Water in the Gareat El Tarf basin, is affected by climatic and economic constraints; while its development is based on the agricultural sector, which creates pressure on water resources. The objective of this study is to analyse the performance of the national water plan to accompany this policy, and the impact of climate change on water resources. The methodology adopted is the application of the WEAP(Water Evaluation and the Planning)software, in order to build a model for the allocation of water resources, up to 2050. The results obtained confirm that the impact of the economic policy shows a very important deficit that exceeds 400 million m3 in 2050. To face this challenge, it is recommended to adopt an economic strategy based on the protection of water resources and adapted to the supply capacities of renewable water resources.