The Geographical Analysis of Megacities Through Changes in Their Individual Urban Objects

Abstract

This research utilized global coverage, annual, high‐quality land cover time‐series data to explore the urban growth process in the core area, and in several buffer zones, of Beijing, Guangzhou, Shanghai, and Tokyo. We developed a conceptual model in which growth is characterized at the per‐object level by four active growth events: introduction, establishment, dispersal, and coalescence, with a fifth inactivity event, stability. We developed a rule‐base which allowed the direct measurement of establishment, dispersal and coalescence from observed inter‐annual changes in the urban objects over time. By aggregating the object‐level events to the landscape level we showed that these three events generally followed a synchronous temporal trend in terms of magnitude within the core area and within each buffer zone. There was no evidence for a logical sequence of events through time. The identified events dominated alternately over time, although synchronicity in magnitude far outweighed any differences in proportion between them. This points to a single underlying urbanization process: urban growth with a specific dynamic rate. Interestingly, synchronicity was not generally observed between the core and buffer zones. This proposed object‐based method provides insights into the underlying urban growth process and could be used to build new urban growth models.