Study On Expansion Model Of Construction Land In Wuhan City

China is in the period of rapid urbanization,the economy is growing rapidly,and the population and the size of the city are constantly expanding.But in the process of the rapid expansion of the city,some city blindly pursue the development strategy of "big city".This makes the "Urban diseases" more and more obvious.Its main manifestation are in the following aspects:the basic farmland is decreasing year by year;the residential land prices led to high tension;the traffic congestion and environmental pollution phenomenon are also serious.These negative factors make the environment and quality of urban life decline.More and more city are slowly losing their own historical and cultural personality because of the blind pursuit of modernization and internationalization.China is a developing country and urbanization is the inevitable trend of China's modernization.But many cities one-sidedly focused on large-scale city,new city and international city.These phenomenon have brought many hidden dangers.So the city expansion will inevitably become the focus of domestic and foreign scholars.Exploring the pattern of urban expansion is conducive to grasp the urban expansion rules,and can improve the level of urban planning and management of the implementation of effective policies.This paper selected Wuhan city as the research object,collected a large amount of historical data and established an appropriate urban construction land spatial information extraction technology system.On the basis of above,this paper analyzed and studied the temporal and spatial evolution rules and the expansion model of urban construction land expansion in the study area.The main work and conclusions are as follows:(1)Based on the analysis of the remote sensing image of Wuhan city,this paper had researched the information extraction method of construction land,the result showed that the comprehensive index method can achieve the image enhancement effect,and the better classification results were obtained by using the maximum likelihood classification method of supervised classification.(2)The historical expansion of Wuhan city were described by collecting a large number of historical data from 1949 to 1994.The expansion of construction land in Wuhan city in 1995-2015 was analyzed by using various expansion velocity index,those methods are expanded elastic coefficient,the allometric growth model,the gravity center model and the GIS spatial analysis method.The principal findings are as follows:1.the area of construction land increased gradually and the expansion speed first increased and then decreased from 1995 to 2015 in Wuhan city,which showed that the expansion in Wuhan became more and more reasonable;2.the expansion direction of construction land in Wuhan city is very obvious and the main expansion direction is in the southwest;3.Jiang xia district is the largest contribution to the whole expansion of Wuhan city;4.during 1995 to 2005,the construction land expansion rate was much higher than the rate of population growth,and then the expansion of construction land has been gradually unable to meet the needs of population growth from 2005 to 2015.(3)This paper considered the two dimensions of the whole and various administrative areas.Firstly,this paper analyzed the overall expansion mode of Wuhan city from 1995 to 2015 by using the method of public edge measure,the results showed that the evolution of Wuhan city's expansion mode changed from filled type to spread type and then to filled type,it indicated that Wuhan city was no longer so blind pursuit of expansion and began to expand in a planned way as in the past.In order to promote the city's sustainable development,Wuhan city's main focus was to constantly improve the existing building within the city sprawl and strictly control the urban sprawl.And then this paper defined the expansion model of 13 administrative districts in Wuhan city by using macroscopic convex shell model method and microscopic common edge measure method.The results showed that the seven central cities are all filled extension,the expansion pattern of other administrative district had gradually shifted from the filled expansion to the enclave expansion because of the establishment of four plates and four new projects in Wuhan city.