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The Water Is Ancient, The Secrets Are Many

IAEA, Partners Help Characterise Massive Water Source Under Sahara Desert

Testing the Nubian Aquifer: water sampling in Sudan. (Photo: Dr. A. Osman)

The Nubian Sandstone Aquifer System (NSAS) is one of the oldest and largest aquifers in the world. Scientists have many unanswered questions about the aquifer, which stretches beneath four northeast African countries.

The IAEA, in conjunction with other international organisations, uses isotope hydrology to answer some of the critical questions like how long it will last and how human actions impact it; thereby strengthening policymaking and cooperation between the nations that share the NSAS.

The NSAS´ reserves are equivalent to about 500 years of Nile River discharge and are 20 times the size of the North American Great Lakes. It lies under the Sahara Desert and beneath parts of Libya, Egypt, Chad and Sudan. While the quantity of useable groundwater is plentiful it is also irreplaceable because the fossil reserves are not an active part of the surrounding hydrological cycle, meaning that the water cannot be replenished. It can only be used once - much like oil.

The Hopes of Many

Sudan and Egypt have always relied on the Nile River for the majority of their freshwater. But the Nile isn´t as abundant as it once was since more people, farms and industries have come to rely on it.

Chad and Libya on the other hand do not have access to a major river like the Nile. Surface water resources in these arid regions are scarce and diminishing.

As a result, each of the four countries has given top priority to the NSAS groundwater reserve for future demands and development planning.

Rapid population growth in both Libya and Egypt has already led to additional extraction from NSAS. Egypt needs to support the development of new cities in desert areas away from the Nile, and Libya will soon complete its "Great Man-Made River Project" to supply freshwater for Tripoli, the country´s capital.

It is possible that sometime in the future the NSAS will run dry, making it increasingly important to manage the aquifer by understanding the dynamics of the groundwater system.

Known Unknowns

Scientists are trying to find out how the aquifer works; how human actions impact it; how much water can be removed; how long it will last; where and how many wells should be drilled; and what is the effect in one country when the reserves are tapped by another.

Through isotope hydrology techniques provided by the IAEA, the answers are becoming clearer and scientists are understanding the aquifer much better.

The IAEA/UNDP/GEF Nubian Sandstone Aquifer System Project was launched in 2006, and IAEA experts are now completing the first phase, which includes observation and fact finding. The result is the development of a computer groundwater model which can simulate and predict how the water moves through the aquifer and how water levels may change over time.

"The aquifer is so deep and widespread that it is generally difficult to collect sufficient hydrologic information. Many times in isotope analysis, computer models are used as an easier way to draw the relevant conclusions. The computer model in this case will allow the countries to understand future impacts of the use of water," says Pradeep Aggarwal, Section Head of the IAEA Isotope Hydrology Section.

By using different scenarios within the model, it is possible to identify potential problems and their origins. The model is thus of critical strategic importance. The next phases of the project will involve the IAEA working with project partners and countries to create an action plan and extending technical aspects of the model to address existing NSAS policies and frameworks.


The long-term goal of the project is to establish a rational and equitable management of the NSAS for sustainable socio-economic development and the protection of biodiversity and land resources. The project´s four immediate objectives are: identify priority transboundary threats and root causes; fill key gaps; prepare a Strategic Action Programme; and establish the framework to implement said programme.

The IAEA/UNDP/GEF Nubian Project partners include: UNDP/GEF as the implementing agency; the IAEA as the executing agency and lead technical agency on the scientific component and principal co-funding agency; UNESCO and its ISARM partners as co-funding and cooperating agencies; the NSAS countries; the Joint NSAS Authority as the lead regional institution; and the Project Steering Committee, Project Implementation Unit.

Last update: 10 Dec 2020

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