Landscape pattern indices for evaluating urban spatial morphology - A case study of Chinese cities

The impact of urban spatial form on infrastructure investment and ecological environment is as important as that of urban social and economic factors. It is of great significance to study the spatial distribution pattern of cities for deciding the direction of urban spatial development. In this paper, a total of 17 indices of urban spatial morphology, including those describing patch area, shape, and degree of urban agglomeration, were selected. Using the correlation, factor analysis, cluster analysis and non-parametric test of the indices, we studied the 146 cities in China. There was a strong correlation between some indicators, and through factor analysis, four main factors, including the "area-based agglomeration," " adjacency-based agglomeration," "shape," and "shape-area," explained 79.61% of the variance in the data set. Using cluster analysis, the 146 cities could be further divided into five clusters showing significant differences among them. There were strong regional differences in the spatial forms of Chinese cities, especially cities clustered in the Yangtze river delta, Pearl river delta, Shandong peninsula, Sichuan province. At the same time, megacities (populations greater than five million) had a more complex shape and the spatial axis of medium and small cities (populations less than one million) was more obvious. A more complex urban form would be associated with greater investment of infrastructure, and a more compact city would be higher economic resources, and greater development of public transport. From the perspective of resource saving, megacities were faced with the greater challenge of spatial form. The ecological demands of cities are equally important, and how to balance the ecological space e.g. water and green space in cities to obtain a reasonable spatial threshold should be explored in more detail.