Evolution And Driving Force Analysis Of Ecological Environment Quality Based On MODIS Data In The Yellow River Basin

The Yellow River Basin is an important birthplace of Chinese civilization,and its ecological environment is an important part of China’s ecological civilization construction.Analysis of the evolution trend of its ecological environment quality and the influence of different driving factors is of great significance to the ecological protection and high-quality development of the Yellow River Basin.Based on the remote sensing cloud computing platform Google Earth Engine,this study uses MODIS remote sensing surface reflectance data,vegetation index data and surface temperature data to construct a remote sensing ecological index of the Yellow River Basin by principal component analysis.We used various research methods such as ecological index classification and difference analysis,standard deviation ellipse,Theil-Sen slope estimation,Mann-Kendall test,coefficient of variation and Husrt index to analyze the temporal and spatial characteristics of the ecological environment quality in the Yellow River Basin from 2000 to 2020.In addition,the Geodetector model was used to quantitatively explore the driving factors affecting the spatial distribution pattern of the ecological environment quality in the basin.The main conclusions of the study are as follows:(1)The spatial distribution of ecological environment quality in the Yellow River Basin varies significantly,and the overall spatial distribution pattern is “excellent in the south and poor in the north”.The ecologically excellent areas are mainly located in the southern and western parts of the basin.The areas with excellent ecological environment quality are mainly located in the Qinling Mountains,Zhongtiao Mountains,Ziwuling and Luliang Mountains in the southern part of the basin,and the areas with good ecological environment quality are mainly located in the Qinghai-Tibet Plateau and Qilian Mountains.The ecologically fragile areas are mainly concentrated in the Kubuqi Desert,the Mu Us Sandy Land in the northern part and the Gonghe Basin in the northwest of the Yellow River Basin.(2)There is a phenomenon of coexistence of improvement and degradation in the ecological environment of the Yellow River Basin.Generally speaking,the improved area is larger than the degraded area.The areas of improved ecological environment quality are mainly located in the central and northern areas of the basin,such as the Hetao Plain,the Northern Shaanxi Plateau,the Liupanshan Nature Reserve,the Mu Us Sandy Land and the Luliang Mountains.The areas with degraded ecological environment quality are mainly located in large and medium-sized cities and surrounding areas with relatively dense population distribution,such as Xi’an,Luoyang,Zhengzhou,Tai’an and Yinchuan.The center of gravity of the regions with the best ecological quality grade in the Yellow River Basin gradually shifted to the northeast,and the centers of gravity of other grades were relatively concentrated.(3)The ecological environment quality of the Yellow River Basin is jointly affected by a variety of driving factors,and the driving effects of different factors in the upper,middle and lower reaches of the basin are significantly different.The q value of the annual precipitation factor is the largest,followed by the soil type and landform type factor,indicating that natural factors are the main factors affecting the spatial distribution pattern of the ecological environment quality in the Yellow River Basin.The ecological environment quality of the upper,middle and lower reaches of the Yellow River is affected to different degrees by human factors,and the influence of land use type factors in the middle and lower reaches of the Yellow River is significantly higher than that in the upper reaches.The interactions between different driving factors all showed synergistic effects,which were manifested as two-factor enhancement and nonlinear enhancement,and there was no independent or weakened phenomenon.The factor combination with the highest interaction strength is annual precipitation and land use type,followed by annual precipitation and population density.