Determinants of urban expansion and their relative importance: AÂ comparative analysis of 30 major metropolitans in China

Metropolitan has progressively emerged as a new form of urban governance. Understanding the urban expansion process and its determinants at metropolitan level should provide critical references for urban management and planning. Using time-series nighttime stable light data (1993-2012), this paper captures the full continuum of urban expansion process in 30 major metropolitans of China. Greater expansion intensity and faster expansion speed are observed in metropolitans along the eastern coast. Conversely, the metropolitans in northeastern China exhibit lower urban expansion intensity and speed. Potential determinants are selected based on extensive literature review from four categories: economic, social, demographic, and natural. Multivariable linear regression and variances partitioning are employed to identify and compare the determinants of urban expansion and their relative importance across the 30 metropolitans. Results show that urban expansion is not only subjected to different categories of determinants but also influenced by their combinations. More specifically, the identified determinants vary with metropolitans but present some similarities. Economic growth, industrial development, and economic structural transformation are the key economic determinants. Population and labor growth, population urbanization, and population structure act as essential demographic determinants. Primary social determinants include infrastructure construction, energy consumption, and real estate development, while dominant natural determinants are the amount and topology of available land. Cluster analysis is further applied and it generates three major driving forces profiles among the 30 metropolitans, with respect to the relative importance of different categories of determinants and their combinations. The driving force profiles should be useful for managers to set priorities in decision making procedure and develop optimal urban strategies. Our study is believed to advance the understanding of driving mechanism governing urban expansion at metropolitan level and further provide deeper spatial insights for international habitat research.