Quantifying spatiotemporal patterns of urban expansion in China using remote sensing data

China is undergoing a major transformation of its urban structure due to its rapid economic and population growth. It is critically important to properly characterize urban expansion before developing a comprehensive understanding of urbanization processes. Using multi-temporal remote sensing data of land-use change, this paper employs urban expansion rate and intensity as well as several landscape metrics to conduct a quantitative analysis on urban expansion patterns of 18 cities in different regions in China. The results provide clear insight into the spatial heterogeneity of the urban expansion rate and intensity going back to the late 1970s. Overall, before 2000, urban expansion rate and intensity was significantly higher in the eastern region than that in the middle and western regions. After 2000, this trend reversed. The analysis showed that cities in the late 1970s had the highest spatial heterogeneity, which then significantly decreased from that point up to 2008. From the late 1980s to 2008, Chinese urban expansion patterns changed from patch infilling to patch margin expansion. Spider diagrams comprised of six landscape metrics were shown to capture characteristics of urban form and structure changes at four time stages. The 18 cities were divided into four groups based on spider diagram shape. The spider diagrams show that the first group of cities exhibit relatively stable shapes, while the other three groups of cities exhibit relatively irregular shapes. China's eastern and middle cities show a greater degree of active urbanization than China's western cities