| Terrestrial water storage comprises all the forms of water stored under and above the earth,which plays a key role in the global and regional water cycle.However,global climate change and human activities have profoundly affected Terrestrial Water Storage and resulted in changes in the hydrological cycle,threatening sustainable water use and agricultural production over major aquifers globally.While the Gravity Recovery and Climate Experiment(GRACE)satellites provide a global view of long-term trends in terrestrial water storage,describing and quantifying impacts of climatic change and human activities on change of water storage remain confused and awkward issues.To solve this problem,the climate-driven water storage anomalies(CWSA)and human-driven water storage Anomalies(HWSA)are estimated by combining GRACE-derived TWSA and hydrological model.And the relative contribution of climate change and human activity to TWSA based on GRACE is estimated by the improved quantitative evaluation method.(1)This study evaluates the uncertainty of multiple GRACE mascon products based on the weighted fusion model,and merges multiple GRACE products to reduce the impact of a single model on TWSA,which provides a reference for the selection of GRACE data products.In addition,the temporal and spatial distribution of TWSA in the Haihe River Basin from2003 to 2015 is analyzed by using the fusion results.The result indicates that TWSA in this region showed an obvious downward trend,with a trend of-10.47±1.01 mm/yr.For the sub-regions of the Haihe River Basin,the trend in the southern plains(-11.90±1.26 mm/yr)is significantly higher than that in the northern mountainous areas(-9.60±0.89 mm/yr),showing a spatial trend distribution characteristic of high in the south and low in the north.(2)In this study,four hydrological models(GLDAS,WGHM,W3,and PCR-GLOBWB)are evaluated using GRACE-based TWSA.The comparison indicates that GRACE-based TWSA have high correlation coefficients(0.93)with PCR-GLOBWB hydrological models.And PCR-GLOBWB is closer to that of GRACE-based TWSA in the spatial distribution.Therefore,PCR-GLOBWB is significantly better than the other three hydrological models in terms of spatial distribution,time series,and included variables,relative to other hydrological models.(3)The impact of climate change and human activities on the change of water storage is evaluated by combining GRACE-derived TWSA and PCR-GLOBWB model.The result indicates that the correlation coefficients between climatic factors(precipitation and evapotranspiration)and TWSA are 0.12 and 0.17,respectively,while strong human activities had a significant impact on water storage in the Haihe River Basin.In addition,this study provides a method to quantify the relative contributions of climate change and human activities on TWSA based on GRACE.The result mainly shows that human activities have always been dominant,and its contribution to TWSA has reached 60%～85% in the plain area of the Haihe River Basin. |
