| Abstract |
The North Sahara Aquifer System (NSAS), shared by Algeria, Libya and Tunisia has reserves of water, which are non renewable, however little and are not exploited in full. Over the past thirty years, the drilling operations by the system as a whole rose from 0.6 to 2.5billion m3/year. This farm is now facing many risks mainly increase on water salinity, the reduction of artesian by drawdown, the drying up of outlets, piezometric interference between countries sharing the system, The simulations on the model NSAS have highlighted the most vulnerable areas. They also identified new areas of potential tax at a lower injury. The results of this detailed knowledge of the basin hydrogeology are a mapping of aquifers for the realization of the mathematical model. The Sahara basin is a large entity layered sediment. The adoption of a simultaneous representation of all segments: water and semi-permeable, can reflect the linkage and hydraulic and chemical exchanges between all layers of the basin, and thus the behaviour of the medium and long term. A study conducted by the three countries with the contribution of SS0 (Sahara and Sahel Observatory), provides a rather optimistic view of the exploitation of water in the Septentrional Sahara as long as it takes into account together the observations and results model and that the account now has all the risk factors identified by the study. The North Sahara Aquifer System under the SSO. To the extent that mutual information strengthens solidarity, we can design the model of NSAS as a powerful educational tool and an instrument of dialogue and mediation goal, around which dialogue can be organized. At present, estimates of annual water extraction from this basin amount to 540 hm3 in Tunisia, 1,100 hm3 in Algeria and 250 hm3 in Libya. Tunisia holds an even bigger reserve of exploitable non-renewable groundwater than its neighbors Algeria and Libya with estimates in the order of 1,700 km3 (OSS, 2004). |