Study On Urban Growth Under The Ecological Security Pattern Of Dali

At present,the pace of urbanization in China is speeding up,and the urban growth rate is faster.In the process of urban growth,there are problems such as disorderly spreading and destruction of ecological environment.Therefore,in order to solve many problems in the process of urban expansion,the study of urban growth boundary has attracted more and more attention from scholars.The demarcation of the urban growth boundary can effectively curb the unlimited spread of the city.It plays an important role in coordinating the contradiction between the urban development and the contradiction between regional development and environmental protection.The delimitation of urban growth boundary is not only the protection of regional ecological environment,but also the guidance and restriction of urban growth space.The demarcation of the urban growth boundary is not only the spatial distribution of urban growth,but also an important way to ensure the ecological security of the region.It is the orderly development of the city under the premise of protecting the ecological security.There are many researches on the urban growth boundary,but how to select reasonable methods and select reasonable indexes to delimit the urban growth boundary which can ensure the ecological security and the sustainable development of the city is still the key and difficult point of the study.This paper chooses Dali as the research area to study the growth boundary of the city.As a typical mountain town,Dali city is rich in landscape resources,and its ecological environment is more fragile and sensitive.It is of great significance to study and explore the urban growth of Dali as a research area for its ecological security pattern.Firstly,the research status of urban growth boundary and ecological security pattern is sorted out,and the related concepts and theoretical foundation are studied.Then we choose biodiversity,geological disaster,water resources security,historical and cultural protection and other factors to construct single factor ecological security pattern.Next,the GIS superposition function is used to superimpose the single ecological security pattern and build the comprehensive ecological security pattern of Dali.Finally,delineate the growth boundaries of cities,including rigid growth boundaries and elastic growth boundaries.The definition of the rigid growth boundary is based on the identification of the important ecological land in the research area;then the laws and plans are considered,and the low security level is superimposed at the end,and the rigid boundary is finalized.In the process of urban growth simulation,the two factors of ecology and economy are selected,the resistance system of urban growth is constructed,the elastic growth boundary is simulated by the minimum cumulative resistance model(MCR),and the urban elastic growth boundary is classified,and the development time sequence of urban growth is finally determined.The main conclusions of this paper are as follows:(1)Firstly,we selected the factors of biodiversity conservation,geological disasters,water resources security and historical and cultural protection,and constructed the security pattern of the single ecological process in Dali.Based on the single factor security pattern,the comprehensive ecological security pattern of Dali is constructed,and Dali city is divided into low security level,medium security level,high security level and other areas by using the reclassification function of GIS.Next,delineate urban growth boundaries,including elastic boundaries and rigid boundaries.The rigid growth boundary takes into account the unsuitable construction areas in the planning,while the low safety level in the comprehensive ecological safety level is superimposed on the rigid growth boundary.Finally,a resistance factor system affecting urban growth is constructed,and the minimum growth resistance model(MCR)is used to simulate the elastic boundary of urban growth.(2)The delimitation of urban growth boundaries should take full account of the actual situation of the study area and adopt qualitative and quantitative methods.First,in the construction of the ecological security pattern,the selection of the single factor index should take full consideration of the actual situation of the research area,and the selection of the index should be both representative and practical.Secondly,the simulation of urban growth should not only follow the principle of ecological protection,but also consider the dynamic factors of urban growth.Only by combining the qualitative and quantitative methods,can we choose the evaluation index scientifically and rationally,analyze the data fully and rationally,and finally carry out the result in space and carry on the spatial analysis.(3)The analysis of urban growth with the combination of dynamic factors and ecological factors is helpful to solve the contradiction between urban sprawl and ecological protection in the process of urban growth.Rapid economic development and disorderly urban sprawl destroy regional ecological environment and threaten regional ecological balance,which is not conducive to sustainable development of the region.In the process of urban growth simulation,the dynamic factors and ecological factors of urban development can be taken into consideration,and the contradiction between urban growth and ecological security can be solved,and the sustainable development of the region can be promoted.