GPM-IMERG product: a new way to assess the climate change impact on water resources in a Moroccan semi-arid basin

Due to the lack of observed data, climate change impact studies are difficult to conduct. This paper evaluates the effect of climate change on water resources, in a Moroccan basin, using the Final Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM-IMERGF) for precipitation and the European Reanalysis fifth generation (ERA5) for evapotranspiration. The two-parameter monthly model of Rural Engineering (GR2M) is calibrated and validated using ground-based and GPM precipitation products, observed and ERA5 temperature and uncorrected and corrected discharge using water intake data. Five regional climate models are used to assess the future changes during the period 2025-2060. The results show that the hydrological model is able to simulate the monthly surface runoff. The same results are obtained using satellite precipitation data and ERA5 reanalysis product which remain, respectively, a source of precipitation and temperature data in case of ungauged or poorly gauged watersheds. The assessment of the climate change impact shows an increase in temperature accompanied by a decrease in precipitation. These changes would lead to a decrease in surface runoff ranging from -1 to -45% based on observed and GPM-IMERG precipitation data. This study presents an alternative source of precipitation for evaluating the climate change impact on water resources.