The Study Of The Green Space Layout And Accessibility In The Parks In Chinese Big Cities Based On Fractal Theory

The green space in a city park is an element of a green space system of a city which is closely related to people’s life in the city.Only with the rational layout of the green space in city parks,the service efficiency of the parks could be increased to the full and the building level of the green space a city could be improved further.In the beginning of city building in China,it was not necessary to consider whether the built green space could have good service functions or whether their service areas overlapped or not.However,when there are certain numbers of landscape green spaces in a city,people began to pay more attention to the quality of the green space.Thus,it will become quite important to lay out the green space scientifically,rationally and fairly.It is impossible to lay out the green spaces of parks reasonably and fairly based on the present actuality indices such as green space rate,per capita green spaces in parks,etc.as well as the direct experience of any planner.Therefore,new theories and technologies are required to promote the evaluation mechanism for the existing green spaces in parks,to evolve and improve existing planning theories and techniques.Fractal Theory is a quite popular and active theory and a new discipline at present.As a leading theory to study the self-similarity of a complicated system,the universality and philosophical meaning of Fractal Theory have been widely accepted.Fractal structure has a special characteristic to ensure optimum efficiency.If a city has its fractal structure,that is,it has ability and potential to continuously optimize the structure of the city,it could make the structure of the city develop into its optimum situation.Therefore,in this thesis,Fractal Theory will be applied to study the park green spaces in a city.Firstly,in this thesis,nine big cities in China(including Beijing,Shanghai,Shenyang,Nanjing,Hefei,Chengdu,Chongqing,Wuhan and Xi’an)are selected as the cases to study.The green space in the cities was analyzed with the index system of appraisal adopted by Ministry of Housing and Urban-Rural Development of the People’s Republic of China,which indicates that the present index system couldn’t appraise whether the layout of the green space is sensible or not.Secondly,based on the principles and applications of Fractal Theory,and combined with the coupling of fractal and the study of the green space in parks as well as the relevance between fractal dimension and the layout of the green space in parks,gridding dimension,semi-diameter dimension and Zipf dimension are selected as basis to study how to layout the green space in parks sensibly.Meanwhile,based on the basic computation model of fractal dimensions,the computation model of the three kinds of fractal dimensions of the park green space is built.Thirdly,contrasting and evaluating the calculation results of the three dimensions of the nine cities,the meaning of space meaning symbolized by the three dimensions will be summarized,and the characteristics of the layout of park green space in Chinese big cities as well as comprehensive appraisal will be extracted.Then,by contrasting the results of this appraisal with those from the evaluation with the present indices,Fractal Theory will be proved that it could remedy the limits of the present indices used to appraise the green space in parks.Finally,based on the three indices—the filling ratio and uniformity of distribution of the green space in a city from gridding dimension,the vergence of the park green space from the center to the outskirts of a city got from semi-diameter dimension and the ratio of the scales of the park green space got from the Zipf dimension,an appraisal method for the sensible layout of park green space in a city is worked out,which could be adopted to complement the evaluation system of park green space in a city.Meanwhile,the problems it could solve,its advantages over the other evaluation methods of space layout,and its practical meaning in planning will be illuminated.Park green space is not only one of the important elements in the construction land of a city but also one of the important criteria of a livable city.Rational layout of park green spaces in a city can function to protect the ecosystem of the city and to induce the city to develop well.Furthermore,it also can efficiently supply balanced,comfortable green leisure space for the habitants in the city.The thesis is in the hope that,with Fractal Theory to study how to appraise the layout of park green space,it would supply a new way to think and a new method to the study how to lay out park green space in a city sensibly.