Characteristics of Population Shrinkage in Inner Urban China and Correlations with Urban Growth Patterns

Urban shrinkage has led to urban decline and depopulation in Western countries. With the development of urbanization in China, urban shrinkage also appeared in China and gradually spread in many cities. The study of urban shrinkage helps to provide an important theoretical basis for the development of China's new urbanization and restore the vitality of urban development. This study used China's population data at a scale of 1 km from 2000 to 2015 to identify population increases and decreases over a long time series. Based on microscopic population changes in the city, the identification and characteristic analysis of urban shrinkage were performed, and the results were correlated with three modes of urban expansion in order to explore the relationship between the intensity of urban shrinkage and the pattern of spatial expansion. The results were as follows: (1) from 2000 to 2015, 80% of 366 cities in China experienced varying degrees of shrinkage, of which moderate and low shrinkage accounted for 64%. In addition, some regions such as northeast China, the Beijing-Tianjin-Hebei region, and southwest China have shown the spatial agglomeration of urban shrinkage phenomena. (2) Of the 291 cities where urban shrinkage has occurred in China, 99% experienced a weak shrinkage, while only 1% experienced a moderate shrinkage. In northern China, center shrinkage is the main pattern, while cities in southern China had an alternating distribution of marginal and central shrinkage. The type of urban shrinkage may be related to the speed of local economic development. Excessive speed of economic development and unreasonable mode of urban spatial expansion may lead to marginal shrinkage. (3) The expansion pattern of construction land in China from 2000 to 2015 was mainly outlying expansion, and population shrinkage was the most significant in this expansion mode. The compactness of the construction land expansion in China is inversely proportional to the intensity of the population shrinkage, and the lower the compactness, the stronger the intensity of the population shrinkage.