Analysis Of Water Storage Variation In Shiyang River Basin By The GRACE

Shiyang river basin is one of the typical inland river basins in the northwest China.Because of high level of exploitation,the consumption of water resources is far rather than the total amount of water resources,and the continuous excessive over-exploitation of groundwater has caused a series of ecological and environmental problems.Since the implementation of key governance measures in 2008,the ecological environment of the river basin has been effectively improved.It is great significance to monitor and research the variations of water resources for the sustainable and healthy development in river basin.The traditional monitoring storage of water is mainly rely on water monitoring wells,and the monitoring stations are unevenly distributed and limited number.But the time-varying gravity field of GRACE can resolve the defect of low space-time resolution at the scale of region,which provides a new method for researching the terrestrial water storage variations in Shiyang river basin.This paper elaborated the theory and data processing methods of GRACE gravity satellite and its invert the variation of terrestrial water storage,the data of GRACE gravity satellite 2003~2015 year are using to invert the variations of terrestrial water storage in Shiyang river basin,and analyzing the variations of terrestrial water storage combine with the data of GLDAS hydrological model and precipitation.Then the groundwater reserve variations are balanced calculate by subtracting the GLDAS of surface soil water and snow water equivalent from the GRACE,and combined with groundwater level data and water resource bulletin data to analyze the variations of water storage.The results of GRACE inversion of terrestrial water storage show that: in terms of time,the terrestrial water storage in the Shiyang River Basin show an upward trend of 0.95mm/a and obvious seasonal changes;In terms of space,there is a relatively obvious ladder shape from the southwest to the northeast,the southern mountainous areas and the northern hilly areas present consistent changes,the middle and downstream basins present consistent changes,and the losses or surpluses stations are consistent.Comparing with the GLDAS hydrology models,both of them are obvious seasonal changes,the fluctuation rule has a good consistency and the strong correlation is 0.80 in the annual changes;comparing with the precipitation data,the strong correlation is 0.64 in the seasonal changes,and the terrestrial water storage correspondingly increase with the precipitation,but the peak of the terrestrial water storage changes slightly behind the precipitation by about 1-2 months.The groundwater storage results obtained by GRACE inversion show that there are obvious seasonal fluctuations and declining trend with the groundwater of level data,and the correlation coefficient is 0.79,both the inversion of groundwater storage and the level groundwater present downward trend before 2008,and upward trend after 2008,but the rate of change with a large difference;the seasonal correlation coefficient with precipitation is 0.72;with the comparison of groundwater extraction and the cross-basin water transfer found that increasing the cross-basin water transfers and causing rise of the level groundwater by reducing the exploitation of groundwater in a certain extent.