Spatiotemporal Analysis of Drought Trends in Sicily Using ERA5-Land Data  

Drought presents significant impacts on water resources, agriculture, and socioeconomic stability, particularly in the Mediterranean region, where climate change intensifies these challenges. This study examines the long-term spatiotemporal trends of drought in Sicily using ERA5-Land reanalysis data from 1950. The Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) at 1-, 3-, 6-, 12-, 24-, and 48-month scales were employed to quantify drought conditions across multiple timescales. To detect and quantify trends while accounting for autocorrelation, the Modified Mann-Kendall test and Sen’s slope estimator were applied. Results confirmed that 2002 was the most severe drought year, affecting all timescales. Spatial analysis indicated that western, southern, and southeastern regions, including Trapani, Catania, Syracuse, and Ragusa, experienced the highest severity and frequency of drought events. Conversely, northeastern areas, such as Messina and parts of Palermo, were less affected. SPI exhibited increasing trends in the eastern part of Sicily (Province of Catania); whereas SPEI trends indicated significant drying in western regions. Severe drought episodes (SPI/SPEI ≤ -1.5) were evenly distributed across short-term scales (1- and 3-month scales) but exhibited spatial variability at longer timescales (24- and 48-month scales). Extreme drought episodes (SPI/SPEI ≤ -2) were concentrated in western and northwestern Sicily, with SPI detecting up to 40 extreme events and SPEI identifying up to 25. These findings highlight the critical need for targeted, adaptive strategies to mitigate drought impacts, particularly in western and southern Sicily. Even though ERA5-Land precipitation and temperature data present some limitations, the analysis revealed that they are suitable for identifying the most severe drought episodes, especially at longer aggregation timescales (12 and 24 months). The study thus underscores the importance of continuous drought monitoring and advanced modeling techniques to inform mitigation and adaptation efforts.