热环境内不同类型水体降温效应的时空变化及景观影响

Spatiotemporal Variation of Water Body Cooling Effect with Landscape Type on the Urban Thermal Environment

探索不同类型水体降温效应的时空变化特征,可为缓解城市热环境问题提供理论支持。基于Landsat遥感数据,以福州市2002-2020年典型湖泊、河流为例,利用缓冲分析法定量描述不同类型水体降温效应的时空变化;对湖泊采用网格分析法、河流采用等距离分段分析法,探讨了水体周边景观特征对不同类型水体降温效应的影响。结果表明:(1)福州市中心城区热环境问题加剧,水体成为环境内部的主要“冷源”;(2)城市河流比城市湖泊更具备“冷岛”潜力;(3)湖泊的降温效应受周边植被占比、建设用地占比影响较大,在湖泊周边120 m内,当绿地面积占比>34%时,建设用地面积占比<48%,湖泊与绿地的综合降温效果最好;(4)河流的降温效应受周边植被占比、建设用地占比及裸地占比影响较大,在河流周边180 m内,当绿地面积占比>44%时,建议建设用地面积占比<31%,河流可产生最大的降温效应。在未来城市规划中,水体周边景观的合理布设将有助于水体发挥最佳降温效果。

Exploring the spatial and temporal variation of the cooling effect of different types of water bodies can provide theoretical support for mitigating the heat island effect in urban areas.In this study,typical lakes and rivers in Fuzhou City were selected for a case study,and we quantitatively analyzed spa-tial and temporal variations of the cooling effect of different types of water bodies in Fuzhou City from 2002 to 2020 using the buffer analysis method.Further,we explored the influence of landscaping around the water bodies on the cooling effect using grid analysis for lakes and isometric segmentation for rivers.The types of water bodies in the study area included a typical artificial lake(Xihu Lake),reservoirs(Dengyun and Bayi),and rivers(Minjiang,Wulong and the Fuzhou section of Dazhangxi).Surface tem-peratures and land cover types for the study area were obtained from Landsat remote sensing data collect-ed on July 5 of 2002 and 2008,August 4 of 2013 and July 22 of 2020.The landscape types in the study ar-ea consisted of water,vegetation,construction and bare land.Results showed:(1)The heat island effect in downtown Fuzhou City has intensified from 2002 to 2020,and the water bodies have become the primary source of cooling.(2)Urban rivers displayed higher potential for cooling than urban lakes.(3)The cool-ing effect of the lakes was markedly affected by the proportions of surrounding vegetation and construc-tion land.When the proportion of green space was above 34%and that of construction land below 48%within 120 m of the lakes,the combined cooling effect of the lake-green area was best.(4)The cooling ef-fect of the rivers was influenced by the proportions of surrounding vegetation,construction land and bare land.When the proportion of green land was above 44%and that of construction land below 31%within 180 m of the river,the cooling effect of the river-green area was best.Using these results to guide land-scape design around water bodies can maximize the cooling effect on urban areas.