Improving understanding of terrestrial water storage changes over China using the high-accuracy Tongji-Grace2022 model

Nine major basins in China. To enhance understanding of water resource dynamics in China, the spatiotemporal characteristics of terrestrial water storage anomalies (TWSA), from April 2002 to December 2016, are assessed using the advanced GRACE time-variable gravity field model Tongji-Grace2022. The underlying driving factors are further identified together with meteorological data and water consumption statistics. The results indicate that Tongji-Grace2022 model exhibits superior performance compared to three state-of-the-art spherical harmonic solutions (CSR RL06, JPL RL06, GFZ RL06), characterized by reduced north-south striping noise and higher signal-to-noise ratio, thereby enabling more accurate TWSA estimations. Long-term trend analysis of TWSA in China reveals the spatiotemporal heterogeneity across the nine basins: basins in the humid climatic zone present increasing TWSA, primarily attributable to abundant precipitation; basins in other climatic zones present decreasing TWSA with varying trend magnitudes, which are driven by intensified evapotranspiration and human activities, such as agricultural irrigation and industrial development, and more extensive human activities lead to faster decreases in TWSA. Moreover, TWSA changes exhibit temporal lags behind precipitation and evapotranspiration, and the longer lag months occur in basins with complex hydrogeological environments, such as those featuring multiple aquifers or karstic landscapes. The outcomes can provide theoretical supports for formulating targeted regulation policies in different basins, and eventually achieve the sustainable water resource utilization. • The more reliable TWSA in China is derived using Tongji-Grace2022 model. • Nine basins highlight the spatiotemporal heterogeneity in TWSA distribution patterns. • Precipitation, evapotranspiration and human factors jointly restrict changes of TWSA.