SUMMARY
The Souss basin is considered one of the most important Moroccan basins due mainly to its high value agricultural production, however, the intensive use of groundwater has led to a lowering of the piezometric level with an average of 2–3 m per years. This paper aims to develop a decision support system to model the water resources and their uses, assessing the balance-equilibrium resources needs and analyze the future situation of the water according to different scenarios. It is noted that the use of water is excessive especially at the level of agricultural use which results in overexploitation of the groundwater of the basin. On average groundwater abstraction exceeds recharge by an estimated 260 Mm3 annually. Using water evaluation and planning system (WEAP), we built a model for managing water demand of Souss basin .three scenario of water demand were calculated by WEAP model over the period of 43 years (2007-2050), reference scenario, higher population growth scenario and demand side management scenario. The results confirmed that the proposed approach is valid to build a decision support system for Souss water resources management.