基于局地气候分区的广州滨水街区热岛强度研究

Local Climate Zone-based Urban Heat Island Intensity of Guangzhou Waterfront Blocks

局地气候分区(Local Climate Zone, LCZ)是近些年新兴的可量化城市形态与热岛强度关系的分析方法,可有效从中尺度分析街区形态对热环境的影响,但仍存在缺乏关注如水体等外部潜在影响因素、以固定网格划分基本分析单元等局限。利用多源数据,以街区为基础研究单元对广州市主城区进行LCZ分类,在分析各类型水体的降温效应基础上区分滨水街区与非滨水街区,并讨论街区形态与热岛强度(Urban Heat Island Intensity, UHII)的关系。结果表明:1)广州主城区街区可分为13类建筑类型LCZ(LCZ1~LCZ10),其中LCZ3(紧凑低层)、LCZ5(开敞多层)和LCZ6(开敞低层)占比最高,超强热岛区与强热岛区以低层、多层街区为主,街区热岛强度与街区开敞程度和街区平均建筑高度有密切关系;2)广州主城区水体可分为5类,3类线状水体(珠江、河流、河涌)和2类面状水体(湖泊、坑塘),线状水体的降温强度与降温距离随着宽度的变宽而增加,而面状水体则随着面积的增加而增加;3)对比滨水街区与非滨水街区,多数LCZ类型可获取不同程度的水体降温效应,其中开敞街区与高层街区(LCZ1、LCZ3.5、LCZ4.5、LCZ9)可获取相对更明显的水体降温效应,而紧凑低层的街区形态(LCZ2.5、LCZ3)会阻碍街区获取水体降温效应。以上结果可为以缓解热岛效应为目标的滨水街区形态优化相关规划提供理论支撑。

The local climate zone(LCZ) proposed in recent years can quantify the relationship between urban morphology and urban heat island strength. It can effectively analyze the impact of block morphology on the thermal environment from a mesoscale. However, there are still limitations, such as the lack of attention to external potential influencing factors as for water and the division of basic analysis units with fixed grid. This paper uses multi-sources data to classify the main urban area of Guangzhou by LCZ classification with blocks as the division unit. At the same time, it distinguishes waterfront blocks from non-waterfront blocks on the basis of analyzing the cooling effect of various types of water, and discusses the relationship of the form of the block and the Urban Heat Island Intensity(UHII). The results show that: 1) The blocks in the main urban area of Guangzhou can be divided into 13 building types LCZ(LCZ1-LCZ10), among which the highest proportions are LCZ3(compact low-rise), LCZ5(open mid-rise) and LCZ6(open low-rise). The super heat island area and the strong heat island area are mainly low-rise and mid-rise blocks. The UHII of the block is closely related to the openness of the block and the average building height of the block;2) The water in the main urban area of Guangzhou can be divided into five types, with three types of linear water(the Pearl River, rivers, and stream) and two types of planar water(lake and pond). The cooling intensity and cooling distance of linear water increase as the width becomes wider, while that of the planar water increase as the area increases;3) Comparing waterfront blocks with non-waterfront blocks, most LCZ types can obtain water cooling effect with different levels. Among them, open blocks and high-rise blocks(LCZ1, LCZ3.5, LCZ4.5, LCZ9) can obtain a relatively more obvious water cooling, while the compact low-rise block form(LCZ2.5, LCZ3) will hinder the block from obtaining the water cooling. The above results can provide theoretical support for the planning of waterfront block morphology optimization with the goal of mitigating the heat island effect.