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The underground brackish waters in South Algeria: potential and viable resources

IWRA World Water Congress 2008 Montpellier France
1. Water availability, use and management
Author(s): Bouchekima Bachir
Bechki Djamel
Bouguettaia Hamza
Boughali Slimane
Mohamed Tayeb Meftah
Laboratoire de Développement des Energies Nouvelles et Renouvelables dans les Zones Arides Sahariennes LENREZA Université de Ouargla BP 511 30000 Ouargla Algérie *Tel : 213 73725299 Fax : 21329712627 *email : bbachir@hotmail.com

Keyword(s): Underground water- Southern Algeria –Brackish water- Solar Desalination- Water supply
Article: Poster:

AbstractAlgeria disposes of a considerable amount of underground water in the septentrional Sahara. There are two types of resources: the renewable resources, which are localised in the Hoggar-Tassili and Bechar-Tindouf valleys and the non-renewable resources, which are contained in huge reservoirs of the two sedimentary basins: the Continental Intercalary and the Complex Terminal aquifers. The Continental Intercalary aquifer occupies 600,000 km2 surface with a thickness reaching 1000 m in the northern Sahara. Its water is characterised by high temperatures which can reach 60°C and over, corrosive aspect due to the presence of H2S and CO2 and a salinity of 1–2 g/L, reaching 5 g/L in certain places. The Complex Terminal aquifer occupies 350,000 km2 surface with a depth varying between 100 and 500 m. The water is characterised by a low salinity on the edges and a relatively high salinity in the center, over 6 g/L. Studies concerning its exploitation estimate that a flowrate of 156 m3/s can be used. But such an abusive utilization would not be without a negative impact from the environmental and ecological point of view, such as the draining of low depth wells and foggaras, water quality damage and harmful water uprising to the surface. However further studies are necessary for a better understanding of these phenomena and for ensuring a safer and profitable use of this wealth. Fresh water supply represents one of the major constraints to development of such areas. The presence of brackish water of moderate salinity (2000–3000 mg/L) in some of these areas can present an economic and reliable fresh water supply, if an appropriate desalination scheme is adopted. The potential role of brackish water as a source of fresh water in South Algeria and the problems related to brackish water desalination experience are discussed. A case study for brackish water desalination using reverse osmosis (RO) scheme is presented to elucidate its feasibility as compared to other water supply options. Further, planning guidelines for brackish water desalination are presented. The purpose of our study is to bring an alternative solution of supply fresh water to the southern regions of Algeria. On the other hand, the using of solar distillers could adapted to these areas more especially as their design does not present a technical difficulties. However, their output of fresh water remains insufficient. With a view to ameliorate their yield, our study aims at improving condensation of the water vapour accumulated in the distiller by a natural or forced flow towards an independent condenser. This technique constitutes a means of reinforcement of condensation and makes it possible to improve notably the effectiveness.
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