Study On Spatio-temporal Evolution Of Urban Development Level In China

Cities are playing an important role in the regional and national development, as they are an agglomeration center of population, political, economic and cultural center. Since the 21st century, Cities have entered a stage of rapid development in China, and the engine role they are playing has become more prominent in regional and national development. Therefore, the cities have become a driving force and source of regional development in China. However, they are also facing various types of sustainable development issues and contradictions. The development model of the leading ahead of land urbanization and the inadequacy of population urbanization bring a series of problems, such as resource depletion, environmental pollution, urban system architecture imbalance, rural-urban differences expanding, uneven development of regions and other issues. These issues force us to rethink the meaning and development model of urban development. The 18th National Congress of the Communist Party of China (CPC) report and the "twelfth five-year plan" also proposed to enhance the connotation of urban development, to plan the urban layout and form scientifically, and to optimize the national spatial development pattern. While close attention are paid to the growth of population and land scale, the focus of urban development in China will gradually shift from outward expansion to the enhancement of comprehensive benefit. And we are more concerned about the integrated collaborative development of a wide range of economy, society, ecology, and culture.Thus, in the crucial process of China’s economy transition and development and the critical period of rapid growth and urbanization, there is an urgent need to explore the following three central issues:How is the level of development of Chinese cities? What changing trajectory and differences they exhibit in the geospatial features? How is the spatial and temporal evolution pattern of the urban development? In this paper, the three core issues taken as the starting point, we select all the national cities for the study, and conduct many theoretical discussions and empirical researches around three subjects, which are the connotation of the level of urban development, the construction of index system and evaluation model, and the analysis of spatial and temporal evolution model.(1)The multi-dimensional and multi-level index system to evaluate urban development level is established on the countrywide scale, and the evaluation result was further analyzed on whole. The results show spatial difference of urban development level is significant and unbalanced from 2001 to 2010. The level presents lying "S" distribution characteristic in all. It exists as "spindle-shaped" from rank system and is related with city size. However, there is no correspondence between them. Thus city size cannot entirely reflect the overall level of urban development level.(2)The generalized entropy model and Gini coefficient decomposition are adopted to analyze the difference resulting from the different regions or different sizes in stages. The study found that, from the view of geographical structure, internal difference in western region is the first caused the national overall differences. The four regional differences is the second dominant factor. The internal differences in the east shrink or expand, which have little effect on the overall differences. From the city size, the differences between the different sizes are the main cause as a whole, and the second determining factor is the large cities. However their influence is declining. Moreover, the influence of extra cities and supersize cities is small. The level of urban development of China shows a clear differentiation trend, which is consistent with the fact that our regional development level is obviously different. Therefore, we should reduce internal differences between the west region and four regions, and foster large and medium-sized cities development, narrowing regional development differences to achieve the strategic objectives to be done.(3)Introducing graphics thinking of "Standard Deviation Ellipse", five dimensions and two states model for China’s city development are constructed from the perspective of spatial visualization. With Hu Huanyong population line (Hu-line) as a reference, the spatial centers, distribution range, shape, orientation, spatial concentration and spatial differences of urban development level, are conducted the thorough research. Our research shows, spatial concentration of urban development level increases by an average 6.22% per year from 2001 to 2010, the geographic range shrinks 623.57 meters per year on average. The spatial variation coefficient of city development level ellipse (CDLE) is 15.45% for population distribution, and about 93% of distribution range is located in the southeast of Hu-line. CDLE axis is parallel to that of population ellipse and Hu-line. Besides, city development distributed is mainly gathered at Hu-line southeast, approximately 25% on the continent’s land area. And CDLE’s shape is similar to population ellipse. Therefore, promoting urban development level and efficiency at nearby the east-west axis of CDLE, and actively participating "One Belt And One Road" national strategy, has great significance for the balanced harmonious and healthy development of the cities nationwide.(4)The advantage of Exploratory Spatial Data Analysis (ESDA) is fully exploited to investigate the characteristic of spatial and temporal evolution from global and local spatial autocorrelation for Chinese urban development level. Studies have shown that the spatial clustering of urban development level experienced a degree of "increases-small magnitude lower volatility" in 2001-2010, the dynamic evolution changes from "clusters" gathering gradually to the "strip" agglomeration. "Hot spots" areas and "cold spots" areas of urban development have obvious polarization trend. Eastern cities of China have high-value features gathering significant yearly, and the evolution shows the performance that is "piece"-> "group"-> "band".(5)The synergistic effect among geographic features is emphasized, thus a partial least squares regression model (PLSR) is used to extract the strongly correlated geographic factors with urban development level. Then the two geographic factors were spatially interpolated using the Co-Kriging Model to construct the optimal temporal and spatial trend surface of CDL. Further the temporal and spatial evolution patterns are identified from spatial continuous surface and contour angle. Studies have shown that the overall level of the development of Chinese cities presented a "circle" pattern obviously, but the "fan-shaped" pattern developed from "cluster" pattern and "point axis", which constituted by high value areas of local development level, has appeared. The level of the development of national cities presented multi-center network and "polycentric cohesion" and "network-like outreach" patterns of development. Therefore, important growth poles network should be constructed in the Midwest and northeast regions, the spillover effects of growth poles should be fully used, which is helpful to promote the development of land and space patterns.The results provide a quantitative basis for the China’s urban development layout formulation and territorial development strategy in the future, and also provide valuable reference conclusion for the improvement of urban construction system, the promotion of regional coordinative development and the optimization of land development space patterns.