Tracking the history of urban expansion in Guangzhou (China) during 1665–2017: Evidence from historical maps and remote sensing images

Urban expansion has become one of the most intense types of land use transitions worldwide. How to theoretically explain urban expansion under different political regimes from the perspective of land use transitions is a vital question. We therefore revealed the urban expansion in the Guangzhou metropolitan area during 1665–2017 by using historical maps and remote sensing images. The results showed that the international trade policy directly affected urban expansion and the emergence of new buildings with educational and religious functions during 1665–1907. During 1912–1938, the political regime change in the Nationalist Era caused a climax of urban expansion. However, urban expansion was again obvious in the Socialist Era after 1949, and China's reform and opening-up policy in 1978 further promoted Guangzhou’s urban expansion. The direction and scale of Guangzhou’s urban expansion were in line with policies and urban planning. Moreover, land policy and urban planning triggered more orderly urban expansion than socioeconomic drivers, especially in political regime change periods. The declining overall urban expansion speed from 1860 to 2017 illustrated that urban expansion triggered land use transitions and that conflicts tended to stabilize. The abovementioned evidence indicates that variance in the level of social and economic development caused by policy obviously affected the degree of urban expansion and ultimately tended toward orderliness. Our research first contributes to revealing the urban expansion that occurred under different political regimes using long-term hybrid spatial data and then theoretically illustrates the driving mechanism of urban expansion affected by land policies, urban planning, and socioeconomic development under different political regimes from the perspective of land use transitions.