Spatiotemporal analysis of soil moisture drought in the Horn of Africa

Droughts continuously threaten human life, livestock, and agriculture across the Horn of Africa (HOA). As climate change exacerbates drought frequency and severity, accurately quantifying spatiotemporal drought patterns is critical to developing evidence-based policies that mitigate impacts and build resilience among vulnerable communities. This study conducted a spatiotemporal analysis of soil moisture drought over the HOA, utilizing high-resolution ERA5 reanalysis data between 1951 and 2020. The Standardized Precipitation Evapotranspiration Index (SPEI) was calculated at 3-, 6-, 9-, and 12-month timescales to identify historical drought events and assess drought duration and intensity changes over 70 years. Spatial analysis revealed decreasing soil moisture levels across HOA, with the most substantial reductions of 45% occurring in Djibouti and Northern Somalia. Comparisons between the baseline period (1951-1985) and the recent period (1986-2020) showed increasingly negative SPEI intensities, indicating a shift towards drier conditions, especially in Somalia, Kenya, and Ethiopia. The results also pointed to rising frequencies of moderate droughts by around 15% and severe droughts by 5-10% from 1986 to 2020 in the baseline period. The findings can inform policy to improve regional drought monitoring systems and the development of climate-resilient agriculture strategies, water resource management, and disaster risk reduction planning to protect lives and food security.