Study On The Variation Characteristics Of Levels And Sizes Of Towns Based On TM In Jianghan Plain

Urban grade scale structure is an important part of urban system, which mainly studies the spatial composition and the law of development in different levels and sizes of towns within a country or a region. It plays an important role to analyze temporal and spatial patterns of urban grade scale structure in understanding the development stage of urban system. The temporal and spatial patterns of urban grade scale structure can demonstrate the spatial distribution, temporal development law as well as the concentration or discretion degree of urban population size within different levels and sizes of towns.In this study, the temporal and spatial patterns of urban grade scale structure in Jianghan Plain have been studied. To analyze the characteristics of temporal and spatial patterns of different levels and sizes of towns, the TM data in the year of 2010 and land use database has been used. The research conclusions in this study are as follows:(1) There are differences in the temporal and spatial distribution of different levels and sizes of towns in Jianghan Plain. The number of towns within 100-500hm2 or larger than 500hm2 has increased, while the number of towns within 50-100hm2 or smaller than 50hm2 has decreased during the study period.(2) The areas of towns which are within 50-100hm2 or smaller than 50hm2 have decreased greatly during the year of 2000-2010, while the areas of towns which are within 100-500hm2 or larger than 500hm2 have increased during the same period.(3) There are great differences in the number of towns by administration grade. With the increase of administration grade of towns, the net growth rate of urban area increases. The higher the administration grade, the greater the net growth rate in urban area.(4) The concentration degree of urban system in jianghan Plain rise during the period of 2000-2010, and the imbalances of urban system increase too.