Analysis of the Factors Affecting the Degree of Urban Expansion: Taking Wuhan City as an Example

  Objectives  The heterogeneity of urban expansion degree at patch level deeply affects the evolution of urban physical morphology. Studying the factors and mechanisms affecting the degree of urban expansion are conducive to deepening the understanding of the expansion process, facilitating the control of urban spatial expansion and promoting the city's compact and sustainable development.

  Methods  Firstly, we measured the degree of urban expansion of Wuhan City by the proximity expansion index (PEI), and analyzed the spatial distribution characteristics. Secondly, we divided Wuhan City into circles and calculated the expansion degree and speed of each circle, the connection between expansion degree and speed was verified by correlation analysis. Finally, a spatial regression model was constructed to explore the impact of nature, social economy, transportation, and planning on urban expansion degree.

  Results  (1) The degree of urban expansion varied in space, the degree of urban expansion gradually increased from the urban peripheral to the outside. (2) The degree of urban expansion had a positive spatial correlation. (3) There was a strong positive correlation between the degree and the speed of expansion. (4) The traffic location, the control of planning, and the distance to the city center were the main influencing factors of the degree of urban expansion, and the influence degrees decreased in sequence.

  Conclusions  The degree of urban expansion was not disorganized in spatial distribution, but was affected by some factors such as traffic location, planning, and closely related to the speed of expansion. Analyzing the influencing factors of urban expansion degree can provide useful suggestions for urban space management and control.