Study On The Scale Hierarchy Of Urban Public Green Space Based On Fractal Theory

The urban public green space is an important part of many urban ecosystem systems and assumes the functions of natural ecology,social economy and culture,and is a combination of artificial construction system and natural ecological environment.It is important space carriers to improve the urban environment and promote the sustainable development of cities.As the most important media for intimate contact between urban residents and nature,urban park green space has many problems in its development research.For example,urban park green space lags behind its own development,planning science and utilization efficiency of park green space need to be improved,Structural characteristics of the scale characteristics of the lack of quantitative research.In order to promote the efficiency and fairness of urban green space resource allocation and to strengthen the scientificity of the park green space planning and layout,this paper puts forward that the system features,distribution and scientific optimization should be discussed in depth based on the fractal theory based on the scale of park green space.From the perspective of the fractal city theory,this paper uses the fractal mathematical model to analyze the fractal characteristics of the park green space in different cities,summarizes the distribution characteristics of the scale of urban park green space,and quantifies the scale relationship in the urban park green space structure.The fractal rules and problems of scale structure of urban park green space.Then from the perspective of the comprehensive benefits of urban park greenland,the performance verification of urban park greenbelt is evaluated,and compared with the results of fractal analysis,it is proved that the quantitative assessment of the scale structure of urban park greenland can be made by fractal method.On this basis,based on the combination of fractal efficiency and comprehensive benefits,this paper proposes an optimization guideline and specific operation method for the rational scale hierarchy of urban park green space based on the fractal method.First,by combing the relevant theories at home and abroad,this paper selects the Zipf fractal dimension in the fractal dimension and the difference degree based on the information entropy as the calculation index to quantify the characteristics of the scale structure of urban park green space.Secondly,this paper selects the central urban area of 12 cities in China as the case study area through the three principles of self-organized city,urbanization degree,commonality and individuality of the city,and makes a study on the scale distribution and size distribution of urban park green space Fractal dimension calculation,and using the degree of equilibrium and the degree of discrepancy were analyzed.Through comparative analysis of cases,the preliminary judgment of the superiority and inferiority of 12 city scale structures and the preliminary laws of large,medium and small-scale distribution are obtained.At the same time,it is found through correlation that Zipf fractal dimension and the degree of difference are relatively consistent Relationship.Thirdly,based on the above calculation results,we analyze and summarize the important characteristics and characterization issues concerning the complexity,structural hierarchy and distribution regularity of urban park green space systems.Furthermore,the influencing factors behind these problems and laws are further analyzed,including three points: urban physical and geographical conditions,urban spatial structure and construction land conditions,and urban historical and humanistic conditions.Fourthly,the evaluation system based on the comprehensive benefit of urban green space is constructed by selecting the common evaluation indexes of ecological,economic and social benefits,and the evaluation results are obtained,and the results of the evaluation are compared with the fractal values.It is concluded that under the same amount of green space,the comprehensive benefits of urban park green space with good scale class fractal structure are also superior.Finally,on the basis of the above research,taking the urban park green land in the Lanzhou City Master Plan as a practical case,through the fractal tools,comparative analysis and comprehensive evaluation of the planning and status quo of the urban park green space proves that the fractal theory is introduced into the city park.Greenland planning evaluation has practical value.Then the rational structure of park green space scale distribution is constructed by the ideal Zipf model and ideal fractal dimension,and the scientific optimization operation method of urban park green space scale structure based on fractal theory is proposed.In conclusion,the study of urban park green space through the fractal theory proves that the urban park green space is a system with complex fractal structure.It provides new ideas and methods for the quantitative evaluation of urban park green space scale structure,and explores the scale distribution of urban park green space scale.The reasonable structure has made a useful exploration for the scientific planning and reasonable layout of urban park green space,and has certain theoretical and practical values.