The effect of regional integration on urban sprawl in urban agglomeration areas: A case study of the Yangtze River Delta, China

Urban sprawl refers to inefficient, disorderly, and low-density urban constructions that restrict sustainable development, in the context of rapid urbanization and industrialization. For decades, there have been debates on the evaluation, analysis, and control of urban sprawl. However, the relationship and impacts of intercity interactions on urban sprawl have been insufficiently discussed for urban agglomeration areas. This has resulted in an inadequate understanding of and policy implementation for sprawl in such areas. In this study, an empirical analysis was conducted on the Yangtze River Delta (YRD), one of the most socioeconomically developed urban agglomerations in China. This study first analyzed the dynamic spatiotemporal characteristics of urban sprawl in this area. Thereafter, the relationship between intercity connections and urban sprawl was explored, using a geographically weighted regression model and comparative experimental analysis. Finally, the challenges of urban sprawl were analyzed, to provide a decision-making basis for spatial territorial governance, management, and planning. The study found the following: (1) From 2005 to 2020, urban land in the YRD region increased by 9348.99 km2, occupying 68.73% of the increased land; (2) based on the comprehensive relationship between urban expansion, socioeconomic development, and urban function, urban sprawl was identified in the YRD region and was found to have mainly occurred from 2015 to 2020; (3) regional integration had a significant positive effect on promoting urban sprawl in the YRD region; and (4) spatial control strategies were provided for endogenous-driven, exogenous-driven, and development monitoring-type urban sprawl areas, based on urban sprawl characteristics and dynamic analysis.