Definition Of Urban Hinterlands Of Chengdu-chongqing Economic Circle Based On Weighted Voronoi Diagram

Since Voronoi diagram is integrated with features of Vector Model and Raster Model, it has the characteristic of sphere of influence, lateral proximity and dynamical localization and transforms the issue of geometric calculation and raster calculation into that of graph theory, which conforms to the way of expression of spatial concept and provides a new method to study spatial analysis in digital environment. The paper marks off sphere of influence of central cities in Chengdu-Chongqing economic area based on weighting Voronoi diagram.On the foundation of theoretical integration related to city hinterland, this paper selects thirty-six central cities in Chengdu-Chongqing economic area, calculates their centrality strength and integrated transportation accessibility and then determines the hinterlands of these cities by using weighing Voronoi diagram and Breakpoint Model. Therefore, some findings can be concluded as follows:Firstly, the city hinterland can be defined as a system which is hierarchical, dynamic and integral and is shaped by requiring complementarity, intervening opportunity and transportability. The city is an open system and has economic relations with other cities which are the essential condition of developing modern city economy and the substance of forming a regional economic area. In order to study city hinterlands, economic relations between cities should be explored first so as to explain the essence of formation and development between central city and city hinterland.Secondly, the pattern of highway accessibility is centered in Chengdu decreasing from the center to the periphery and from the west to the east, which generally demonstrates the west and Sichuan are good and the east and Chongqing are relatively poor. Throughout railway transportation in Chengdu-Chongqing economic area, it can be seen that regional railway transportation is extremely imbalanced. The transportation in and around Chengdu, Chongqing and their traffic corridors is well equipped, while transportation in small and medium-sized counties and most of rural areas far away from central cities is relatively worse, which severely influences economic development of these areas, In these areas, transportation in Chengdu, Dazhou and the main city of Chongqing is best. As a whole, comprehensive traffic network in Chengdu-Chongqing economic area now has been basically shaped centering on Chengdu and Chongqing and is a radial pattern which regards railway and highway as the major trunk line, but this network is unbalanced.Thirdly, the development of central cities in Chengdu-Chongqing economic area takes on a "dual cores-multiple cities" structure in which "dual cores" refer to Chengdu and the main city of Chongqing and "multiple cities" are Nanchong, Yibin and Dazhou which reflect strong city comprehensive strength and have great development space in the future. This structure makes the regional balanced development possible. However, now regional development is not generally balanced. The development of some cities in Sichuan is relatively balanced, while the strength of other counties except for the main city is weak.Fourthly, by using the model defining the city hinterland, the paper analyzes the area of every central city hinterland and the superposition of city hinterland and administrative area. From the analysis, it can be concluded that the area of the east, city hinterlands in Chongqing, is smaller than that of the west, city hinterlands in Sichuan. The difference of area in every city hinterland is great and the greatest area is27times of the smallest one. Throughout the analysis of the superposition of city hinterland and administrative area, it can be found that one city’s hinterland is no longer limited to its own administrative area and is likely to belong to many other cities.