The Mediterranean area, a renowned climate change "hotspot," faces increasing water scarcity that poses a significant threat to its vital agricultural sector. As a contribution to the TALANOA-WATER project, a European-funded PRIMA project, this thesis aims to quantify the future evolution of agricultural water requirements and assess climate-driven impacts on crop yields in the Aude basin, a representative Mediterranean watershed in southern France. To achieve this, an enhanced R-based agronomic model based on the SIMETAW framework was developed, validated, and applied. The model simulates the daily soil water balance for key regional crops—including wine grapes, cereals, and fruit orchards—across 33 distinct pedoclimatic zones, driven by an ensemble of downscaled climate projections for the RCP 2.6, 4.5, and 8.5 scenarios.