The North Western Sahara Aquifer System – SASS

Operational Recommendations for a Sustainable Management of the SASS Water Resources

The North Western Sahara Aquifer System (NWSA), better known under the acronym SASS for its French name Système Aquifère du Sahara Septentrional, is a large aquifer shared by Algeria, Libya, and Tunisia. The NWSAS designates the superposition of two main deep aquifer layers: the Intercalary Continental (IT) and the Terminal Complex (TC).

The use of this aquifer dates back to many years, first by creating surface wells and “foggaras” (ancient type of water supply) and later by constructing deeper “foggaras” that exceeded in certain cases one thousand meters.

The North Western Aquifer System covers an area of more than one million square kilometres and contains considerable but partly renewable and inappropriately used water resources.

The intensive use of the SASS by the three countries (illustrated by the model developed by OSS) has caused stress on the resource, increasing the risks of saltwater intrusion and salinization, loss of artesian pressure, the depletion of natural outlets and the lowering of the water table.

The SASS zone covers different eco-regions varying from desert zones (with annual rainfall rate less than 100mm and an evapotranspiration rate higher than 3000 mm) to arid zones (annual rainfall of 100-200 mm and an evapotranspiration rate of 2000-2500 mm).

Water demand 

During the second half of the 20th century, the intensive use of the SASS water resources increased and resulted in a significant increase of water demand that went from 0.6 to 2.5 billion m3/year in the three neighbour countries due to a lack of communication and consultation among them on the main risks of overuse and miss management of the SASS valuable water resource.

The projections of the increasing pressure on these resources for the few coming decades are even more alarming. The two tables below respectively illustrate: 

Table 1 - The projections of the irrigated surfaces in the three SASS countries in 2020 and 2050

Table 2 - The projections of the demographic evolution in the three SASS countries in 2020 and 2050.

Projections of the irrigated surfaces evolution in the SASS region

Country Surface (ha) in 2000 Surface (ha) in 2020 Surface (ha) in 2050
Algeria 170 000 300 000 340 000
Tunisia 40 000 55 000 70 000
Libya 40 000 77 000 103 000
Total 250 000 432 000 513 000

Demographic Projections (number of inhabitants of the SASS region per country)

Country Surface (ha) in 2000 Surface (ha) in 2020 Surface (ha) in 2050
Algeria 2 600 000 3 700 000 4 800 000
Tunisia 1 000 000 1 800 000 2 300 000
Libya 1 200 000 1 500 000 1 700 000
Total 4 800 000 7 000 000 8 800 000

An over-used water source

A survey conducted in 2011 in Tunisia showed that the irrigated surface in the Tunisian SASS part has reached more than 52 000 ha. The same thing was equally observed in Algeria. The overuse of the SASS basin led to a complete depletion of most of its water resources, loss of artesian pressure, lowering of the piezometric level, and water degradation due to salinization.