Evolution des relations pluie-débit sur des bassins versants du Maroc

摘要

The objective of this study is the analysis of the hydrological regimes of 27 river basins in Morocco in order to assess the impact of climate change on water resources. We outline 23 units of homogeneous rainfall variability with the method of the regional vector over several nested spatial scales (micro, meso and macro), to assess the representativeness and persistence of regional signals. We observe that precipitations are correlated with the North Atlantic Oscillation West of the Atlas, especially for the heart of the rainy season. We provide evidence of a generalized rainfall reduction by an abrupt change in the time series between 1976 and 1980, except in the region between the Rif and the Mediterranean Sea, where rainfall shows a trend towards a relative increase since 1980. No trend was detected in many of the Saharan units. The discharges of most of the Moroccan rivers decrease from the early 1980s: the rupture years for discharges and monthly runoff coefficients are consistent with those of rain up to 1990. We found no relation between the dates of the construction of large dams and the rupture dates in time series of river discharges on the basins concerned. The selected stations are usually located in the upstream parts of the basins, and are not much influenced by the construction of dams. These data sets are interesting to test the impact of climate change on hydrological regimes of basins not influenced by dams, allowing study of the variability of water resources that would be available for development downstream of these stations in a context of climate change.