The Spatio-temporal Dynamic Characteristics、Hinterland And Fractal Dimensions In The Agglomerations Of Yangtze Delta

With the rapid development of urbanization in our country, urban spatial expansion develops more quickly, as well as its regional characteristics manifest more prominent, and it impacts regional spatial patterns largely. Moreover, it was urban spatial expansion and government’s improper regulation of urban spatial expansion seriously affects the regional sustainable development. Therefore, regional development must address the impact of urban spatial expansion and comply with the law of urban spatial expansion and trends of spatial evolution, and conduct comprehensive macro-control measures appropriately to co-ordinate regional development and urban spatial expansion. Hinterland supply several resoucres for the economic activity of Cenrtal City, the range and the quality of hinterland is very important to city’s development. Since20century, hinterland theory has involved in the developing process of economy geography and urban economics. Fractal theory is one of the latest theories of nonlinear science, and the fractal theory has been effectively used in studies of foreign cities. Fractal comes from the understanding of nature and the natural expression of Euclidean geometry in nature when incompetent, their nature is to further awareness of nature and nature’s grasp on the shape of things. The idea of fractal theory and practice in foreign countries has proved the ability to conduct studies of urban form. Paper concluded as follows:(1) The lighted area, night light intensity, compounded night light index (CNLI) and total night light index (TNLI) of16cities in the Yangtze Delta were derived from the DMSP/OLS night light data in2008and their correlations with urbanization statistics were calculated respectively, in which night light intensity proved to be an effective indicator to assess urbanization level. Construction land information of urban agglomerations in1998,2003and2008were also extracted from DMSP/OLS night light data after the determination of threshold value. Then the pattern and process of urbanization in the Yangtze Delta were analyzed and the expansion process of buildup area was categorized into several types. During the study period urban agglomerations in the Yangtze Delta had three typical spatial expansion modes of which the polygon mode could be observed in all the cities, the linear mode along main highways and railways, and the point mode mainly around the less important cities. In spite of the imbalance of urbanization level within the study area, the regional differentiation lessened gradually. According to the variation of threshold value from1998to2008,11cities including Zhenjiang, Changzhou, Yangzhou, Wuxi, Suzhou, Nantong, Huzhou, Jiaxing, Shaoxing, Zhoushan and Taizhou belonged to the filling-in dominant type, Nanjing, Hangzhou and Shanghai belonged to the first-extension-then-filling-in dominant type, and Taizhou and Ningbo belonged to the first-filling-in-then-extension dominant type.(2) Hinterland supplies resources for the economic activities of central cities,so the rang and the quality of hinterland are very important to city’s development. Night light index is the urban synthetical scale value.In this paper, the Yangtze Delta divided into4320grids, the scale of which is5km×5km,with the support of the ArcGIS software.Based on field-strength model, the paper calculates the urban influence of16cities in the Yangtze Delta and it finds the features and rules of the hinterland in the Yangtze River Delta in1998-2008. By comparing their area with their unicipal boundaries, the total hinterland and the hinterland in the adminstrative regionalization of the Zhenjiang, Ningbo, Jiangxinm and Suzhou increased from1998to2008; the total hinterland and the hinterland in the of the adminstrative regionalization of Nanjing and Yangzhou declined. The hinterland in the adminstrative regionalization of Shanghai and Taizhou is unchanged, howerver, the total hinterland of Shanghai is definitely declinced.The results of the research can be referenced to the adjustment of administrative districts in the Yangtze River Delta.(3) Adminstrative regionalization adjustment will lead to spatial structure variation of urban agglomerations, and thus exert a significant impact on the development of regioanl urban system and economy. In this paper the Yangtze Delta was chosen as the study area and the related basic data was downloaded from National Fundamental Geographic Information System (NFGIS). The software ArcGIS was employed to calculate the fractal dimensions of urban agglomerations in the Yangtze Dleta during the period from2000to2008. Three kinds of fractal dimensions, namely, the aggregation dimension, the grid dimension and the spatial correlation dimension, were used to describe the spatial aggregation of urban agglomeration, the spatial equlibrium and the spatial interaction between urban agglomerations as well. The adminstrative regionalization adjustment in the Yangtze Delta included both the internal adjustment and the outwards expansion of municipal districts. The influence of Shanghai and Nanjing as the central cities has been strengthened while that of Hangzhou weakened. Urban agglomerations have been much more evenly distributed within the region as well. Integration of traffic network has promoted the spatial interaction of urban agglomerations and propelled the development of the region as a whole.