Integrated modeling of climate change impacts on water resources: The Souss basin in Morocco

Climate change has different impacts on water resources, altering hydrological cycles and exacerbating water-related challenges. Changes in precipitation patterns, including more frequent and intense droughts in semi-arid areas contribute to water scarcity and unpredictable availability. Being situated in central-western Morocco, the Souss basin (SB) is subject to high variations on many different scales and is strongly influenced not only by the variability of the climate but also by anthropogenic activities. SB is a strategic watershed that has considerable economic potential, mostly related to the agricultural sector, and has the typical assets and challenges of most Mediterranean watersheds. Allowing the best use of the limited water resources helps in planning better conservation and management strategies.  In this study, a DSS approach based on the ModSim-DSS model and recorded data about physical processes, hydraulic infrastructure features, and crop management was used to simulate the response of SB to climate change during the period 1990–2022. Observed rivers flow data were used to force the modeling framework over the study area. The results showed that the extent of climate change has had repercussions across the entire basin, particularly in terms of flow regimes and dam inflows. The simulation period witnessed a considerable decrease in the supply levels for the two most important dams in the region. Over the period between 2012 and 2019, there has been a notable reduction in water supplies for the Aoulouz dam, declining from an average of 100 Mm3 to 10 Mm3, representing a significant 52% decrease. Similarly, the ABDMNN dam experienced a substantial drop in water availability during the same period, decreasing from an average of 20 Mm3 to 3 Mm3, indicating a remarkable 89% decline. The differences among different supply sources fluctuate during the simulation period, resulting from changes in the available water inputs each year. The modelling approach used in this work helped identify the Souss basin’s potential challenges for best consideration in future sustainable water management plans.