Understanding source sustainability in hard rock aquifers using Gravity Recovery and Climate Experiment: A case study from Telangana, India

Abstract The rise in groundwater extraction, exacerbated by climate change, poses a significant sustainability threat, particularly in hard rock terrains with limited storage capacity. In Telangana, India, a region characterized by semi‐arid climatic conditions and dominated by crystalline hard rock aquifers across approximately 85% of its geographical area, groundwater serves as a primary water source. An analysis of terrestrial water storage (TWS) over Telangana for the period 2002–2020 reveals pronounced seasonality and significant inter‐annual variability. This inter‐annual variability closely reflects the region's rainfall patterns and anthropogenic water extraction and is linked to El Niño‐Southern Oscillation (ENSO) events. Positive TWS anomalies (TWSA) are associated with the Kharif season and the southwest monsoon, whereas negative anomalies correspond to the Rabi and summer seasons, where increased groundwater extraction for Rabi cropping is prevalent. The study identifies a strong correlation at a 2‐month time lag between rainfall and TWSA‐ ( R = 0.78) and rainfall and groundwater storage anomalies (GWSA) ( R = 0.71), with the majority of TWS changes attributable to groundwater storage, showing a strong correlation with observed water levels. The TWS data effectively capture drought events, demonstrating the utility of Gravity Recovery and Climate Experiment (GRACE) in understanding water resource sustainability in the region. These findings underscore the value of GRACE data in complementing observed datasets for informed decision‐making in water resource management.