Sahara appears almost completely dry.
Yet beneath parts of the sand and rock are vast groundwater systems extending across several countries.
They provide an important source of water in one of the world’s driest regions.
It is one of the Sahara’s most surprising features: beneath the desert lies an enormous hidden supply of water.