Abstract: Impervious surface has caused significant reduction in the process of urbanization. This research introduces the changing trajectory of impervious surface and growth pattern to investigate the spatio-temporal evolution of impervious surface in a case study in Ning-Zhen-Yang region. The results show that the urbanization process has driven impervious surface expanded continually during the study period, in which 301 km² of natural or semi-natural landscape is changed into impermeable landscape, with an average annual growth rate of 0.44%. The changing pattern of impervious surface has shifted from Zhenjiang to Nanjing in 2017, which means Zhenjiang grows severely before 2017, and Nanjing increases drastically after 2017. Moreover, the changing trajectory of impervious surface is mainly a one-time change. Such change is accelerating after 2017, and the vegetation is the primary source for urban expansion. The impermeable surface has spread to the urban fringe rapidly, which is the dominant growing mode in this region. Thus, an effective urban control is necessary to lead the development of urban boundary.

Key words: impervious surface, change trajectory, growth pattern, national geographic surveys, regional disparities