John Libbey Eurotext

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Changes in big dams of arid areas: Some examples in Algeria Volume 20, issue 1, janvier-février-mars 2009

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Département des sciences de l’eau et de l’environnement Faculté des sciences de l’ingénieur Université Saad-Dahlab-Blida Route de Soumaa BP 270, Blida Algérie, IRD, UMR G-EAU 361, rue J.-F.-Breton BP 5095 34196 Montpellier cedex 05 France, Laboratoire de recherche eau, roche, et plante

The rapidly growing water demand in the Maghreb countries is forcing national authorities to build more and more dams in order to increase the available water resources, which are naturally limited, and to face the strong temporal irregularity of rainfall (seasonal and interannual). Algeria presently has 57 big dams with a total capacity of 6.8 Gm 3. Still, this potential quantity of water is lowered by the silting-up of reservoirs, evaporation from the lakes and water losses through bank and dam foundations. According to the last measurements in 2006, the silting-up of the 57 Algerian big dams is 45 Mm 3/yr, with strong disparities from one site to another and a significant increase in erosion in some catchments during the last decades. This situation represents a decrease in capacity of 0.65% per year. Evaporation measured at 39 big dams causes a mean annual loss of 250 Mm 3, i.e. 6.5% of their maximum capacity. Uncontrolled water losses through banks and foundations were estimated at 40 Mm 3/yr for 22 big dams.