Anthropogenic Impact on the Non-closure of GRACE-based Water Budget in Hai River Basin, China

Abstract:

The budget non-closure is commonly found in GRACE-based water budget (GRACE-WB) and usually explained as measurement errors. Since GRACE has a unique ability to detect the change of water storage both due to natural and anthropogenic factors, the non-closure needs to be investigated from not only measurement errors but also anthropogenic effects. The Hai River Basin (HRB) is selected as the study area to explore the relationship between the GRACE-WB non-closure and human modifications to water, including groundwater consumption and water diversion, with a considering of the outstanding feature of GRACE. The in situ measured precipitaion (P) and net runoff (R), together with evapotranspiration (E) from GLDAS land surface models (LSMs), are used to calculate the budget error between terrestrial water storage change (ΔTWS) derived from GRACE and P-E-R. It is found that the budget errors are comparable to bulletin reported water consumption and human modifications to water (groundwater use + water diversion), at annual and inter-annual scale, respectively. It is concluded that the GRACE-WB non-closure in HRB is dominated by the difference between LSM-simulated and GRACE-monitored water storage change resulted from anthropogenic use of water, which is usually not included in most LSMs but still seen by GRACE.