Analyzing the ecological environment and urbanization characteristics of the Yangtze River Delta Urban Agglomeration based on Google Earth Engine

As the highest spatial organization of urban development, urban agglomerations will inevitably have a coercive impact on the regional ecological environment during the rapid urbanization process. How to balance the ecological environment and the development of urbanization has become a problem worthy of attention. Taking the Yangtze River Delta Urban Agglomeration (YRDUA) as an example, based on the Google Earth Engine platform, this paper analyzes the ecological environment, urbanization intensity and the coupling and coordination characteristics of the two in the development process by integrating the daytime optical remote sensing and nighttime light remote sensing data. The results show that: 1) in the past 20 years, the Remote Sensing-based Ecological Index (RSEI) of the YRDUA has been rising steadily, and the ecological environment has shown a trend of improvement, but the regional differences are still significant. 2) The Comprehensive Nighttime Light Index (CNLI) can accurately depict the urbanization level of the urban agglomeration. During the research period, the YRDUA has formed a multi-level urbanization pattern from east to west, in which the high-intensity urbanization cities are concentrated in Shanghai and its surrounding area, while the low-intensity urbanization cities are distributed in the west of the urban agglomeration. 3) The Coupling Coordination Distance Model (CCDM) based on CNLI and RSEI can effectively identify the coupling coordination degree of urbanization and ecological environment in urban agglomerations, and divide cities into good coordination type, primary coordination type, urbanization lag type and ecological environment lag type according to quadrant characteristics.