Identification and analysis of urban Shrinkage risk based on residential property values

With the adjustment of the economic structures and the slowdown of development, urban shrinkage has become a common phenomenon, especially in developed countries. In contrast, for developing cities, there is a special phenomenon of urban shrinkage, that is, border expansion and space shrinkage coexist. In view of this situation, it is difficult to effectively identify the signs and trends of urban degradation and space shrinkage by only studying the macro scale of urban space. The purpose of this paper is to build an evaluation model of urban space shrinkage risk, which can be run for the whole process of urban space development. It can also be applied to diverse scales of urban space and identify the mechanism of the transformation and diffusion of the space shrinkage risk on the time scale and the space scale. This study took Jinan City in China, a typical second-tier city, as a sample of urban shrinkage and took the urban residential property values as the key index to evaluate the shrinkage risk. The results show the risk of urban space shrinkage on the micro-scale. This paper analyzes the transfer and spillover effects of the urban space shrinkage risk by using Moran's spatial correlation tools and transfers this micro space shrinkage risk to the macro level to analyze the characteristics and trends of the typical urban shrinkage in China from the macro level. According to the Moran's Index, the urban space was divided into four types: collapsed areas, emerging areas, blocking areas, and revitalized areas. Based on this classification, the back-propagation neural network and decision making trial and evaluation laboratory (BPDEMATEL) model was used to analyze the influencing factors for each spatial type. It measured the degree of cause and centrality of each influencing factor and identified the contribution and function of the influencing factors of the spatial risk for the whole urban spatial system. It identified the basic, characteristic factors of the shrinkage risk for each type of urban space and analyzed the core reasons for the shrinkage risk of various types of urban space. The main conclusion of this paper is that the sparse distributions of the economic and population densities will lead to the fracturing and isolation of the urban space and increase the risk of urban space shrinkage. The shrinkage risk of the urban interior space presents different modes and driving mechanisms.