The Time-Scale Effects of the City-Size Hierarchy in China Based on Rank-Clock Methodology
LIU Miaolong, CHEN Yu, CHEN Peng, CHEN Jie (Dept. of Surveying and Geoinformatics, Tongji University, Shanghai 200092)
The theories of "Rank-Clock", "Rank-Distance Clock", and "Half-Life of City" suggested by Prof. M Batty, a famous urban geographer in the world, has been introduced in this paper. Using data of population and cities’ rank at and above prefecture for more than 50 years since the founding of the People’s Republic of China in 1949, the "Rank-Clock", "Rank-Distance Clock" and "Half-Life of City" depicting the evolving characteristics of cities' hierarchy in China have been researched and drawn up. As well, using some historical population data, the "Rank-Clock" characteristics of a few historical cities in China for the last 2000 years have been researched and discussed briefly. The outcomes of the "Rank-Clock" study indicate that variations of the "Rank-Clock" of metropolises in China appear more slowly and the cities' rank order is stable. As for the regional spatial differences, variations of the "Rank-Clock" of cities located in eastern China are more evident, and their rank order advances more quickly. Correspondingly, although variations of the "Rank-Clock" of cities located in northeastern China are also greater, the direction of variations is opposite compared with that of eastern cities and their rank order drops markedly. Furthermore, variations of the "Rank-Clock" of a few cities located in western and inland China are relatively small, and their rank order is kept beyond the top 100 cities for the study periods. The outcomes of the "Rank-Distance Clock" study show that changes of "Rank-Distance" in some cities with higher rank order are relatively small, and changes of cities with lower rank order and/or newly established cities increase more quickly. As to the whole urban system of China, the Rank-Distance changes placidly, only in the periods of 1980-1985 and 2000-2005, the significant changes of the Rank-Distance took place, representing two rapid urbanization processes occurred in the early days of "reform and opening up" and the beginning of the 21st century. The results of the "Half-Life of City" study display that as a whole city system of China, because of the shorter temporal span of the system, the "Half-Life of City" is not evident. Even if that is how things stand, taking the 1980s as a demarcation line of time, there is a clear duration difference between the forwards and backwards half-life of the top 100 cities. Just starting from the demarcation line, the speed of replacing old cities by new developing ones is quickening. The outcomes of the "Rank-Clock"study for some historical cities show that rank changes of the cities with political functions are closely related to their political status as old administrative capitals. And rank changes of the cities located in eastern and coastal areas of China are closely related to their geographical conditions and economic policy.