Changes of land water storage in the Yellow River basin from 2005 to 2015

A large number of major coal energy bases of national energy strategic planning are distributed in the Yellow River basin,which occupy an important position in China′s social and economic development.In recent years,the ecological problems of the Yellow River basin have gradually attracted the attention of all sectors of society,and its fragile ecological environment has seriously restricted the social and economic development of the basin.The changes in land water reserves caused by climate change and human activities are investigated,and the errors caused by coal mining in the calculation process of land water reserve changes in the Yellow River basin are investigated. The GRACE gravity satellite data is processed using MATLAB programming to obtain the surface gravity disturbance from 2005 to 2015.Since the gravitational change of the surface is basically caused by the change of land water reserves,the gravitational disturbance is converted to the equivalent water height to express the change of land water reserves and analyze its temporal and spatial changes.The GLDAS data was used to calculate the change value of surface water reserves .In the process of treatment,the same filtering method as the GRACE gravity satellite data was adopted,and the change value of land water reserves was subtracted from the change value of surface water reserves to the change value of groundwater reserves.The precipitation data was cross-interpolated to obtain the spatial distribution of the average annual precipitation in the Yellow River basin from 2005 to 2015.The temporal and spatial changes of land water reserves in the Yellow River basin were obtained.The change trend of land water reserves in the Yellow River basin from 2005 to 2015 was -5.20 mm/a,and the change trend of land water reserves in 2005-2006 reached -0.91 mm/month,and only July-September showed a surplus state in each year.In order to significantly reflect the spatial change characteristics of the change trend of land water reserves in the Yellow River basin from 2005 to 2015,combined Theil-Sen median trend analysis and Mann-Kendall test were used and it was found that 51.2% of the regional terrestrial water reserves had decreased significantly,33.3% of the regional terrestrial water reserves had increased significantly,and the proportion of flat areas was small.The final results showed that the western part of the basin was in a surplus state,and the eastern part of the basin was in a state of loss.The coal mining data of various provinces and cities in the Yellow River basin were counted and converted into equivalent water height,and the change trend was -1.95 mm/a,and the change trend of land water reserves was -3.25 mm/a,which was more accurate after deducting the trend.Through correlation analysis,it was obtained that the change of inland water reserves and the precipitation level have a certain degree of correlation (correlation coefficient r=0.33,ρ<0.01).It can be seen that precipitation was one of the reasons affecting the change of land water reserves in the Yellow River basin,and the precipitation increased sharply in July,August and September every year,resulting in an increase in the runoff of the Yellow River,which was an important reason for the obvious temporal characteristics of the change of land water reserves in the Yellow River basin. Through the above calculation and analysis,it was proved that the influence of coal mining on the accuracy of the inversion result of traditional land water reserves could not be ignored.In addition,precipitation and groundwater changes were important factors that lead to changes in terrestrial water reserves in the upstream and downstream regions,respectively.The influence of coal mining volume was comprehensively considered,which helps to improve the accuracy of the traditional inversion method of land water reserves.

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