Presentation of the agency

Due to the aridity of the climate, the watersheds of the Sahara have very limited surface runoff. Groundwater constitutes the main mobilizable water resources, although largely of a fossil and non-renewable nature. Surface waters In terms of surface water, the most important hydrological basin is that of Sakia El Hamra, which covers an area of 81,000 km². The rest consists of poorly individualized diffuse networks, due to the almost horizontal topography, infrequent precipitation, and high evaporation. The important features that characterize the flows are: – The very low number of days of flow in the year, caused by the scarcity of precipitation. – The strong floods during significant rainy episodes. – The weak parts (in terms of basin area) are active, contributing to the flows. Groundwater The hydrogeology of the region is characterized by the presence of two distinct aquifer domains: the sedimentary domain, which includes the majority of the region’s groundwater, and the crystalline basement domain, which can contain limited but highly valuable water flows for supplying water to the area. Crystalline basement domain. : This domain is composed of rocks of Precambrian or Paleozoic age that occupy the eastern, southeastern, and northern zones of the basin. It lacks widespread aquifers and water circulation is limited to fracture zones and riverbeds. Water is generally encountered at shallow depths with low flow rates and is of good to moderate quality. The regions affected by this context are located in the provinces of Es Smara (Haouza, Jdiria, and Amgala), Boujdour (Gueltat Zemmour), and Aousserd (Aousserd and Tichla). Sedimentary basin domain (Laayoune-Dakhla). : This domain occupies the western part of the basin, along the Atlantic Ocean. It covers an area of approximately 110,000 km² on land and continues underwater. It is relatively rich in widespread underground water reservoirs. The scarcity of precipitation means that the aquifers are poorly or not recharged. Isotopic analyses confirm that the majority of groundwater infiltrated more than 5,000 years ago and, therefore, these are considered fossil aquifers.