Study On The Change Of Water Reserves In Shaanxi Province Based On GRACE Satellite Data

Shaanxi Province is a northern region where water resources are scarce.The per capita water resources are about half of the national per capita.The precipitation in the region is unevenly distributed during the year,with significant differences.The intensification of urbanization makes the contradiction between supply and demand of water resources,and has a great impact on the sustainability of economic development and the balance of natural ecology.It is of great significance to carry out monitoring and research on water resources change.Most of the traditional methods of monitoring water reserves are achieved by obtaining dynamic monitoring network information of surface water resources and designing corresponding monitoring systems,but they will be affected by the distribution and number of monitoring sites.Using GRACE(Gravity Recovery and Climate Experiment)satellite time-varying gravity field to invert the surface water reserves can make up for the shortcomings of traditional methods,and the inversion of surface water reserves has become a hot spot in the research and application of current gravity satellite data.Temporal and spatial analysis of large-scale regions can be an advantage by monitoring changes in the Earth's gravitational field.This paper first introduces GRACE satellite data and inversion of terrestrial water reserves theory,and then compares the strip error existing in GRACE gravity satellite data,and uses several filtering methods to process GRACE RL05 model gravity data under different filter radii and compare the effects.The analysis shows that the combination of filtering and data processing can have better strip error effects when retaining the effective signal.This paper selects Shaanxi Province as the research area,and combines precipitation and temperature data with GRACE gravity satellite data and GLDAS(Global Land Data Assimilation System)hydrological model to analyze and analyze the temporal and spatial changes of terrestrial water reserves,surface water reserves and groundwater reserves in Shaanxi Province.The time series changes show that there is a clear trend consistency between the water reserves and the precipitation changes on the monthly and seasonal time scales.The abnormal values appearing in comparison with the precipitation changes,combined with the current hydrological data,can be inferred to the meteorological disasters in the corresponding time period.Variety.However,affected by other factors such as population size and economic development,the interannual trend is weak.According to the principle of water balance equation,the difference between inland water and surface water reserves is calculated as the change of groundwater reserves and verified by the measured groundwater level in the yearbook.The data shows strong correlation.From 2004 to 2015,the annual rate of decline in terrestrial water reserves and groundwater reserves in Shaanxi Province was about 12.6 mm and 17.3 mm,respectively.The spatial changes show that the water reserves in Shaanxi Province are affected by topography and meteorological factors,and the distribution is uneven.The water reserves in various regions show their own cyclical changes.Shaanxi Province generally has a profit and loss according to the change of precipitation.In December and January to May,the water reserves in the southern region are more abundant than in the northern region;from June to November,the water reserves in the northern region are larger than those in the southern region.In addition to the trend analysis of water reserves and precipitation and temperature changes inversion by GRACE,quantitative analysis is also carried out considering a number of factors related to changes in water reserves,and water resources carrying capacity is used as a measure to evaluate changes in annual water storage utilization.Using principal component analysis to analyze the water resources carrying capacity of Shaanxi Province,it shows that the first principal component represented by population quantity and economic development exerts pressure on water resources carrying capacity;the second principal component represented by the change of water reserves is water.The resource carrying capacity is positively correlated;the third principal component represented by water resource utilization rate and the interannual groundwater level data of Shaanxi Province are standardized by data,and the correlation between the two is strong,which can be used as a reference index for judging the change of groundwater level.The government has certain reference significance in formulating water resources management regulations and controlling the scale of development and utilization of groundwater resources.