| In providing natural resources,the ecological environment is a fundamental guarantee of human survival and the material foundation of social development,spatial environment,and basic material conditions.However,as human society continues to develop,pollution and destruction of the urban ecological environment becomes more and more severe,leading to profound impacts on human survival and societal development.Consequently,the need for ecological environment change has become more urgent.Urban agglomeration has significant significance in promoting high quality,coordinated regional development as the principal body of China’s new urbanization.The Yangtze River Delta urban agglomeration is located at the intersection of the Yangtze River Economic Belt and the "Maritime Silk Road” and plays an important role in realizing the overall situation of national modernization and the overall reform and opening up pattern.Objective and quantitative monitoring of the current state of ecological environmental quality,combined with an effective and scientific assessment of the development of ecological environmental quality,is conducive to the identification and solution of potential problems in urban ecological environments,promoting sustainable economic and social development,and achieving harmonious coexistence between humans and nature.In recent years,remote sensing science and technology have been widely applied in the field of ecology,as they can achieve rapid,objective,and quantitative evaluation of regional ecological environment quality status.In this paper,the urban agglomeration of the Yangtze River Delta is taken as the object of research,selects Landsat-5 TM satellite imagery and Landsat-8 OLI imagery from 1990 to2020 as the source of data,uses Google Earth Engine(GEE)as the platform for processing remotely sensed data,and Arc GIS 10.4 as the tool for analyzing and mapping the data.The ecological quality of the area is evaluated by the Remote Sensing Based Ecological Index(RSEI),and the driving forces of natural and human activities are analysed by the Geodetector.The main findings of the study are as follows:(1)The ecological quality of the Yangtze River Delta urban agglomeration can be quickly visualised by applying RSEI in GEE.After principal component analysis of the four indicators of humidity,greenness,heat and dryness,in the first principal component,the eigenvector values of humidity(WET)and greenness indicator(NDVI)are positive and have a positive effect on ecological quality,while the eigenvector values of heat(LST)and dryness indicator(NDBSI)are negative and harm ecological quality.The absolute value of the heatiness component(LST)is significantly higher than the rest of the components,and the heatiness component(LST)has a high influence on ecological quality in this study area.(2)Between 1990 and 2020,the urban agglomeration of the Yangtze River Delta has experienced an improvement in its ecological and environmental quality.Overall,RSEI values are high in the southern portion of the study area and townships,and low in the southeastern coastal and built up areas.With the accelerated urbanization process,the distribution of areas with low RSEI values gradually changed from "sporadic" to "continuous" areas.0.560,0.516,with an overall increasing trend.The cities with better and significantly improved ecological quality are all located in the southwestern part of Zhejiang Province.(3)The influence of vegetation cover,land use and elevation on the ecological quality of the Yangtze River Delta urban agglomeration is relatively strong,with explanatory power q of0.222,0.207 and 0.171 respectively.the ranking of the degree of influence of each driver on the RSEI is vegetation cover > land use > elevation > slope > night lighting > GDP >population density > precipitation > average annual temperature.The influence of the detection factors on the ecological environment showed a non-linear enhancement or a twofactor enhancement effect,and the interaction between the detection factors was greater than the single-factor effect. |
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