Management of internationally shared groundwater resources in North Africa (SASS)

The North Saharan Aquifer System (SASS) is a groundwater resource shared between Algeria, Tunesia, and Libya. Today it receives virtually no recharge. It is overexploited, a fact which shows in vanishing Artesianism and decline of spring flow. Although this situation is not sustainable one may still argue that the resource can be mined, especially as the amount of water is large enough to last for 500 to 600 years at projected consumption rates. However, the resource comes at a price, which is growing in time. It consists of the energy and investment for lifting the water and distributing it on one hand and impairment of quality on the other hand. Salinity is rising due to attraction of salt brines from Chotts, the underlying Turonian and irrigation backflow. The project seeks to optimise the price over a given time horizon by choosing new wellfield locations, time varying pumping rates, and a shift of abstractions from the already drawn-down CT-aquifer to the CI-aquifer. The optimization method used is a genetic algorithm. It is adapted to the problem as the number of degrees of freedom is very large and no other method is similarly efficient in finding an optimum. Production functions are determined by investigations in the main oases in Tunesia. A detailed study about causes of increasing salinity is carried out in the Nefzaoua oases. The results flow into the international forum organized by the Observatoire du Sahara et du Sahel in Tunis, which brings together the water managers and experts from the three countries involved.

More detailed information can be found in the following poster:

• Optimal Utilization of Non-Renewable Groundwater Resources

Main publications

Besbes M, Abdous B, Abidi B, Ayed A, Bachta M, Babasy M, Ben Baccar B, El Batti D, Ben Salah Y, Charreton MB, Biout F, Douma A, Fezzani C, Gadhi M, Horriche F, Kadri S, Khadraoui A, Khanfir R, Kinzelbach W, Larbes A, Latrech D, Margat J, De Marsily G, Mamou A, El Mejerbi M, Mekrazi A, Mhiri A, Moumni L, Nanni M, Pallas P, Pizzi G, Salem A, Salem OM, Taibi R, Zammouri M, The north western Sahara aquifer system. Joint Management of a Transborder Basin, HOUILLE BLANCHE-REVUE INTERNATIONALE DE L EAU (5): 128-133 2003.

Siegfried T., W. Kinzelbach, 2003. Management of internationally shared groundwater resources in semiarid and arid regions: the Northern African Aquifer System. In: Hydrology of the Mediterranean and Semiarid Regions, Proceedings of an International Symposium, IAHS Publ. No. 278, p. 332-338.

Siegfried, T. Die Wüste wächst, in: GEGENWORTE - Zeitschrift für den Disput über Wissen, 10. Heft, Herbst 2002, Hrsg. Berlin-Brandenburgische Akademie der Wissenschaften

Contacts

W. Kinzelbach

Agency/Funding

Alliance for Global Sustainability/155 kCHF

Partners

OSS, Tunis, DGRE Tunis

Status

To be finished in 2004, with more local studies continuing in 2005