Spatial planning for urban ventilation corridors by urban climatology

Ventilation corridors in cities can decrease air pollution and alleviate heat island problems but there remains a need to fully assess their effectiveness.Few urban managers have been able to take city-scale approaches to the construction of urban ventilation corridors.This study aimed to introduced the Ventilation Corridor Planning(VCP)model,which is a multi-criteria evaluation method combined with a geographical information system(GIS)to determine where the ventilated environment is most appropriate.Specifically,the VCP model took Bozhou,China as the research object and contained two scales,including mesoscale and local scale.In mesoscale scale,we got three outputs to build urban ventilation corridors,including 1)background wind environment,2)ventilation potential,3)heat island intensity.In local scale,we used traditional computational fluid dynamics(CFD)model to verify the impact of VCP criteria.The results revealed that compared with the traditional CFD model,the proposed VCP model has advantages in establishing a comprehensive evaluation standard.In addition,the application of VCP model in macro and micro also enhances the efficiency of ventilation corridor construction.Overall,this study introduced a effective modeling method to urban ventilation corridors planning,and provide a way to study the urban climate.

Assessment of Urban Climate Environment and Configuration of Ventilation Corridor:A Refined Study in Xi'an

Integrating urban spatial landscape(USL) parameters into refined climate environment assessment is important. By taking the central urban area(CUA) of Xi’an, China as an example, this study develops an evaluation method based on Urban Climatic Map(UCMap) technology. We define surface urban heat island intensity(SUHI) and surface ventilation potential coefficient(VPC), which can effectively reflect local urban climate. Based on SUHI and VPC,we analyze the influences of seven typical USL metrics including building height(BH), building density(BD), floor area ratio(FAR), sky view factor(SVF), frontal area index(FAI), surface roughness length(RL), and vegetation cover(VC). Then, we construct a comprehensive evaluation model and create an urban climate zoning map on a 100-m resolution. The climate optimization on the map is performed for configuration of possible ventilation corridors and identification of associated control indicators. The results show that the main factors affecting SUHI in the CUA of Xi’an are VC and BD, which explain 87.9% of the variation in SUHI, while VPC explains 50% of the variation in SUHI. The main factors affecting VPC are BH, FAR, FAI, and RL, all of which contribute to more than 95% of the variation in VPC. The evaluation model constructed by SUHI, VPC, and VC can divide the CUA into climate resource spaces, climate preservation spaces, climate sensitive spaces, and climate restoration spaces. On this basis, a ventilation corridor network of 3 level-1 corridors(each over 500 m wide), 6 level-2 corridors(each over 500 m wide) and 13 level-3 corridors(each over 50 m wide) is established. Meanwhile, the main quantitative control indicators selected from the USL metrics are proved to be capable of ensuring smooth implementation of the planned corridors at different levels.