Climate-Driven Shifts in Drought Dynamics in the Balkhash–Alakol Water Management Basin Revealed by Integrated Satellite and Ground Observations

Droughts represent a major threat to water security and agricultural sustainability in the arid regions of Central Asia. The Balkhash–Alakol water management basin is particularly vulnerable due to its complex runoff formation, dependence on surface water resources, and the transboundary nature of the Ile River, the main inflow to Lake Balkhash. This study analyzes hydrometeorological data for 1950–2023 using the Standardized Precipitation Evapotranspiration Index (SPEI), Streamflow Drought Index (SDI), and Surface Water Supply Index (SWSI). Satellite-based indicators, including the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST), were used to derive the Vegetation Condition Index (VCI), Temperature Condition Index (TCI), and Vegetation Health Index (VHI) for 2002–2023. Results indicate a significant increase in drought frequency and duration since the 1990s, with SPEI values reaching −2.6 during extreme events. Satellite observations revealed widespread vegetation degradation, with drought-affected areas (VHI < 30) exceeding 60% of the basin in severe years. Strong correlations between meteorological and hydrological drought indices (r up to 0.9) highlight the importance of cumulative moisture deficits. The results indicate an increase in the region’s aridity and the manifestation of drought in climatic, hydrological, and ecosystem changes. The practical significance of this study lies in the potential to use these results to improve drought monitoring and early warning systems, assess water risks, and develop measures for adapting to climate change and making decisions regarding water resource management in the Balkash–Alakol water management basin.