Uneven growth of urban clusters in megaregions and its policy implications for new urbanization in China

Megaregions have become the principal geographic units for countries to participate in the global economy, which is often a composite of numerous urban clusters which are distributed in different cities. In China, a megaregion is regarded as a key urbanization platform, according to the National Plan on New Urbanization published in 2014. In this context, it is imperative to understand the spatial patterns of and the changes occurring in megaregions. For instance, what are the universal rules or differences related to urban cluster growth between different megaregions in the process of rapid urbanization, and are there differences in the growth of urban clusters with different sizes? Focusing on these issues, this study discusses the uneven growth of clusters in five of the largest megaregions in China using the rank-size rule, based on land-cover data interpreted from time-series satellite imagery during the period 1990–2010. The results show that the cluster size distribution of each of these megaregions obeyed the rank-size rule, and the size distribution of the clusters became more uneven and was tilted toward larger clusters between 1990 and 2010. These factors should be considered in the implementation of the National Plan on New Urbanization in China and the designation of urban macro planning and urban layout optimization in other countries those are experiencing rapid urbanization.