GIS-based researches on urban green space on landscape gravity field with Ningbo city as an example
基于GIS的城市绿地景观引力场研究——以宁波市为例

Urban green space is an important part for the city, and a branch system of the urban ecosystem. The evaluation of the urban green space landscape is one of the important tasks about urban ecosystems. Other methods emphasize particularly the characteristics of the green space. During the construction of the eco-city, these methods do not reflect the idea of taking man as the chief role, for people are the urban main body and the end of the green space landscape which can eventually serve for and benefit people. Therefore, it is necessary to take the factor of man into account when the urban green space is evaluated. Man, the main body of the city, taken as a factor in the evaluated system on spatial distribution of the urban green space. The aim is to estimate more efficaciously the effect of the urban green space to people. The theory of field in physics has been applied, and at the same time, we put forward the conception and the valuating method of the green space landscape gravity field. The green space landscape gravity filed is the gravity value, which is formed by one unit of green space landscape or the whole green space system to urban people, or the serving capability or potential that is provided by the urban green space system to urban people. The main factors affect green space landscape gravity filed including the quality of the green space landscape, the distribution of the urban population, the actuality of the urban land use, the main traffic establishment and so on.Based on the GIS, some models must be constructed for the study of the urban green space landscape, which include the spatial distributing model of the urban resistance related to the urban land use and the type of traffic, the spatial distributing model of the urban population, the spatial distributing model of the urban public green space and the spatial distributing assessment model of green space landscape gravity filed.Taking Ningbo city as an example, based on established models, we have not only assessed the actuality of urban green space landscape gravity field, but also the validity of the green space landscape gravity field about the plan of Ningbo city. The results indicate that the green space gravity field increases for plan. The area has been improved more than one time for the public within 20 minutes.The results indicate: (1) The method reflects more efficaciously the spatial distribution character of the urban green space and has actualized the aim of the urban green space for the citizen's life, giving expression to the policy of taking man as the chief role in the urban green space. (2) A new index and assessed method have been put forward for the urban green space system. (3) The method provides a scientific basis for landscape design. (4) The landscape gravity filed may be applied for the assessment and to the study of the rationality and validity of other serving establishment in urban areas.