Study On The Evolution And Driving Force Of Surface Ecological Environment In Western Lli Basin Based On NDVI

The western region of lli Basin is the key area of China's "The Belt and Road" strategic project,which is located in the northwest interior and has a typical fragile ecological environment in arid and semi-arid areas.At the same time of the rapid development of local economy,the ecological environment has been damaged,such as soil salinization,grassland degradation,water reduction and other ecological degradation phenomena have appeared,seriously threatening the development of regional ecological-economic integration.Therefore,the study of ecological environment evolution is carried out in time to provide important theoretical support for the coordinated development of ecological civilization and social economy.Based on RS and GIS technology and LUCC theory,this paper systematically studies the evolution of the surface ecological environment in the western region of lli Basin,and quantitatively analyzes the drivers and the degree of influence of the evolution of ecological environment.The main findings are as follows:(1)Using land-based satellite remote sensing data,the land use/cover change in lli Basin was quantified,and the spatial and temporal evolution characteristics of land use/cover change in the study area in the past 40 years,under the combined action of natural factors and human activities: grassland as the main body of land use type in the study area,its area is in the study period.Internally,according to the analysis of land use transfer matrix,the reduced grassland is mainly converted into cultivated land,forest land and waters,and the salt-alkali land,marshland and sand land in the study area have increased to varying degrees,but the increase is decreasing,indicating that the overall ecological environment of the study area has stabilized.(2)Based on GIMMS-NDVI and MODIS-NDVI data,using Arcgis software platform,using the maximum synthesis method(MVC)and time series data reconstruction technology,the long-term sequence vegetation index data of different scales in the study area is obtained.At the same time,the GIS spatial analysis method combined with the mathematical means of standard deviation,mean and unitary linear regression analysis was used to study the change of surface vegetation cover in The Ili Basin and its western region sit at different time-space scales,and the main conclusions are:(1)The overall NDVI mean of The Ili Basin is about 0.653,the overall vegetation coverage is high,and there is a clear spatial difference of the opposite sex.In terms of time,the annual change of vegetation cover was-0.003/10 a,indicating a slight decline in vegetation cover;(2)The western part of lli Basin is based on desert and the main ecology is arid and semi-arid.The overall vegetation cover in the study area from 2001 to 2018 was increasing,with the average change of NDVI in the growth season being 0.034/10 a,the areas with reduced vegetation cover were mainly concentrated in the sparse vegetation areas such as Gobi and desert in the low-to-medium mountain areas and the marginal areas of the water body,and the areas with increased vegetation were mainly concentrated in agricultural vegetation areas with more frequent human activities.(3)Based on the topographic geomorphological data,meteorological data,groundwater level buried data and groundwater mineralization data,population and economic development and other non-remote sensing data in the western region of lli Basin,combined with mathematical statistical analysis and GIS spatial analysis methods,quantitative research was made on the driving force of vegetation cover change in the western region of lli Basin,and the natural factors were found to be the absolute driving force of the evolution of the surface ecological environment in the study area.The vegetation cover and its changes in the study area have obvious distribution law in the upward trend: the topographical features basically control the basic spatial pattern of vegetation cover in the study area,and the natural and socio-economic factors such as temperature,precipitation,groundwater depth and mineralization are the main drivers of the change of surface ecological environment.The vegetation cover of the area above 700 m above sea level in the study area is mainly influenced by the independent influence of natural factors,and the area below 700 m is affected by the combination of temperature,precipitation,groundwater depth and mineralization,population and economy.