Estimation and condition of groundwater recharge in semiarid zone: example from the Ksour Ridge, NW Algeria

In a recharge area characterized by a semiarid or arid climate and a low annual rainfall, aquifers can be hardly recharged adequately, as it was demonstrated by classical monthly hydrological balance computations. The methodology proposed in this work relies on spatial and temporal interpolation of scarce climatic data. This methodology can be used to determine the recharge flow of aquifers in these zones. The AinSefra’s syncline (Western Saharan Atlas, Southwest Algeria) includes the sandstone aquifers of Continental Intercalary and the Plio-Quaternary layers. It forms an excellent example for this application. Three years with different annual rainfalls are chosen in this application: 1983 as dry year, 2006 as average year, and 2008 as humid one. This application requires information about the soil nature, the surface, and the altitude of the recharge areas. The rainfall and the recharge flow of aquifers indicate that the principal recharge areas are the Jurassic outcrops in the humid years when the annual rainfall exceeds 300 mm.