基于互联网地图服务和Ga2SFCA的天津市中心城区公园绿地可达性

Accessibility of urban green space in downtown area of Tianjin based on internet map service and Gaussian 2-step floating catchment area method

基于互联网地图服务数据,采用高斯型两步移动搜寻法(Ga2SFCA),以居住区为评价单元,通过设置4个不同的搜索半径对天津市中心城区的公园绿地可达性进行了测算及敏感性分析,探讨公园绿地可达性的变化规律,同时采用空间自相关分析探讨了街道尺度绿地公园可达性和人口密度的关系.结果表明:天津市中心城区公园绿地整体可达性水平较低,14.5%的居民无法在15 min内抵达公园绿地;公园绿地空间布局不均衡,西南部西青区和南开区绿地公园面积和人均面积远高于其他区域,不同居住小区间可达性差别较大;随着搜索半径的增大,公园绿地的可达性有改善的趋势,将公园绿地的服务半径由15 min增大到30 min后,可达性为一般及以上的居民人口比例由30.69%提升至65.34%;搜索半径越大,可达性值域的变化幅度会变小,公园绿地服务的可达性差异降低;高人口密度-高可达性聚类和低人口密度-高可达性聚类区域主要分布在中心城区南部的12个街道,高人口密度-低可达性和低人口密度-低可达性聚类区域主要分布在中心中部北部的21个街道.

The spatial accessibility and its variation rules and sensitivity of urban green space in downtown area of Tianjin were calculated and analyzed with four different searching radius using resident areas as a basic unit by Gaussian two-step floating catchment area method(Ga2SFCA)based on Internet map service,and the relationship between accessibility and population density of street-scale was explored using spatial autocorrelation analysis.The results show that the spatial accessibility of public green space in downtown area of Tianjin central districts is poor,and14.5%of residents cannot reach the park green space with-in 15 min.The spatial distribution of urban green space is unbalanced,the area and per capita area of greenbelt parks in Xiqing District and Nankai District in southwestern are much higher than that in other areas,and accessibility difference of different resi-dential areas varies greatly.The accessibility of urban green spaces tends to be better as the search radius increases.The proportion of residents with accessibility of ordinary and above can be increased from 30.69%to 65.34%by increasing the service radius from 15 min to 30 min.The change range of accessibility becomes smaller with the larger search radius,and the difference in the acces-sibility of urban green space services may become smaller.High-high and low-high clustering areas are distributed in 12 streets in the south of the downtown,high-low and low-low clustering areas are distributed in 21 streets in the north of the downtown.