Solid Water Melt Dominates the Increase of Total Groundwater Storage in the Tibetan Plateau

Understanding how groundwater storage (GWS) responds to climate change is essential for water resources management and future water availability in the Tibetan Plateau (TP). However, the dominant factor controlling long-term GWS changes remains unclear and its responses to climate change are not well understood. Here we combined multi-source datasets including in-situ measurements, satellite observations, global models, and reanalysis products to reveal that GWS increased at 5.59 ± 1.44 Gt/yr during 2003-2016 while showing spatial heterogeneities with increasing trends in northern TP and glacial regions and declining trends in central and southern TP. The accelerated transformation from solid water (glaciers, snow, and permafrost; -17.72 ± 1.53 Gt/yr) into liquid water provide more recharge to groundwater, dominating the total GWS increase. This study contributes to a better understanding of the hydrological cycle under climate change and provides key information for projecting water availability under different future scenarios in the TP.