关键词: 高斯两步移动搜索法, 绿地可达性, 沈阳市

Abstract: Ratio of green space area and per capita green space are often used to measure the greening degree of cities in urban planning. Such indices can reflect the general characteristics of urban green space but fail to reveal the actual situation of resources allocation. Previous studies suggest that evaluating green space accessibility is a feasible way to solve the problem. However, the current methods of green space accessibility analysis have paid little attention to supply and demand relationship between green space and residents as well as the carrying capacity of green spaces, which made these methods less useful in practice. In this study, the Gaussian based 2-step floating catchment area (2SFCA) method, which can overcome these drawbacks, was employed to analyze the green space accessibility of Shenyang. The paper discusses a new method for green space accessibility assessment. Meanwhile, it offers an in-depth knowledge of green space of Shenyang. The spatial pattern of green space accessibility of Shenyang shows a clear declining trend from north to south and from east to west. Four high-value centers and three low-value areas can be recognized. The high-value areas are mainly located in the periphery of the core urban area, and the low-value areas are mainly distributed in the far southern and western suburb of Shenyang. It is also found that the spatial pattern of green space accessibility shows strong polarization characteristics, and more than 70% of the streets have lower green space accessibility than the average level around the city, while only a few streets exhibit higher accessibility. This phenomenon is attributed to the spatial mismatch between green space and population. Four recommendations are made for promoting the equal provision of green space services: (1) Enhance the quantity and quality of the green spaces in the core urban area. (2) Make scientific planning for the new development areas, to achieve the goal of equal accessibility of green space service and realize a coordinated development of population, transport, and green space. (3) Emphasize the people-oriented principle, enhance the aesthetics value of green space, public participation in their development and accessibility by considering the comments and suggestions from the public. (4) Stress the construction of green belt along the river, large public green space and roadside green space, create a balanced layout of small green spaces and improve the connection between these green spaces, to build a green space network comprised of points, belts and areas. The paper also discusses the drawbacks and improvements of the Gaussian based 2SFCA method. First, it is unable to create an accessibility surface because the result is expressed as values at the center points of streets and these values are discrete. Kriging spatial interpolation can be used to address this issue. Second, in this study size is used as the single indicator for the service ability of each green space, but factors determining the attractiveness of individual green space are much more complex and therefore more indicators need to be included in future studies. Third, the user group of green space is generalized in this model without considering the differences in needs, preference, and behavior between population groups. Green space accessibility for different age, ethnic, income and occupation groups should be assessed separately in future studies. Overall, the Gaussian based 2SFCA method is an effective method for evaluating the accessibility of the urban green space in Shenyang.

Key words: Gaussian based 2-step floating catchment area(2SFCA) method, green space accessibility, Shenyang