Climate change poses an escalating threat to global water resources, with semi-arid regions such as Morocco being particularly vulnerable due to high climatic variability and limited adaptive capacity. In these regions, including the Tassaoute watershed in central Morocco, data scarcity and uncertainties related to data availability and quality frequently hinder robust assessments of climate change impacts. Recent advances in data science and remote sensing offer promising alternatives to overcome these limitations. This study investigates the potential of the PERSIANN-CDR satellite-derived precipitation product for assessing climate change impacts on water resources. The capability of PERSIANN-CDR to reproduce observed precipitation patterns and associated hydrological responses is evaluated through a comparative analysis using observed precipitation data. Results indicate that PERSIANN-CDR generally underestimates peak precipitation events and total rainfall amounts compared to in situ observations. Runoff is simulated using two hydrological models: GR2M (Génie Rural 2 parameters Mensuel) and the Thornthwaite water balance method, both driven by observed meteorological data and PERSIANN-CDR precipitation. The future water availability was assessed using 5 climate models, under two scenarios: RCP4.5 and RCP8.5 for the periods 2030–2060 and 2061–2090. Results show a marked temperature increase of 2–3 °C across all models, accompanied by a general decline in precipitation ranging from −30% to −60% under RCP4.5 and −20% to −80% under RCP8.5. These climatic changes translate into substantial reductions in runoff, with stronger decreases projected under the high-emission scenario and during the dry season. Monthly analyses reveal pronounced seasonal contrasts, highlighting the increased sensitivity of low-flow periods to climate forcing. Overall, runoff is projected to decrease by 50–90%, with model and data-source differences highlighting the importance of multi-model and satellite-derived approaches in data-sparse regions. These results emphasize the utility of satellite precipitation datasets in guiding climate-adaptive water management strategies.

The Tassaoute watershed, a significant tributary of the Oum Er-Rbia basin in central Morocco, is experiencing increasing water stress due to climate variability and declining precipitation trends. This study aims to assess the impacts of recent climatic changes on water resources in the watershed using the HBV (Hydrologiska Byrâns Vattenbalansavdelning) conceptual hydrological model. Monthly meteorological and hydrological data were collected and used to calibrate and validate the HBV model, enabling simulation of runoff and the evaluation of the watershed's hydrological response to observed climate variability. The results highlight a noticeable reduction in streamflow and changes in seasonal water availability, which are closely linked to variations in rainfall and temperature patterns over recent decades. These findings underline the growing vulnerability of the Tassaoute watershed to climatic fluctuations and provide a scientific basis for improving water resource management in the region.