Comprehensively Evaluation Of City Compactness On The Basis Of Grey Correlation

With the rapid development of urbanization, urban land utilization has been spatially expanded on the large scale, at the same time its internal land has long been in the status of roughly use, which also escaping a lot of problems in urban Violence development, such as inefficiently use, environmental degradation, traffic congestion and energy seriously waste and so on. All these problems have been highly attracted to academy, one of the core issues, the best mode of sustainable development for our urbanization, has become the currently most effective way to many scholars. Zhongyuan Urban is one of the important urban agglomerations in our country, and its level plays crucial to the urban sustainable development of society and economics in Henan Province.Therefore, it has been gradually emphasized, but the existing system is unusual, and the city compactness is even rare. Based on the advance of the compact city and reference of its theory, a systematic and comprehensive evaluation index system of urban compactness was established. Using Grey Relational Analysis evaluation model to evaluate relatively Compactness, while taking advantage of the entropy to measure absolute Compactness, using clustering method to classify objects with the Evaluation results, taking eight cities in Zhongyuan Urban Agglomeration as the object of this study. Eventually absolute level relatively compactness of eight cities in Zhongyuan Urban Agglomeration were calculated, and the corresponding suggestions were proposed in this study. The main conclusions are as follows:1. Urban compactness is a concept set that containing wide range of qualitative and quantitative aspects. In this study, based on deep understanding of the connotation of urban compactness, characteristics,theoretical basis, and according to the principles of the evaluation index of urban compact, in combination with the status of each city's development in Zhongyuan Urban Agglomeration ranging from the urban economy, urban land, urban population, urban transportation and urban spatial expansion, eighteen indicators were selected to form a compact city Comprehensive evaluation index system, the comprehensive evaluation index system could mostly contain the information of the city compactness.2. Gray relational analysis was used to measure city compactness of eight cities. The results shown that the group of eight cities in Zhongyuan Urban Agglomeration is relatively compact and the relative rank order of compactness:Pingdingshan city, Luohe City,Zhengzhou City, Luoyang City,Xinxiang, Jiaozuo City, Xuchang City, Kaifeng City. Among eight cities in Zhongyuan Urban Agglomeration, the relatively compact of Pingdingshan city is 0.638, which means is relatively compact and close to optimal value of the maximum degree; Luohe City, Zhengzhou City, Luoyang City, Xinxiang City, and Jiaozuo city center associated value relative compactness, were between 0.636 and 0.574, and they're relatively higher; Xuchang City and Kaifeng City, the values of the relative compactness were the smallest, less than 0.450, which were close to the smallest degree.3. While using entropy method to measure the absolutely city compact of Zhongyuan Urban Agglomeration, it's founded that all indicators of eight cities in Zhongyuan Urban Agglomeration were not balanced, so do the absolute individual compact city, indicating that urban economy, urban land, urban population, urban transportation and urban spatial expansion of these five aspects of each city in Zhongyuan Urban Agglomeration have space to be improved. Entropy method and gray relational analysis method were used to calculate the relative and absolute compactness.4. The studying eight cities can be grouped into three classes based on the clustering methods and the results of the absolute city compactness. The absolute compactness city urban agglomeration in the forefront of the Central Plains, a more balanced individual absolute compactness, namely, Zhengzhou City, Pingdingshan City, Luohe City; City center absolute compactness rankings, relatively compact single definitely more balanced, namely, Luoyang, Xinxiang and Jiaozuo City; cities rank behind the absolute degree of compact, single compact index is obviously not absolutely balanced, respectively, Kaifeng and Xuchang City, this result is consistent with the actual situation.5. In words, some suggestions were put forward in our study to improve city compactness, such as the rational use of urban space and other resources, mixed use urban land, uphold the public transport in priority, optimizing the distribution of population and improving the economic strength of the city.