The Abdi-Basid Courses Institute: 09/19/25

This study investigates hydroclimatic variability over the period 1961–2021 using the Standardized Precipitation Index (SPI) across multiple temporal scales. Long-term drought dynamics are assessed through the spatial slope of SPI12 and its relationship with total precipitation, while short- to medium-term variability is explored through SPI3 heatmaps, contrasting monthly and annual patterns as well as seasonal fluctuations (JF, MAM, JJAS, and OND).

A comparative analysis between a station with missing precipitation records (and consequently incomplete SPI3 series) and the corresponding regional SPI3 signal was conducted to evaluate the robustness and representativeness of local trends.

Furthermore, correlations between SPI /SPEI (3, 6, 9, and 12 months) and vegetation-related indices — NDVI (Normalized Difference Vegetation Index), EVI (Enhanced Vegetation Index), VCI (Vegetation Condition Index), and SEDI (Standardized Evapotranspiration Deficit Index) — highlight the interactions between climatic drought and ecosystem responses. Finally, the analysis incorporates the influence of major climate teleconnections, namely ENSO (El Niño–Southern Oscillation) and the IOD (Indian Ocean Dipole, particularly during OND), to assess their role in modulating regional SPI variability.

The findings provide an integrated understanding of the links between precipitation variability, vegetation dynamics, and large-scale ocean-atmosphere drivers, with implications for drought monitoring, prediction, and sustainable water resource management.