Projected climate change impacts on water resources in northern Morocco with an ensemble of regional climate models
Résumé
The Mediterranean region is considered as a hot spot of climate change, where precipitation is
likely to decrease with the rise of temperature. These changes could have a strong effect in north Africa and
notably in Morocco where the agricultural sector is of high importance and very dependent on surface water
resources. Therefore, there is a need to quantify the possible climate change impacts on water resources of
this region. The most common approach to conduct hydrological impact studies of climate change is to run
hydrological models with climate scenarios, usually provided by climate model outputs downscaled to the
catchment of interest. In the present study an ensemble of six regional climate model (RCM) simulations
from the European project ENSEMBLES at a 25 km resolution is considered to evaluate the climate change
impacts on the inflows of the sixth largest dam located in northern Morocco. A quantile perturbation method
is used to generate future temperature and precipitation series under the emission scenario A1B. The GR4J
hydrological model is first calibrated on different climatic conditions to assess the temporal transferability of
its parameters and then run with the perturbed temperature and precipitation series. The ensemble approach
allows the projection uncertainties to be evaluated from the spread in the individual RCM simulations. All
RCM simulations project a decrease in surface water resources during the extended winter season
(November to May), from –9% to –54% depending on the model.