Hydroclimatic Variability across Minor Krishna River Basin, India: Insights from Soil–Climatic Water Balance and Drought Assessment

This study estimates soil-climatic water balance components and evaluates significance of Thornthwaite method-based actual evapotranspiration (AET) using SWAT simulations and satellite data while assessing spatio-temporal water balance variability (2000-2023) across the Minor Krishna River Basin, India. SWAT model performed well at the discharge stations (mean R2 = 0.70, NSE = 0.66). Humid zones exhibited adequate water availability, while dry sub-humid regions faced persistent deficits, and semi-arid conditions showed lowest surplus. Seasonal water-balance dynamics reflected the interplay of rainfall, soil-water storage, and evapotranspiration (ET) demand, driving surplus–deficit transitions. Drought classification captured varying severity and intensity of hydroclimatic stress across basin. Lead-lag analysis between Precipitation (P) and Thornthwaite-based AET anomalies and Terrestrial Water Storage Anomaly (TWSA) from Gravity Recovery and Climate Experiment (GRACE) revealed a maximum correlation (R = 0.65) at 3-month lag, indicating basin’s hydrologic memory. The findings underscore climatic influences on regional hydrology and emphasize for sustainable water management.