City expansion and evolution of urban green space pattern in Chongqing (2000-2020)

Along with the fast development of Chinese economy and the speed of urbanization, it is inevitable to expand the city. As the center of economy in the Middle and West, Chongqing is expanding rapidly. However, while urban expansion drives economic development, it also exerts tremendous pressure on the urban ecological environment, with the changes in the urban green space pattern being particularly prominent. Based on RS data and statistics year books, this paper analyses the influence of urban expansion on urban green pattern from 2000 to 2020. The study finds that the area of urban construction land in Chongqing has expanded significantly, showing characteristics of central radiation and annular expansion. The influence of urban expansion on urban green pattern is mainly reflected in the decrease of farmland and nature, and the ratio of industry and residence. The analysis of the temporal and spatial characteristics of urban expansion shows that the urban expansion in Chongqing has experienced three development stages of “moderate-high-slow”, with the overall urban form showing a “southwest-northeast” strip distribution and tending to be compact and regular.