Research On Multi-scale Urban Sprawl Measurement Based On WUP Optimization Mode

As China’s urbanization process continues to accelerate,the level of economic development has been rapidly enhanced,while at the same time many of China’s urban fringe areas are experiencing uncontrolled land development and the blind sprawl of construction land is serious.Urban sprawl can lead to traffic congestion,massive erosion of arable land,air pollution,inefficient land use,and a series of other negative impacts,posing a major challenge to sustainable urban development.Scientific measurement of urban sprawl is beneficial to the optimization of urban land use layout and rational allocation of resources,and can promote the modernization of China’s land spatial governance system and governance capacity,which is an important element to achieve land conservation,intensive land use,intelligent urban governance,highquality urban development and the construction of beautiful China.To address the problems of scale,single unit of measurement and lack of linkage and difference between single cities and urban agglomerations in the existing urban sprawl measurement studies,this paper constructs a localized WUP(Weighted Urban Proliferation)model,firstly,takes Beijing as the study area,and explores the influence of different scales of urban areas,urban buffer zones and municipal districts on urban sprawl measurement.The spatial differences of urban sprawl between 2000 and 2020 are analyzed in different units such as 1 km2 grid,districts and counties,and main functional areas;secondly,the Beijing-Tianjin-Hebei urban agglomeration and Yangtze River Delta urban agglomeration are used as research areas to investigate the connection and differences of urban sprawl measures between single cities and urban agglomerations.The research results show that:(1)The localized WUP model can obtain spatially continuous urban sprawl measurement results,realize urban sprawl measurement at different study object scales,and evaluate the spatial and temporal differences of urban sprawl in different units within cities.This paper gives the specific methods for determining the HP parameters for single cities and urban agglomerations.(2)From 2000 to 2020,the highly spreading areas in Beijing keep shifting to the periphery of the urban area with time change.The urban sprawl is highest at the urban scale in 2000,and at the 3 km buffer zone scale in 2010 and 2020.The urban sprawl is influenced by traffic radiation,and the high sprawl area gradually evolves from the area near the expressway to the area around the urban functional expansion area.The sprawl of Shunyi,Tongzhou and Daxing is higher and has increased the most over the past 20 years,while the sprawl of the six districts located in the central urban area has decreased,and the sprawl of the core area of the capital has always been the lowest.(3)From 2000 to 2020,the urban sprawl of all cities in the Beijing-Tianjin-Hebei and Yangtze River Delta urban agglomerations showed an increase over time;analyzed by province and city size class,the urban sprawl results of the Beijing-Tianjin-Hebei and Yangtze River Delta urban agglomerations showed different patterns of change;comparing and analyzing the two urban agglomerations,it was found that the overall urban sprawl of the Yangtze River Delta urban agglomeration was lower,but the urban sprawl development was greater during the study time interval.The innovations of this paper are:(1)for the first time,three scales of urban areas,urban buffer zones,and municipal districts are used to explore the scale effects of urban sprawl measurement and the differences in spatial and temporal distribution of intracity sprawl;(2)a method is proposed to determine the HP parameters when applying the WUP model to carry out urban and urban cluster sprawl measurement.In summary,the localized WUP model can realize urban sprawl measurement at different scales in the study area,reveal the scale effects of urban sprawl measurement as well as the spatial differences and dynamic evolution of urban sprawl in different study units within cities,and the research results can provide a reference basis for urban governance,urban renewal and territorial space optimization in the corresponding regions.