Attribution of climate and anthropogenic controls on terrestrial water storage changes in the cold and arid regions of the Indus River Basin

Study region The Indus River Basin (IRB) is a major transboundary river basin in South Asia. Study focus The study focuses on quantifying the respective roles of climatic variability and anthropogenic water use in driving terrestrial water storage anomaly (TWSA) decline using a physically informed, decomposition-based attribution framework and spatiotemporal changes in TWSA over the IRB during April 2002–August 2025 using extended GRACE/GRACE-FO data. New hydrological insights for the region Trend analysis shows intensification of TWSA decline in humid (−39.8 mm yr⁻¹), semiarid (−34.9 mm yr⁻¹), and cold (−27.4 mm yr⁻¹) regions, while comparatively weak decline in arid (−4.02 mm yr⁻¹) during 2016–2025 as compared to 2002–2015. Signed covariance decomposition identified GWSA as the dominant positive component of TWSA variability (99.9–105.2%), followed by GMB (15.7–18.6%), whereas RZSM, SWE and reconstruction error provided compensating contributions. Basin-scale analysis further shows accelerated groundwater depletion during 2016–2023 (GWS ≈ −13.9 mm yr⁻¹), accompanied by intensified anthropogenic-associated TWSA decline (≈ −16.5 mm yr⁻¹). During 2016–2023, anthropogenic-associated components accounted for the largest relative magnitude shares in arid (59%) and semiarid (67%) regions and across the basin (51%). The climate-related share was largest in the cold region (55%), whereas climate-related and anthropogenic-associated shares were comparable in the humid region (38% and 36%, respectively). These findings highlight the combined influence of human water use and hydroclimatic variability in shaping recent basin-scale water storage decline.