Influences of reservoir operation on terrestrial water storage changes detected by GRACE in the Yellow River basin

The implementation of water–sediment regulation scheme (WSRS) in the Yellow River can induce instantaneous water redistribution over regions through frequent reservoir operation. In this study, we attempt to detect the signal of changes in terrestrial water storage (TWS) induced by reservoir operation during WSRS based on GRACE data. Meanwhile, a modified index is proposed to further assess the contributions of human activities and climatic variability to annual changes in TWS. The results indicated that the impounding or releasing events in the XLD reservoir and the LYX reservoir during WSRS can be well detected by monthly GRACE CSR solutions with the DDK3 filter. In addition, there exists a significant correlation between annual changes in TWS and reservoir water storage changes within both the catchment area above the LYX reservoir (rs = 0.88, p < 0.01) and the catchment area above the XLD reservoir (rs = 0.86, p < 0.01). The modified index proposed in this study, which is an attribution index based on a variation analysis, showed that reservoir operation contributes significantly to changes in TWS especially for heavily reservoir-regulated regions.