Habitation environment suitability and population density patterns in China: A regionalization approach

The stunning disparity in population density between the southeast and northwest in China is highlighted by the Hu Line, a famous population demarcation line proposed by Huanyong Hu in 1935. This research seeks to uncover the underlying physical environment factors that shape such a contrast. Specifically, we propose a habitation environment suitability index (HESI) model to integrate topographic factors, climatic suitability, and hydrological condition into one comprehensive index, and then use a GIS-automated regionalization method termed REDCAP (Regionalization with Dynamically Constrained Agglomerative Clustering and Partitioning) to derive two demarcation lines based on the HESI and population density values, respectively. The two lines that divide China into two regions are largely consistent with each other. The result indicates that the population distribution disparity between the southeast and northwest is largely attributable to the difference in physical environments, and the barrier defined by the Hu Line is here to stay. In addition, the research also explores the (in)consistency between population density and HESI distribution patterns in various regions.