Spatial Identification And Formation Mechanism Of Urban Shrinkage In China

Cities do not always grow.As a new topic of current urban development,urban shrinkage has attracted extensive attention of many scholars at home and abroad.In the1980 s,western scholars put forward the concept of urban shrinkage to describe the process of urban transformation and its influence on a global scale.For China,economic growth brought by the reform and opening up in some areas is unsustainable,part of the resources city,export-oriented industry and trade city,metropolis peripheral cities appeared different dimensions such as population,economy,space,different degrees of shrinkage phenomenon,to aspects such as economy,society and space has brought many bad effects,the challenges of urban contraction cannot be ignored.Urban shrinkage is global,local,multidimensional and complex.Therefore,it is necessary to strengthen the spatial identification and mechanism research of different types,scales and scales of urban and regional shrinkage.Based on China's 2000-2015,more than 295 local and city as the research object,based on remote sensing data and GIS technology,selection of multidimensional index to measure and spatial recognition,build the shrinkage degree of population,economic contraction degree,space contraction degree index,above ground level and from three dimensions to identify China city contraction degree and its spatial distribution,identifying single dimension shrinkage of cities.With the help of MATLAB software,polygon area method was used to calculate the comprehensive shrinkage degree,identify the spatial distribution of the comprehensive shrinkage degree in China at the grid level,identify the comprehensive shrinkage type cities in China,and explore the agglomeration and difference of the spatial distribution in different periods.On this basis,different types of shrinking cities are divided and their spatial distribution characteristics are analyzed.Finally,the driving factors of urban shrinkage in China are explored by using geographic detector,and the formation mechanism is analyzed to put forward policy suggestions.The main conclusions of this paper are as follows:(1)There are 108 cities with shrinking phenomenon,including 88 cities with shrinking population,32 cities with shrinking economy,33 cities with shrinking space and 22 cities with comprehensive shrinking.From the perspective of spatial distribution,it is mainly distributed in the three provinces of Northeast China,which indicates that some cities in the three provinces of Northeast China contracted at different time periods and varying degrees in population,economy and urban space during 2000-2015,which is a high frequency area of shrinking cities of different dimensions in China.In summary,the evolution of urban shrinkage in China from 2000 to 2015 basically shows three trajectories: the overall contraction represented by the resource-based economy in Northeast China,the partial contraction represented by the export-oriented industrial and trade cities in the central and eastern regions,and the dependent contraction represented by the small and medium-sized cities outside the western metropolis.(2)The number of shrinking cities is the largest in medium-sized cities(cities with permanent urban population > 500 000 and less than 1 million),and it is concentrated in the northeast of China.Among coal resource cities,the number of population shrinking cities occupies the first place.Through the analysis of the spatial characteristics of urban shrinkage of different sizes,the paper finds that the frequency of urban shrinkage is the highest in medium-sized cities,which reflects that medium-sized cities are the most frequent area of urban shrinkage in China.Among the resource-based cities with shrinking population,the number of cities with coal resources and non-renewable resources is in the majority.The number of other shrinking cities is also in the majority of non-renewable resources.(3)The shrinking cities in China can be divided into five categories according to the degree,dimension and scale of the shrinking cities: adjusting shrinking cities,smart shrinking cities,limiting shrinking cities,expanding shrinking cities and overall shrinking cities.The spatial distribution of different shrinking cities is characterized by the overall shrinking cities in the northeast,the adjusting shrinking cities in the central and southern regions,and the coexistence of various shrinking cities in the central and northwestern regions.On the whole,the shrinking type of most cities in China is adjustment shrinking type,that is,the population scale is shrinking,but the scale of economy and land use is expanding.This type of cities are mainly distributed in Guangdong,Hunan,Jiangxi and other provinces,with the most concentrated distribution in Guangdong Province.In Heilongjiang Province,the contraction of the city is the overall contraction.(4)The agglomeration of urban contraction in China has a positive spatial autocorrelation.Using global autocorrelation and local autocorrelation methods to analyze the agglomeration state of shrinking cities,the phenomenon of urban contraction in China shows an obvious high-high(H-H)agglomeration and low-low(L-L)agglomeration in space.The local agglomeration characteristics showed a cluster-like distribution,and the urban shrinkage areas were mainly concentrated in the three northeastern provinces and the western region.The non-shrinking areas are mainly in the southeast coastal areas where the cities are relatively developed.The other types of agglomerations show dynamic changes,which mainly show the characteristics of changing from zonal distribution to cluster distribution,from sporadic distribution along the coast to agglomeration in the southeast coastal area gradually.(5)The factors of urban shrinkage in China are complex and varied,but population development and economic level have a significant impact on urban shrinkage in China.It is found that the shrinkage of Chinese cities is influenced by multiple factors such as population growth rate,economic level,industrial structure and traffic location,forming an influence system of two main factors and multiple auxiliary factors.