A new precipitation dataset is provided since 2014 by the Global Precipitation Measurement (GPM) satellite constellation measurements combined in the Integrated Multi-satellite Retrievals for GPM (IMERG) algorithm. This recent GPM-IMERG dataset provides potentially useful precipitation data for regions with a low density of rain gauges. The main objective of this study is to evaluate the accuracy of the near real-time product (IMERG-E) compared to observed rainfall and its suitability for hydrological modeling over a mountainous watershed in Morocco, the Ghdat located upstream the city of Marrakech. Several statistical indices have been computed and a hydrological model has been driven with IMERG-E rainfall to estimate its suitability to simulate floods during the period from 2011 to 2018. The following results were obtained: (1) Compared to the rain gauge data, satellite precipitation data overestimates rainfall amounts with a relative bias of +35.61% (2) In terms of the precipitation detection capability, the IMERG-E performs better at reproducing the different precipitation statistics at the catchment scale, rather than at the pixel scale (3) The flood events can be simulated with the hydrological model using both the observed and the IMERG-E satellite precipitation data with a Nash–Sutcliffe efficiency coefficient of 0.58 and 0.71, respectively. The results of this study indicate that the GPM-IMERG-E precipitation estimates can be used for flood modeling in semi-arid regions such as Morocco and provide a valuable alternative to ground-based precipitation measurements.

Abstract Extreme climate events often have a significant and direct impact on social, economic, and environmental systems. This study is an attempt to characterize the current trends and future projections of extreme climatic indices in an arid region of Morocco on both an annual and a seasonal scale using 12 precipitation and temperature-based indices. The Mann–Kendall test was used to assess the trends, and the inverse distance weighted interpolation method was employed to analyze the spatial distribution of extreme precipitation indices. The results showed that the most extreme climate indices are spatially distributed with a clear gradient from the mountainous area toward the plains. Furthermore, the analysis indicates nonsignificant downward trends in the number of days with a rainfall amount greater than 10 or 20 mm. However, a significant negative trend in the consecutive dry days was observed at the Iloujdane and Sidi Bouathmane stations. The temperature indices have recorded statistically significant upward trends at all the stations. Finally, based on the RCP4.5 and RCP8.5 scenarios, future climate change simulations show, respectively, annual precipitation decreases of 23 and 34% and temperature increases of 1.9 and 2.8 °C, which could imply substantial losses of cereal yield in the rainfed agriculture.

This research aims at establishing an integrated modelling framework to assess the impact of climate change on water supply and demand across an arid area in the western Haouz plain in Morocco. Five general circulation models (GCMs) are used to evaluate the availability of future water resources under Representative Concentration Pathways (RCP4.5 and RCP8.5 emission scenarios). The projected crop water demand and irrigation water demand were analysed using the Aquacrop software, taking into account the impact of climate change on both reference evapotranspiration and crop cycle lengths. The future water balance is simulated by means of the Water Evaluation And Planning (WEAP) tool, including several socio-economic and land use scenarios under RCP4.5 and RCP8.5 scenarios. The results reveal an important decrease in net precipitation with an average of −36.2% and −50.5% under RCP4.5 and RCP8.5 scenarios, respectively. In terms of water balance, the ‘business as usual’ scenario would lead to an increasing unmet water demand of about +22% in the 2050 horizon and to an increased depletion of the water table that could reach 2 m/year. Changing water management and use practices remains the only solution to ensure sustainable water use and deal with the projected water scarcity.

Flood frequency analysis could be a tool to help decision-makers to size hydraulic structures. To this end, this article aims to compare two analysis methods to see how rare an extreme hydrometeorological event is, and what could be its return period. This event caused many deadly floods in southwestern Morocco. It was the result of unusual atmospheric conditions, characterized by a very low atmospheric pressure off the Moroccan coast and the passage of the jet stream further south. Assessment of frequency and return period of this extreme event is performed in a High Atlas watershed (the Ghdat Wadi) using historical floods. We took into account, on the one hand, flood peak flows and, on the other hand, flood water volumes. Statistically, both parameters are better adjusted respectively to Gamma and Log Normal distributions. However, the peak flow approach underestimates the return period of long-duration hydrographs that do not have a high peak flow, like the 2014 event. The latter is indeed better evaluated, as a rare event, by taking into account the flood water volumes. Therefore, this parameter should not be omitted in the calculation of flood probabilities for watershed management and the sizing of flood protection infrastructure.

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-IMERG-F) 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.