Exploring potential drivers of terrestrial water storage anomaly trends in the Yangtze River Basin (2002–2019)

Study region: Yangtze River Basin (YRB). Study focus: While water storage changes in the YRB exhibit noticeable trends, their potential drivers remain largely unexplored. This study aims to explore drivers of terrestrial water storage anomaly (TWSA) trends derived from the Gravity Recovery and Climate Experiment (GRACE) and its Follow-On (GRACE-FO) missions within the YRB. Linear regression and Independent Component Analysis (ICA) are employed to assess trends in TWSA and identify statistically independent TWSA patterns over sub-regions. Subsequently, surface water storage anomaly (SWSA) and groundwater storage anomaly (GWSA) are decomposed from TWSA to facilitate the exploration. New hydrological insights for the region: Our results find five spatially independent TWSA trend clusters. Significant increasing trends in TWSA within the source region are attributed to increases in SWSA and GWSA due to glacier melt and permafrost thawing, respectively. In western Sichuan Province, the decline in TWSA is due to decreases in GWSA, probably resulting from groundwater consumption in southwest China. The most significant increasing trends in TWSA are observed in the central region. Increased precipitation and reservoir filling in this region lead to the rising SWSA, whereas the unique topography partially contributes to increases in GWSA. In the coastal area, precipitation is the primary driver, where TWSA displays non-significant increasing trends. Our findings also indicate that the Three Gorge Reservoir dominates the observed TWSA increases in Hubei Province, while Lake Poyang accounts for about 30% of the increasing TWSA trend observed in Jiangxi Province.