Study On The Spatio-temporal Pattern And Differentiation Of Rank-size Distribution Of Urban Land Expansion In Central Urban Agglomeration

Urban agglomeration is an advanced form of urbanization and an important carrier for regional competition.Quantitative cognition of the spatial-temporal pattern of urban expansion and pattern variation law of cities at different scales is of great significance to improve regional competitiveness,promote urban development and formulate appropriate space control strategy.Based on the data of land use status of the four stages(1990-2000,2000-2005,2005-2010 and 2010-2015)of Wuhan Urban agglomeration?Chang-Zhu-Tan Urban agglomeration and Zhongyuan Urban agglomeration during 1990-2015 and statistical yearbooks of Hubei Province,Hunan Province,and Henan Province,research on spatio-temporal pattern of urban expansion and pattern variation law of cities at different scales could be conducted by through indexes including the urban land sources,urban expansion rate,urban expansion index,center of gravity coordinates,fractal dimension and expansion intensity equal fan analysis method.Then the three urban agglomerations will be compared to find out their common rules and unused features in the expansion of urban land.Finally,the study on the driving forces of three Urban agglomerations was carried out.Results show:(1)The main source of urban land expansion in Wuhan urban agglomeration is farmland,it tends to change from a single source to diverse sources.The rate of urban expansion shows a "hump" shape and Wuhan and Huangshi is the slowest growing city;Regions with medium and fast expansion speed in different periods exhibit different shapes such as "U" or "//"type.The barycentric coordinates of Wuhan.Huangshi and Xianning develop towards the southwest;that of Ezhou,Huanggang and Xiaogan develop towards the northwest.The shape of Wuhan urban agglomeration is regular and smooth and the shape of the core expansion area is more complex and less stable than non-core extension area.Rapidly developing regions have a certain radiation effect on surrounding counties,such as main urban region in Wuhan.One-wing mode,multi-wing mode and fan-shaped mode exist at each stage.(2)The main source of urban land expansion in Chang-Zhu-Tan urban agglomeration is farmland and woodland,it tends to change from a single source to diverse sources.The rate of urban expansion shows a "hump" shape and Changsha is the fastest growing city;Regions with medium and fast expansion speed are located in the north of urban agglomeration;The barycentric coordinates of Changsha,Zhuzhou and Xiangtan develop towards the northeast,southeast,northwest;The shape of Chang-Zhu-Tan urban agglomeration is regular and smooth and the shape of Changsha downtown,Zhuzhou downtown and Xiangtan downton is more complex than other areas;Changsha downtown and Xiangtan downton have a certain radiation effect on surrounding counties;Urban expansion mode is mainly based on multi-wing mode and fan-shaped mode.(3)The main source of urban land expansion in Zhongyuan urban agglomeration is farmland and rural residential land,the type of source for urban expansion is relatively single.The rate of urban expansion shows a "hump" shape and Jiyuan and Zhengzhou is the fastest growing city;Regions with medium and fast expansion speed in different periods exhibit different shapes,such as semicircular or short "U" type.The barycentric coordinates of Zhengzhou develop towards the northeast;that of Kaifeng,Xinxiang and Jiyuan develop towards the southeast;the barycentric coordinates of Luoyang and Jiaozuo develop towards the southwest,when Pingdingsahn and Xuchang develop towards the northwest.The shape of Zhongyuan urban agglomeration is regular and smooth and the shape of Zhengzhou downtown,Kaifeng downtown and Luoyang downton is more complex than other areas;Rapidly developing regions have a certain radiation effect on surrounding counties,such as Zhengzhou downtown,Luoyang downton.(4)The main sources of urban expansion,urban expansion characteristics,core expansion areas' impact on surrounding counties,and pattern variation law of cities at different scales are same of three urban agglomerations,when the other sources of urban expansion,urban expansion rate,the shape of the cities and urban expansion mode are different.