城市绿色开敞空间可达性研究——以南京市中心城区为例

Accessibility of urban green open space based on weighted two-step floating catchment area method:A case study of the central district of Nanjing City

城市绿色开敞空间是城市公共空间的重要组成部分,合理配置城市绿色开敞空间对城市宜居环境建设至关重要。空间可达性常用于评价公共服务设施空间布局的合理性,两步移动搜索法即是一种直观、运算简便、应用广泛的可达性计算方法,但该方法未考虑需求主体之间的差异性。本研究以南京市中心城区为例,利用手机信令数据提取需求者属性特征以及空间分布,通过分类细化需求主体改进搜索策略,改善两步移动搜索法传统研究未考虑不同群体差异性、统计数据滞后、空间尺度粗等弊端。结果表明,南京市中心城区绿色开敞空间可达性呈现出明显的空间分异特征,江南主城可达性总体比江北新区高,低值区集中在人口密度高、绿色开敞空间资源规模小的中心城区周边;不同人群的绿色开敞空间可达性总体格局相似,但在数值上老年人可达性均值是其他年龄段的14.60%,工作人群可达性均值是居住人群的86.02%,老年人作为弱势群体在享受绿色开敞空间服务中被边缘化。研究结果可为优化南京市绿色开敞空间布局提供科学依据,也可为其他公共服务设施可达性评价提供借鉴。

Urban green open space is an important part of urban public space.Reasonable allocation of urban green open space is essential for the construction of a livable urban environment.Spatial accessibility is often used to evaluate the rationality of the spatial layout of public service facilities.Two-step floating catchment area method is an intuitive,simple and widely used accessibility calculation method.However,this method does not consider the differences among demand subjects.In this study,we focus on the central district of Nanjing,extract the user attributes and spatial distribution through mobile phone signaling data.Then we subdivide the demand subjects through classification and improve the search strategy.We ameliorate the disadvantages of the traditional study of the two-step floating catchment area method that does not consider the variability of different groups,statistical data lags,and coarse spatial scales.The results show that the accessibility of green open space shows obviously spatial differentiation.The accessibility of Jiangnan area is generally higher than that of Jiangbei new area.The low value areas are concentrated around the central city with high population density and small scale of green open space resources.The overall pattern of green open space accessibility is similar for different groups.However,in terms of values,the mean accessibility of the elderly is 14.60%of that of the other age groups.The working population is 86.02%of that of the residential population.As a disadvantaged group,the elderly people are marginalized in the access to green open space services.The results can provide a scientific basis for optimizing the layout of green open space in Nanjing,and can also provide reference for the accessibility evaluation of other public service facilities.