Spatio-temporal variability of precipitation from 1980 to 2021 within the Oum Er Rbia hydraulic basin (Morocco)

Abstract The aim of this work is to assess the spatio-temporal variability of the mean annual rainfall during the last four decades within the Oum Er Rbia hydraulic basin. The used database in this study consists with a series of rainfall data at different time scale. These data were subjected to statistical and cartographic analysis. The obtained results show that, during the period of 1980-2021, interannual variability marked the evolution of annual rainfall averages. Furthermore, this variability is characterized by alternating sequences of dry and wet seasons. From the hydrological year of 2015, a general decreasing trend of rainfall has clearly marked and observed. Rainfall patterns in the Oum Er Rbia basin are also characterized by spatial variability. Interannual averages vary considerably from one catchment to another. The upstream part of the basin receives the most amount of rainfall. By contrast, the middle of the basin is the driest. The recent drop in precipitation has had a negative impact on the basin’s territory, most notably on water resources and agriculture.