Collaborative development and optimization strategies of the Huaihe River Basin Metropolitan Area: An empirical analysis based on nighttime light remote sensing

The Huaihe River Basin is one of the most densely populated regions in China, and also exhibits a significant net outflow of population, with an overall urbanization level below the national average. Achieving Chinese-style modernization in this populous and economically relatively weak region has important symbolic significance. As a key component of urban agglomerations and a major carrier of regional economic and social development, metropolitan areas attract both mobile populations and industrial agglomeration, facilitating more efficient resource allocation and factor mobility, and promoting coordinated regional integration. This study takes the metropolitan areas of the Huaihe River Basin as an example, utilizing nighttime light remote sensing data from 1992 to 2020 combined with socio-economic statistical data from relevant provinces and cities. The DBSCAN algorithm is employed to analyze the spatial clustering characteristics and evolution dynamics of the metropolitan areas. The results indicate that the metropolitan areas of the Huaihe River Basin play a critical role in regional development, with production factors in the urban economy highly concentrated, and scale, agglomeration, and diffusion effects becoming increasingly prominent. Based on current trends and future prospects, the study proposes the following policy implications: 1) establish regional growth poles and actively integrate them into national strategies; 2) strengthen water conservancy governance to enhance regional sustainable development; 3) optimize public service provision to support returning populations and promote regional growth; 4) drive industrial upgrading and structural transformation; and 5) break administrative boundary barriers to facilitate high-quality development in the Huaihe River Basin.