Satellite-based estimates of groundwater depletion in India (2009) reveal that groundwater in Rajasthan, Punjab, and Haryana is being depleted at a mean rate of 4.0 ± 1.0 cm yr⁻¹, equivalent to 17.7 ± 4.5 km³ yr⁻¹. This depletion, observed between 2002 and 2008, equates to a net loss of 109 km³ of water, double the capacity of India's largest surface-water reservoir. Annual rainfall was near normal, and other terrestrial water storage components did not significantly contribute to the decline. Groundwater depletion is attributed to unsustainable irrigation and anthropogenic use. If no action is taken, it could lead to reduced agricultural output and water shortages, causing socioeconomic stress. Groundwater responds slowly to meteorological changes, with residence times ranging from months to millions of years. In arid regions, withdrawals often exceed recharge. Despite increasing water pressure, groundwater laws have not evolved. Groundwater depletion is not limited to dry climates; pollution and mismanagement can lead to over-reliance on groundwater in regions with abundant rainfall. India faces severe water shortages, with groundwater accounting for 50–80% of domestic use and 45–50% of irrigation. The Indian government established the Central Ground Water Authority in 1986 but faces challenges in implementing coordinated management due to overlapping political and aquifer boundaries. The Gravity Recovery and Climate Experiment (GRACE) satellite measures terrestrial water storage (TWS), including groundwater. By isolating groundwater storage from TWS data using auxiliary information, researchers found a groundwater depletion trend of 4.0 ± 1.0 cm yr⁻¹. The study highlights the urgent need for sustainable groundwater management to prevent severe consequences for the region's 114 million residents. The methods involved using GRACE gravity solutions, filtering noise, and isolating groundwater storage from TWS data. The results indicate that groundwater depletion is primarily due to human consumption rather than natural variability. The study underscores the importance of addressing groundwater overuse to ensure long-term water security.Satellite-based estimates of groundwater depletion in India (2009) reveal that groundwater in Rajasthan, Punjab, and Haryana is being depleted at a mean rate of 4.0 ± 1.0 cm yr⁻¹, equivalent to 17.7 ± 4.5 km³ yr⁻¹. This depletion, observed between 2002 and 2008, equates to a net loss of 109 km³ of water, double the capacity of India's largest surface-water reservoir. Annual rainfall was near normal, and other terrestrial water storage components did not significantly contribute to the decline. Groundwater depletion is attributed to unsustainable irrigation and anthropogenic use. If no action is taken, it could lead to reduced agricultural output and water shortages, causing socioeconomic stress. Groundwater responds slowly to meteorological changes, with residence times ranging from months to millions of years. In arid regions, withdrawals often exceed recharge. Despite increasing water pressure, groundwater laws have not evolved. Groundwater depletion is not limited to dry climates; pollution and mismanagement can lead to over-reliance on groundwater in regions with abundant rainfall. India faces severe water shortages, with groundwater accounting for 50–80% of domestic use and 45–50% of irrigation. The Indian government established the Central Ground Water Authority in 1986 but faces challenges in implementing coordinated management due to overlapping political and aquifer boundaries. The Gravity Recovery and Climate Experiment (GRACE) satellite measures terrestrial water storage (TWS), including groundwater. By isolating groundwater storage from TWS data using auxiliary information, researchers found a groundwater depletion trend of 4.0 ± 1.0 cm yr⁻¹. The study highlights the urgent need for sustainable groundwater management to prevent severe consequences for the region's 114 million residents. The methods involved using GRACE gravity solutions, filtering noise, and isolating groundwater storage from TWS data. The results indicate that groundwater depletion is primarily due to human consumption rather than natural variability. The study underscores the importance of addressing groundwater overuse to ensure long-term water security.