GRACE-based analysis of groundwater sustainability in the tropics

This study uses satellite observations from the Gravity Recovery and Climate Experiment (GRACE) and the Global Land Data Assimilation System (GLDAS) to evaluate groundwater storage sustainability across Colombia. The assessment integrates drought climatology estimates, basin-scale trends, and sustainability indices, providing essential information to support long-term groundwater management strategies and strengthen climate resilience. Colombia lies in the equatorial tropics, where the hydrological regime is shaped by the complex orography of the three ranges of the Colombian Andes. This study evaluates groundwater sustainability across the five major Colombian river basins from 2003 to 2024. The findings provide a basin-level perspective on groundwater dynamics, offering insights to guide sustainable water resource management in tropical Andean regions. Groundwater sustainability is at risk in numerous regions worldwide, where overexploitation threatens both resource depletion and insufficient replenishment. In parallel, regulatory agencies often lack the necessary information for effective groundwater monitoring and management. This study constitutes the first comprehensive assessment of groundwater sustainability in Colombia, overcoming challenges related to data scarcity, complex topography, and limited in-situ monitoring infrastructure. A non-parametric analysis was applied to quantify sustainability through reliability, resiliency, and vulnerability indices. Results revealed alarmingly low values, with a nationwide maximum of only 0.25. Additionally, precipitation–GWSa correlations were analyzed to estimate response times, identify areas where this relationship is strongest, and pinpoint regions where management could be improved. • Groundwater sustainability is assessed using GRACE TWS, drought climatology, and trends. • The highest depletion is observed at overextracted regions (−3.47 and −3.15 cm/month). • Groundwater recharge follows different lags in wetlands and mountain ranges (2 to 5 months). • 53.8% of groundwater reliability is achieved nationwide arising depletion concerns in the region.