Research On The Construction And Management Of Urban Ventilation Corridors Based On Climate Suitability

With the advancement of urbanization,urban climate and environment problems are becoming more and more serious.The construction and control of urban ventilation corridors are of great significance for improving urban wind environment and alleviating urban heat island effect.In 2020,COVID-19 poses a huge health threat to cities.How to improve the urban air circulation through the urban ventilation corridor so as to suppress the spread of the disease in the form of aerosol transmission has been paid more and more attention.There are abundant research achievements on the construction and control of urban ventilation corridors,among which most are evaluated according to the architectural form index,but insufficient attention is paid to the ventilation efficiency of the city.In addition,the construction process is often based on a single index,lacking the elaboration and systematic combing of the construction mechanism.This research took the main urban area of Hefei as the research object.First,we analyzed the characteristics of the wind environment in the main urban area of Hefei from the perspective of urban space environment.The spatial statistical model was used to screen the relevant spatial morphological indicators that affect the urban wind environment.In addition,a comprehensive evaluation system was constructed on the basis of verifying the spatial relevance.At the same time,methods such as the least cost path and heat island inversion were used to excavate the urban ventilation corridors.Finally,The CFD model was used to verify the relevant construction indicators at the micro-scale according to the direction of the urban ventilation corridors.We also proposed early warning measures and management and control strategies for indicators to provide an important basis for improving the urban climate and improving ventilation efficiency at the urban spatial environmental level.The following conclusions showed that:The main urban area of Hefei has been in a low wind speed area in the past 10 years.The average monthly wind speed is 2.36m/s and the average annual wind speed is 2.37m/s,which is seasonal and regular in spatial distribution.The areas with higher average annual wind speed are clustered around the built-up area,while low-value areas are distributed in patches in the northern part of Luyang district and the Old city.According to statistical wind frequency results,the dominant wind direction in the past 5 years and the past 10 years has been dominated by the east-northeast wind direction(ENE),and the dominant wind direction advantage is gradually weakening.In general,the urban wind environment in Hefei is not conducive to the mitigation and improvement of urban heat island effect and urban air pollution.There exists spatial correlation between urban wind environment and urban spatial form.This study summarized the four spatial form types of land cover,functional development,building form and road traffic.According to the results of spatial statistical model,NDVI index,M-NDWI index,SVF index and Z₀ index are highly correlated with urban wind environment,and their R² are 0.75,0.61,0.83 and 0.78 respectively.Different evaluation systems were constructed by highly correlated indicators,specifically including four scenarios:ventilation potential(VCP),ventilation potential+green space(VCP+NDVI),ventilation potential+waters(VCP+M-NDWI),and ventilation potential+green space+waters(VCP+NDVI+M-NDWI).They provided conditions for the excavation of the urban ventilation corridors.According to the construction theory of urban ventilation corridors,on the basis of determining the dominant wind direction and evaluation system,we used the least cost path method to count four scenarios to construct a total of 28 urban ventilation corridors.Among them,ventilation corridors constructed with only the ventilation potential(VCP)as the evaluation system mainly pass through urban main and secondary arterial roads,and cement asphalt pavements such as urban squares.The ventilation corridors constructed with(VCP+NDVI index+M-NDWI index)as the evaluation system mainly converges in the urban natural environment such as water bodies and green spaces,and a small part also passes through artificial environments such as urban low-rise buildings.Based on remote sensing inversion method of surface temperature,we verified the benefit of constructing corridor.Specifically,we made statistics on the average surface temperature of the ventilation corridors in the four scenarios,and the results showed that the construction of urban ventilation corridors with VCP,green space and waters as carriers can ensure the optimal air volume and wind speed.In addition,this method can also combine the cooling and haze removal benefits brought by urban wind through green space and waters to produce the maximum ventilation efficiency.The planning control strategy for improving the urban wind environment mainly consists of three aspects:(1)Determination of planning control objectives:including improving urban air quality and mitigating urban heat island effects;(2)Construction of planning control methods:Including the screening of key control areas and the early warning of spatial form indicators,CFD technology is used to lock the indicators that exceed the threshold through the change of ventilation efficiency before and after index optimization.The results showed that the adoption of building morphological index optimization measures such as the reconstruction or demolition of old low-rise buildings and the optimization measures of surface coverage indexes such as green space and water bodies between buildings have the potential to improve urban ventilation efficiency;(3)Proposal of construction safeguard measures:We put forward suggestions from four aspects,including strengthening the prevention and control of air pollution and high temperature warning,strengthening departmental communication,issuing technical standards and relevant regulations for urban air duct construction,and setting up a special plan for urban air duct system.It provides a perspective for improving the comfort of urban wind environment and creating a healthy living environment.Figures[30]Tables[15]Reference[87]...