Analysis Of The Coordination Between Urbanization And Ecological Environment In Five Major Urban Agglomerations

Since the reform and opening up,China’s urbanization has developed rapidly,and the rapid urbanization has disturbed the ecosystem and caused a series of ecological and environmental problems.The coordination between urbanization and ecological environment has become an important issue of urban sustainable development.As the highest form of urban development,urban agglomeration plays a core engine role in regional and even national economic development.With the rapid development of remote sensing technology and the convenience of remote sensing data acquisition,it has provided an important support for rapid monitoring of the ecologica l environment at medium and large scales and exploring the process of urbanization.Monitoring based on remote sensing has the unique advantages of high spatial resolution and high temporal resolution,and can objectively monitor the ecological environment and urbanization characteristics.In order to objectively evaluate the ecological environment and explore the impact of urbanization process,this paper starts from the five major urban agglomerations in China and calculates the Remote Sensing based Ecological Index(RSEI)and the Vegetation Adjusted NTL Urban Index(VANUI)based on night light remote sensing and daytime optical remote sensing from 2000 to 2020;The coupling coordination degree model(CCDM)is used to analyze the coupling coordination degree between urbanization and ecological environment.The RSEI did not consider air pollution,propose an Improved Remote sensing ecological index(IRSEI)that considers air pollution.The main findings of this study are as follows:(1)The urbanization level of the five major urban agglomerations continues to improve.The urbanization level of the Pearl River Delta urban agglomerations(PRDUA)is relatively high,and the urban development synergy is good,The urbanization development of the Yangtze River Delta urban agglomerations(YRDUA)is relatively rapid;The urbanization level of the middle reaches of the Yangtze River urban agglomerations(MYRUA)and the Chengdu Chongqing urban agglomeration(CCUA)is relatively low,and the urbanization level of the provincial capital is significantly higher than that of other cities,showing a significant three core distribution of Wuhan Changsha Nanchang and a dual core distribution of Chengdu Chongqing.The urbanization coverage of the five major urban agglomerations has continued to increase,with the PRDUA maintaining a leading position,followed by the YRD.However,the urbanization coverage of the MYR and the CCUA is low,and there is a significant gap between them and the three major coastal urban agglomerations.(2)Over the past 20 years,the RSEI of the five major urban agglomerations has shown an overall fluctuating downward trend,leading to a deterioration of the ecological environment.The number of low values RSEI pixels in the ecological environment of cities in the central and southern parts of the BTHUA,along the Yangtze River of the YRDUA,the central part of the PRDUA,the northern part of the MYRUA,and the middle part of the CCUA has increased,especially in urban areas where low value RSEI pixels gather,showing an expanding trend.From a specific city perspective,the changes in RSEI values can be divided into three categories.The first category is the urban agglomeration in the MYRUA,where RSEI values fluctuate and increase;The second type is the urban agglomerations of CCUA,BTHUA,and the YRDUA,with fluctuating and decreasing RSEI values;The third category is the PRDUA,with RSEI values basically unchanged.The IRSEI of the five major urban agglomerations shows an overall fluctuating upward trend.Except for the YRDUA,the IRSEI values of all urban agglomerations have increased.The IRSEI values of the YRD,PRD,and MYR range from 0.54 to 0.67,while the IRSEI values of BTH and CC are basically below 0.5,indicating poor ecological environment quality performance.The IRSEI in BTH shows a differentiation of high in the north and low in the south;The IRSEI of the YRD shows a differentiation of high in the south and low in the north,and the low value pixels of IRSEI expand towards the northeast wing;The IRSEI of the PRDUA shows a low central area and a high surrounding area,with a significant increase in the IRSEI value of the northwest wing;Low value IRSEI pixel clustering in the north and west of the MYRUA;The IRSEI low value pixels of the CCUA are mostly located in the central part of the urban agglomeration.(3)The average coordination degree of the five major urban agglomerations ranges from 0.3 to 0.6,indicating a steady improvement in overall transformation and development;The YRDUA,PRDUA,and the MYRUA have transitioned from moderate imbalance to a basic system,with BTHUA and CCUA stable at the basic coordination level.The overall spatial distribution is mainly characterized by severe imbalance levels.The coordination level of the three coastal urban agglomerations has significantly improved,and the number of high-level coordinated cities is constantly increasing.However,the coordination level of the two inland urban agglomerations is relatively stable,with a small and slow increase in the number of high-level coordinated cities.