Does the urban sprawl matter in Yangtze River Economic Belt, China? An integrated analysis with urban sprawl index and one scenario analysis model

Urban sprawl is challenging regional sustainability in China due to its complex ecological and environmental impacts. This study aimed to effectively simulate and forecast urban sprawl in the Yangtze River Economic Belt (YREB), China. First, we measured the extent of urban sprawl from 1992 to 2015 based on the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) nighttime light data and an urban sprawl index (USI) at the administrative and river basin scales. Then, we established an urban sprawl scenario analysis (USSA) model that considered the extent of urban sprawl, the source level, ecological barriers and ecological resistance. Finally, we defined four scenarios to simulate the boundaries and spatial morphologies of urban sprawl in the YREB. The results indicate that the YREB will continue to spread at different scales and present unbalanced states under all urban area sprawl scenarios. Under the different scenarios, the upper reaches represented the most sprawling basin, the medium cities exhibited the greatest sprawl, and Cheng-Yu (CY) was the most sprawling urban agglomeration. The most sprawling cities were Chongqing, Kunming and Lijiang, accounting for 7.73%, 2.66% and 2.55% of the entire YREB, respectively. The urban land shared a similar sprawl trend across different years, increasing from 40,665 km(2) in 2020 to approximately 111,092 km(2) in 2035, for an annual growth rate of 6.93%. Thus, it is suggested that effective measures are needed to manage urban sustainability in the YREB, China.