| The ecological environment is the basic guarantee for human survival and the foundation for social development.The comprehensive,objective and scientific evaluation of ecological environment quality is the prerequisite for the coordinated development of economy and environment.Korla is a typical oasis city in Xinjiang,with special geographical location,many landforms,arid climate and fragile and sensitive ecological environment.Therefore,a full understanding of the characteristics of the changes in ecological and environmental quality in the region and a clear understanding of the driving factors of environmental change will help to improve the overall ecological environment in the region,at the same time,it can provide scientific basis for reasonable development of regional resources and Oasis Development.This paper is based on six Landsat remote sensing images in 1994,2000,2006,2011,2016 and 2021,combined with meteorological,terrain,land use and socio-economic data in the area,and supported by two software platforms:ENVI5.3 and Arc GIS10.5.The indexes of greenness(GDVI),Wetness(Wet),heat(LST),dryness(NDBSI),sand desertification(DI)and salinity(MSI)were extracted to construct a Multi-index remote sensing ecological index(MRSEI)model was used to comprehensively evaluate the changes of eco-environmental quality in Korla region from1994 to 2021 and analyze the causes.The conclusions were as follows:(1)After normalization,the mean changes of the six evaluation indexes are as follows:GDVI and Wet have roughly the same trend of change,showing an overall upward trend;NDBSI and DI showed a downward trend,which played a positive role in ecological environment balance.The mean fluctuation of LST and MSI increased,which had a negative effect on ecological environment balance.(2)The constructed MRSEI index can comprehensively reflect the ecological environment of Korla region.Its mean value fluctuates between 0.29 and 0.38,and the mean values of each period are 0.335,0.295,0.331,0.374,0.352 and 0.360,respectively.It shows an overall upward trend,indicating that in the past 27 years,The ecological and environmental quality of Korla has been improved.(3)The spatial distribution of eco-environmental quality in Korla is obviously different.The eco-environmental quality in Korla is mainly poor or poor,which is mainly distributed in the desert area,salinized area and ancient river area in the west of the study area,and the low mountain area and alluvial sector in the north of the study area.The areas with average,good and excellent grades were mainly distributed in the oasis area,high mountain area and middle mountain area in the southeast of the study area.From the perspective of change trend,the proportion of areas with poor grades increased from 1994to 2000,and then showed a general downward trend.The area proportion of poor and general grades showed a decreasing trend,while the area proportion of good and excellent grades showed an increasing trend.(4)From 1994 to 2021,the areas of improved,unchanged and degraded ecological environment quality in Korla region were 1582.299km~2,3637.634km~2and 2153.597km~2,respectively.In the five research stages,the proportion of the area of the degraded area showed a downward trend as a whole,while the proportion of the area of the improved and unchanged area showed an upward trend as a whole.(5)The correlation between evaporation and ecological environment quality was the highest among the meteorological elements,and the correlation coefficient was 0.857.With the increase of elevation and slope,the overall ecological environment quality is gradually getting better.When the land use types were water area,cultivated land,forest land and grassland,the ecological environment quality was better,but the unused land,glacier land and construction land was poor.Among the socioeconomic factors,the total population at the end of the year has the highest correlation with eco-environmental quality,with a correlation of 0.983. |
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