A Study On The Formation And Extension Of The Urban Agglomeration In The Yangtze River

Since the reform and opening up, China has achieved rapid economic development. Along with the development of industrial economy in our country, the scales of city continues to expand which promote the cities’boundary connect with each other. Under the background of intercity traffic network rapidly development economic interaction between the cities increase, and the cities start development as a group. The Yangtze River Delta Megalopolis is the most successful megalopolis in China, it created 16.7% of national economic output only used 1.1% land of China in 2014. In the past 10 years, the Yangtze River Delta Megalopolis’population increased rapidly, super urban boundary expansion and small and medium-sized cities in the rapid rise, and it is becoming the world-class megalopolis.By review Thunen-Alonso "isolated island" single city model, Henderson city system, Fujita-Ogawa multi-center city and Mori’s urban system, we abstracted some important factors such as rent and scale. Then, we build a megalopolis expansion model under the framework of new economic geography. By which, we put forward the hypothesis of efficiency from some aspects as land utilization efficiency, industrial agglomeration effect, human capital effect, traffic network effects and spatial spillover effects. Hypothesis include:(1) the land utilization efficiency, industrial agglomeration effect, the effect of human capital is the main factor that improve the production urban efficiency; (2) join the megalopolis promoter the city’s land use efficiency, industrial agglomeration effect and human capital effect, which promote the urban efficiency;(3)As transportation network deepening can increase integration between cities, megalopolis’efficiency will arise;(4) new member of megalopolis can always gains from center city (big city) or core city (small and medium-sized city), but the center city or core city will lose if megalopolis expand too much.Using the panel data of 37 cities of the Yangtze River Delta Megalopolis during the period 1999 to 2013, with modern econometric methods such as fixed effects panel, difference-in-difference, quartile regression and spatial econometrics, we confirmed the theoretical hypothesis and get the following seven main conclusions:(1) the efficiency of land use, the effect of industrial agglomeration and human capital are the most important factors that promoter urban efficiency. Join Yangtze River Delta Megalopolis has a significant positive effect on urban efficiency, but that is mainly through improving the efficiency of land use and industrial agglomeration. (2) after the new member join in, the total efficiency of the Yangtze River Delta Megalopolis increases. But that cannot reduce the gap between groups. (3) the construction of the high-speed traffic network promote the integration of megalopolis, which have direct and indirect effects on the efficiency of Megalopolis. High-speed railway line between Shanghai and Nanjing together with shanghai and Hangzhou have significant positive impact has positive effect on urban efficiency by land use efficiency, industrial agglomeration effect and human capital effect. While high-speed railway line between Beijing and Shanghai by industrial agglomeration, and high-speed railway line between Nanjing and Hangzhou by human capital to promote urban efficiency.(4) as the development of intercity traffic, High-Speed railway is more important to cities and the hierarchy of traffic network is constantly upgrading.(5) after the expansion of the Yangtze River Delta megalopolis, as a whole, space interaction and spillover effects of Yangtze River Delta Megalopolis are significantly strengthened. Only new members could gain from expansion at the expense of other cities.(6) Before the expansion of the Yangtze River Delta Megalopolis, Nanjing is the city which spillover to other non-central cities and Hefei has a significant negative spillover. However, after the expansion of the Yangtze River Delta Megalopolis, Shanghai becoming the only city which spillover to other non-central cities. Sub-center cities did not become the center of region, and Yangtze River Delta Megalopolis did not form multi-level "core-periphery" structure.According to the conclusions, we could get following policies. First, the formation of megalopolis need to guide by the market instead of government. Second, the development of the megalopolis needs improve the land utilization efficiency, promote the formation of human capital and industrial agglomeration effect. Third, the development of the megalopolis needs to build hierarchy of traffic network, which need develop the high-speed railway and highway. Fourth, the development of the megalopolis need to balance gains between old and new members. Fifth, expansion of megalopolis need the foundation traffic network and economic interact. Otherwise, it will loss efficiency. Sixth,the expansion of megalopolis needs a new city center or core city, multi spatial structure is an ideal structure.