A Study On Influencing Factors And Drought Conditions Of Water Storage Change In The Yellow River Basin

Changes in terrestrial water stocks are a key component of the terrestrial hydrological cycle,Using changes in terrestrial water storage allows the balance between hydrological inputs and outputs to be determined for the entire study area,It also enables direct monitoring of water resource changes at the basin scale.The rate of human exploitation of surface and groundwater has been increasing in recent years,Continued global temperature rise and accelerated rate of vegetation change,These factors have led to dramatic fluctuations in terrestrial water reserves,Changing the global spatial distribution of water resources and total water resources.Quantifying changes in terrestrial water reserves is important to accurately quantify changes in terrestrial water reserves,It can determine the hydrological cycle of a watershed in response to human activities and climate variability,It is of great importance for improving water resources management,preventing droughts and floods and rationalising agricultural production.This paper takes the Yellow River Basin as the subject of study,Based on GRACE gravity satellite CSR RL06 Mascon data,Combining monthly values of precipitation data monitored by the National Centre for Meteorological Science and Technology meteorological sites,MODIS13A2 month-by-month vegetation cover data,SPEI drought index and human activity data for the Yellow River basin.Firstly,Estimation and analysis of spatial and temporal variation of terrestrial water reserves in the Yellow River Basin from 2003-2018,Quantifying the impact of climate variability,vegetation cover and human activities on changes in water storage in the Yellow River Basin.Revealing the influence of different factors on water storage changes in the Yellow River Basin and their spatial distribution patterns.Finally,Building a drought index based on data on water storage changes monitored by the GRACE gravity satellite,Reflecting the process and intensity of extreme weather events in terms of the terrestrial water cycle,A more comprehensive picture of the drought in the Yellow River Basin.The main work and findings of this paper are as follows:(1)Changes in water storage in the Yellow River basin decreased sharply at a rate of0.5639mm/year between 2003 and 2018,The largest positive anomaly occurred in 2003 at approximately+2.8mm and the smallest negative anomaly occurred in 2016 at approximately-7.16mm.From the spatial point of view,Significant spatial heterogeneity in the characteristics of water storage changes in the Yellow River Basin,The areas of significant increase in water storage changes within the Yellow River Basin are mainly concentrated in the source areas of the Yellow River in the upper reaches of the Yellow River Basin,Maximum change of+10mm/year;The areas showing significant declines are concentrated in the middle and lower reaches of the Yellow River Basin,mainly in the provinces of Shanxi,Shandong,Shaanxi and Henan,Maximum change of-40mm/year.The Yellow River Basin has a distinct seasonal cycle,with water reserves decreasing during most of the autumn and winter and increasing throughout the rest of the year.(2)Changes in water storage are influenced by a combination of climate change,human activity and changes in vegetation cover.In this study,precipitation,drought index,vegetation cover and human abstraction were selected as influencing factors to study the effect of different factors on water storage changes.SPEI can effectively reflect the dry and wet conditions and energy exchange processes in the basin,and the higher SPEI is related to the change of water storage in the Yellow River basin,The correlation coefficient is r=0.70;There is a significant positive correlation between precipitation and changes in water storage in the Yellow River basin,The correlation coefficient is r=0.68;Significant negative correlation between vegetation cover and changes in water storage in the Yellow River basin,The correlation coefficient is r=-0.69;Extensive revegetation of the Yellow River Basin has led to a decline in groundwater reserves.Human abstraction has the greatest impact on changes in water storage,with a significant negative correlation between the two,The correlation coefficient is r=-0.78.Human activities are the main reason for the decreasing water reserves in the Yellow River basin in recent years.(3)Construction of a drought index GRACE-DSI using water storage variability data from the GRACE gravity satellite.The standardised drought index GRACE-DSI time series were calculated for the years 2003 to 2018,and compare it with the SPEI at each time scale in terms of time series and spatial distribution,The GRACE-DSI drought index was found to be the most consistent with SPEI06 when compared.Indicates that GRACE-DSI can monitor the long-term accumulation of water scarcity.Finally,the drought monitoring results of GRACEDSI in the Yellow River Basin provinces in 2016 were validated.The results show:26 recorded drought events in the Yellow River Basin in 2016,23 drought events monitored using GRACE-DSI,Monitoring accuracy of 88.5%,It shows that the GRACE-DSI index can determine the duration of drought events,quantify the intensity of drought,and can independently monitor changes in wet and dry conditions in the Yellow River basin.