Multidimensional and multi-scale measurement and evolution trend simulation of urban sprawl

Urban sprawl is a critical challenge in the urban development trajectory of developing countries, necessitating precise measurement, trend projection, and strategic management to achieve sustainable urban growth. This study focuses on the Yangtze River Economic Belt (YREB) as a case region and introduces a comprehensive evaluation framework that incorporates multidimensional factors and addresses the scale effects of urban sprawl. We emphasize the value of a systematic geographical approach by quantifying urban sprawl through simulated scenarios and analyzing its driving factors. We constructed an innovative urban sprawl index (USI) to assess the degree of sprawl within the YREB. This assessment integrates two geographic models with an artificial neural network algorithm, enabling simulation of urban sprawl trends under two future scenarios for 2035. Additionally, two analytical methods were employed to identify the key driving mechanisms of urban sprawl in the region. Findings indicate a strong correlation between urban scale and the extent of urban sprawl: larger urban areas exhibit more pronounced sprawl, with agglomeration and morphological transformations identified as primary contributors to urban sprawl. The study further reveals an intricate association between urban sprawl and the compactness of urban internal structures. While both development scenarios offer distinct advantages, the Coordinated Development Scenario is projected to foster a more balanced urban expansion. The robustness of the evaluation framework was enhanced through simulation and an in-depth analysis of internal mechanisms, bolstering confidence in its applicability. We advocate for the adoption and continued refinement of this framework as a tool for promoting balanced urban growth. The strategic recommendations provided herein are vital for mitigating multi-scale urban sprawl, advancing economic development, and improving residents' quality of life across cities in the YREB.