广州市主城区风道特征与通风效能评估

Characteristics of ventilation channel and ventilation efficiency assessment:A case study of main built-up area in Guangzhou

本文以广州市主城区为研究对象,简化城市建筑群后绘制出无建筑区域的中心线,进而识别风道。利用2016年逐时风向风速数据,基于GIS提出了度量风道物理、热力属性的指标,据此分析风道特征,并对通风效能进行了评估。研究表明:(1)在40 m分辨率下识别出潜在风道中心线共有2451条,相互组合后达到风道标准的有142条,总通风面积为96.49 km^(2),占研究区的21.59%。(2)以珠江新城为中心,研究区潜在通风网络呈现略向东北方向倾斜的密—疏—密的圈层特征;老城区通风面积有限,区际间风道的宽高比差异较大,珠江新城最低(6.54),海珠湿地最高(74.43);主城区外围区域的绿地与水域占风道通风面积比重超过90%。(3)由走向效能空间分布格局的相似性,可分为春、夏和秋冬3个模式;依据走向效能得分的季节变化规律,划分出常年风道、季节风道和沟通风道3类。各季节通风效能评估优劣关系为:秋>冬>春>夏。(4)研究区内高架桥对阻滞度的贡献是行道树的2倍以上,阻滞度最大值为4.70 m^(3)/m^(2),阻滞程度较高的区域大部集中分布在研究区西侧,特别是三元里周边密集的立交桥群区域。

This paper attempts to explore the feature and efficiency of the ventilation channel in the main built-up area of Guangzhou, one of the four first-tier cities in China. Building groups were simplified and then the centerlines of open areas were sketched out, and finally proceeded to the identification of the ventilation channels. Data of hourly wind direction and velocity of the year 2016 were used. Indicators based on GIS for measuring the physical and thermal properties of ventilation channels were proposed, which facilitate the analysis of the characteristics of the ventilation channels and the evaluation of their efficiency. The results show that:(1) There are 2451 potential ventilation channel centerlines at a 40-m resolution,when composed, 142 meet the standard of ventilation channel. The total ventilation area reached 96.49 km^(2), accounting for 21.59% of the study area.(2) Centering around the Pearl River New Town, the potential ventilation network in the study area presents dense-sparsedense concentric characteristics, and inclines slightly to the northeast direction. The ventilation area of the old town is relatively limited. The width-height ratio of ventilation channel in the Pearl River New Town is 6.54 while in wetland area it reaches the highest to 74.43, illustrating that width-height ratio among different districts varies greatly. Green lands and waters cover more than 90% of the ventilation area of the peripheral region outside the main urban area.(3)According to the similarity in spatial distribution of direction efficiency, there exist three patterns: spring, summer and autumn/winter. In line with the seasonal variation rule of efficiency, three categories of ventilation channel are classified: perennial paths, seasonal paths,and communication paths. The result of seasonal ventilation efficiency assessment shows that autumn outperforms winter which outperforms spring which outperforms summer(autumn >winter > spring > summer).(4) Regarding retardation degree, the contribution of overpassing bridge is two times and ever higher than that of street trees. The maximum retardation in the study area is 4.70 m^(3)/m^(2) and most of the high retardation values concentrated west of the study area, especially around Sanyuanli where high-density overpassing bridges exist.