基于MSPA的街区蓝绿基础设施格局及其热缓解特征

Characteristics of blue-green infrastructure and its relationship with thermal environment in blocks based on morphological spatial pattern analysis(MSPA)

城市绿蓝基础设施在解决城市热环境、提升热舒适性以适应气候变化等方面具有重要作用。本研究基于北京市三山五园地区高分辨率影像,通过形态学空间格局分析(MSPA)量化城市蓝绿基础设施(GBI)格局特征,统计分析街区GBI组成结构与街区地表温度的相关关系,并探究GBI热缓解能力与影响因素。结果表明:三山五园地区GBI面积占比为60.61%,地表平均温度(T_(m))与GBI面积比呈显著负相关,且与树木占比的相关性大于水体和草地,与核心区占比的相关性依次大于孔隙区、边缘区、环路区、桥接区、支线区;GBI空间形态格局显著影响其热缓解特征;在GBI核心区面积占比大于10%的街区,T_(m)与核心区和孔隙区面积占比呈显著负相关,而与树木、草地和水体等类型面积占比无相关性;在核心区占比介于1%~10%的街区,T_(m)与树木以及环路区、桥接区和支线区面积占比均呈显著负相关;核心区占比小于1%的街区,T_(m)仅与边缘区面积占比呈显著负相关;未来街区GBI规划设计除考虑绿地覆被类型外,应紧密结合街区GBI布局形态特征,可采用扩大规模(围绕现有GBI斑块增加外围边缘区宽度)、提升连通性(连接现有GBI斑块构建蓝绿廊道)、优化活动场地配比(适度增加核心区内部活动场地)等适应性方法,形成街区基于自然的热缓解解决方案。研究结果可以增进对城市街区蓝绿基础设施格局与热缓解特征关系的理解,为街区尺度缓解热岛效应、提高热舒适度提供参考。

Urban green-blue infrastructure(GBI)in blocks plays an important role in adapting to climate change by solving urban thermal environment and improving thermal comfort.Based on high resolution images of Three Hills and Five Gardens Area in Beijing,morphological spatial pattern analysis(MSPA)was used to quantify the pattern of urban GBI.GBI types included branch,bridge,core,edge,islet,loop,and perforation.We analyzed the correlation between GBI’s composition and structure and land surface temperature,and GBI’s thermal mitigation ability and its influencing factors.In Three Hills and Five Gardens Area,the area ratio of GBI was 60.61%,while the correlation between mean surface temperature(T_(m))and GBI’s area ratio was significantly negative.The correlation between T_(m)and ratio of trees was greater than that with water body or grassland.The relevance was higher between T_(m)and the ratio of core area than with perforation area,edge area,loop area,bridge area and branch area in turn.Thermal mitigation of GBI was significantly affected by its spatial pattern.In the blocks with core area ratio of GBI over 10%,T_(m)was negatively correlated with the proportion of core area and perforation area,but not with that of tree,grassland,and water.In the blocks with core area ratio of GBI between 1%and 10%,T_(m)was negatively correlated with trees occupying area,loop area,bridge area and branch area.In the blocks with core area ratio of less than 1%,T_(m)was negatively correlated with edge area.In addition to taking green space cover types into consideration,the planning and design of GBI in future blocks should be closely combined with the characteristics of GBI layout,which can be implemented by the following measures:enlarging the scale(increasing the width of peripheral edge area around existing GBI patches),enhancing connectivity(connecting existing GBI patches to construct blue-green corridor),optimizing the configuration of activity fields(appropriately increasing activity fields within the core area),in order to form the nature-based thermal mitigation solutions for blocks.The results can enhance the understanding of relationships between GBI pattern and thermal mitigation characteristics in urban blocks,and provide reference for the mitigation of heat island effect and thermal comfort improvement at urban block scale.