How Libya's Vast Underground Water Network is Depleting Ancient Sahara Reserves

Libya’s Great Man-Made River transports water from deep, ancient underground aquifers beneath the Sahara Desert to northern urban and agricultural regions. The system relies on massive prestressed concrete pipes, some reaching four meters in diameter, capable of moving approximately 2 million cubic meters of water daily.

This extensive network taps into the Nubian Sandstone Aquifer System, spanning Libya, Egypt, Chad, and Sudan. Much of the water extracted is fossil water—ancient reserves that are disconnected from the current hydrological cycle and cannot replenish as they are drawn to the surface.

Initiation of Construction in the Desert Began in 1984

Facing severe water shortages, Libya launched the project in 1983 to supply reliable water for domestic use, agriculture, and industry in coastal areas lacking sufficient renewable sources. The first construction milestone was set at Sarir on August 28, 1984.

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Two years later, the Brega facility started producing the prestressed concrete pipes essential for the network. The Great Man-Made River began delivering water for irrigation and drinking purposes to northern cities and farmlands in 1991. Before this, these regions mostly depended on desalination and dwindling coastal aquifers fed by rainfall.

This massive system extracts groundwater from deep within the Nubian Sahara’s reserves. Aquifers are subsurface layers of rock or sediment that store water, potentially for thousands to millions of years, with natural filtration occurring through soil and rock passage.

Some Groundwater Found in Libya Dates Back 40,000 Years

Large-scale underground water deposits were uncovered during Libya’s oil explorations in the 1950s. When comparing costs, pumping groundwater was more economical than importing water from Europe or relying on seawater desalination, making aquifers the preferred source.

Radiocarbon analysis established that parts of this groundwater have been sequestered beneath the surface for nearly 40,000 years, predating the last ice age. Geological shifts trapped this water, isolating it from current recharge processes and classifying it as fossil water.

A NASA Earth Observatory image dated April 10, 2006, shows a section of the Grand Omar Mukhtar water project near Suluq. The false-color satellite view highlights reservoirs and distinct irrigation patterns, such as circular fields cultivated with center-pivot systems.

The Aquifer Shared by Several Nations is a Limited Source

The Nubian Sandstone Aquifer System ranks among the world's most ancient and massive groundwater reserves. According to the International Atomic Energy Agency, its stored water volume approximates the discharge of the Nile River over 500 years—about 20 times that of the Great Lakes in North America.

Despite its vastness, the aquifer’s supply is finite and nonrenewable. As fossil water is disconnected from rainfall and other replenishing sources, extraction diminishes the total reserve permanently. The IAEA compares it to a finite resource like oil: once depleted, it cannot be restored.

In 2006, the IAEA initiated a project employing isotope hydrology to assess the aquifer’s age, flow patterns, and human impacts. This technique studies naturally occurring isotopes in water to trace its origin and movement.

The project’s initial phase developed a computer simulation that models groundwater dynamics and predicts changes in water levels over time.

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