Are Droughts Becoming More Severe or Longer in Morocco Based on the Standardized Precipitation Evapotranspiration Index for 1979–2022?

Morocco has been experiencing droughts in the last three decades. Furthermore, drought frequency and severity are expected to increase due to climate change. So, a performant drought monitoring is needed to contribute to the adaptation of more efficient measures to mitigate the opposite impacts. The monitoring of the drought is generally presented by the use of drought indices, which are based on different climatic and hydrological variables. In this study, the monthly. Standardized Precipitation Evapotranspiration Index (SPEI) data for the whole of Morocco is calculated Using ERA5 Reanalysis data relies on air temperature and precipitation. The SPEI is estimated by the time scale of 6 months depending on accumulated water balance for the six previous months. This work has two main objectives; firstly, an evaluation of ERA5 Reanalysis, to choose it as an alternative data of the ground observations using statistical metrics. Secondly, this work assesses the spatial and temporal features of drought obtained from the monthly SPEI. The results show that the drought irregularly appears in Morocco and that it is possible to distinguish drought years clearly using the SPEI. In addition, the Moroccan climate experienced a significant drying tendency with increasing spatial extent, concurrently drought events have also increased in terms of frequency, duration and intensity across Morocco examined by the comparison of the two 22-year periods 1979–2000 and 2001–2022.