Research on the Spatial Expansion Characteristics and Industrial and Policy Driving Forces of Chengdu–Chongqing Urban Agglomeration Based on NPP-VIIRS Night Light Remote Sensing Data

Abstract

In the context of rapid urbanization development, exploring the driving forces and characteristics of urban agglomerations’ spatial expansion not only enriches the depth and breadth of research on urban agglomerations’ expansion in China, but also has great significance for future urban development planning, rational utilization of land resources, and protection of ecological environment. This study selects nighttime light data to extract the built-up areas of the Chengdu–Chongqing urban agglomeration from 2012 to 2020, and uses urban expansion speed, urban expansion intensity, urban center of gravity migration, compactness, and fractal dimension index, combined with driving force analysis, to explore its development. The results show the following: (1) From 2012 to 2020, the Chengdu–Chongqing urban agglomeration expanded around Chengdu and Chongqing, and the expansion scale of each city first increased and then decreased. (The expansion scale is a comprehensive result obtained by using the formula of urban expansion speed and expansion intensity, indicating the extent of urban expansion.) (2) The expansion direction of the Chengdu–Chongqing urban agglomeration keeps close to Chengdu and Chongqing. The urban spatial form is not stable and begins to focus on urban interior filling. (Urban interior filling refers to the infrastructure construction and content enrichment and renewal within an urban built-up area.) (3) The spatio-temporal expansion of the Chengdu–Chongqing urban agglomeration from 2012 to 2020 is most affected by the levels of economic development and regional investment.