A mechanics-based theoretical framework of urban sprawl force: A case study in Nanjing, Wuxi, and Yangzhou, China

With the progress of urbanization, environmental challenges stemming from rapid urban sprawl have become pervasive. Consequently, research on urban sprawl has emerged as a crucial focal point in sustainable development efforts, emphasizing the need to understand the evolution characteristics and systemic mechanism of urban sprawl. However, existing research on the urban sprawl mechanism remains somewhat fragmented, lacking a unified research framework and theoretical model. In response, this paper proposes a theoretical framework for urban sprawl mechanics and constructs a unified analysis framework and an integrated urban sprawl force model. Furthermore, empirical analysis is conducted using Nanjing, Wuxi, and Yangzhou as case studies, measuring the integrated urban sprawl force and analyzing their urban sprawl characteristics through comparative assessments of the integrated urban sprawl force trends. The findings reveal distinct trends in the integrated urban sprawl force across Nanjing, Wuxi, and Yangzhou. Nanjing demonstrates a pattern of slow growth, Wuxi exhibits initial growth followed by a decline, and Yangzhou experiences rapid fluctuations in growth. As typical cities in different urban development stages, Nanjing, Wuxi, and Yangzhou exhibit change trends of the integrated urban sprawl force consistent with their urban development stages. The research framework and model of urban sprawl mechanics proposed in this paper offer a novel perspective and methodology for comprehending the current and future levels of urban sprawl. Moreover, this study furnishes valuable insights for relevant authorities in formulating policies to regulate urban sprawl.