Research On City Size Of Coastal Areas In China From The Urban Functional Division Prespection

The sound development of urbanization will provide a strong driving force for the sustainable development of the economic. With the accelerating process of urbanization, China is facing the problems of reasonable selection and optimization of city size. It is not conducive to make full use of the existing urban land, public service facilities and other resources when the city size is too small. However, oversized cities often cause excessive utilization of resources, leading to problems such as rising congestion. Therefore, the priority of development among big cities, small cities, and coordinated development of big and small and medium cities has become the focus of academic debate. The reasonability of city size mostly studied in the existing literatures, which neglect the study on the division of urban function. The division of urban function is an important economic variable that influences the city size through the economic efficiency. In order to improve the utilization efficiency of urban resources and reduce the cost of the "big city" disease, this paper studies the reasonability of city size based on the criterion of city production efficiency, from the perspective of the division of urban function.The economic efficiency and reasonable size of the city are determined by the interaction of urban economic and noneconomic agglomeration. As the city size expands, the production efficiency of the city has an inverted U shape, increased firstly and then decreased. The expanded marginal revenue of city size changes with the division of urban function. Based on the Henderson’s city model, this paper expands it by adding division of urban function, urban network connectivity and other variables and employs the econometric models respectively, using the panel data of 114 cities of 11 provinces in the coastal areas of China except for Hong Kong, Macao and Taiwan from 2003 to 2012. Firstly, the indexes of divisions of urban function among the cities are measured and the spatial correlation tests are carried out. Secondly, the inverted U type features appearing in the production efficiency of the city and the city size are verified by using the panel data model. Thirdly, three types of spatial weight matrices are selected to implement the regression analysis of spatial lag panel model and spatial error panel model. Finally, from the perspective of the division of urban function, the reasonable scopes of the city size are estimated and policy suggestions for promoting city development are put forward, based on the regression results of the econometric model and the existing resources of the city.The conclusions of this paper are as follows. Firstly, there is obvious spatial correlation among the function divisions of cities. A certain distribution pattern has been found that central cities mainly undertake high value-added part of the industrial chain and the peripheral cities mainly undertake other parts of industrial chain. Secondly, the marginal revenue of the city scale changes with the division of urban function, and the reasonable division of the city plays an important role in promoting the city to reach its reasonable size. Thirdly, from the perspective of the division of urban function, unbalanced city scale development of coastal cities appears under the constraints of existing resources. The sizes of 17 cities such as Tianjin, Shanghai, Nanjing, Guangzhou, Shenzhen, etc. are relatively large and the sizes of about 65% of the coastal cities are relatively small. Each city should strengthen collaboration with its surrounding cities, optimizing the allocation of resources, exploiting fully home and abroad market and promoting coordinated development among big, medium and small cities.