Optimization Of Urban Green Infrastructure Layout Based On The Principle Of Urban Wind Tunnel Construction

With the continuous acceleration of urbanization in China,the urban climate problem has become increasingly prominent.High-density buildings greatly weaken the circulation of fresh cold air and aggravate the heat island effect and air pollution.Urban ventilation can effectively alleviate the climate problems of the two big cities,but it is not suitable to demolishing and building large buildings to improve the ventilation conditions in high-density urban construction areas.Therefore,it is the best way to optimize the green infrastructure actively and improve the urban ventilation environment at the minimum cost.Therefore,based on the layout optimization of green infrastructure,this paper proposes Suggestions on the ventilation corridor of urban scale and the thermal circulation of meso-scale respectively,so as to realize the ventilation corridor optimization of chengdu's built-up old city.To review and summarize this article first green infrastructure in adapt to the progress of urban ventilation,as a theoretical basis.Then,with the help of Arc Gis10.2 working platform,remote sensing images were obtained by using the network open source data to build geosspace databases of existing and potential green infrastructure in the research area,and surface temperature inversion was carried out through remote sensing images to identify action space and compensate space.Select 9 main indexes that affect the ventilation potential of the city and measure the weight of each index by comprehensive weight method.By using the fishing net tool to delimit the evaluation unit and combining with the spatial measurement method to calculate the single index of each unit,the distribution characteristics of the ventilation potential in the study area are obtained through the superposition operation.Finally,with the help of the least resistance model and field measurement,7 potential air corridors and 5 mesoscale thermal circulation blocks were identified,and corresponding green infrastructure improvement strategies were proposed.The study found:Urban green infrastructure plays a unique role in climate adaptation planning.A reasonable layout of green infrastructure can not only bring wind into the city and ensure the smooth flow of urban ventilation corridors,but also promote mesoscale thermal circulation as a supplement area for cold air.The annual average still wind rate is high in Chengdu,and the polluted air is not easy to circulate.Besides,the construction density of the old city in the built-up area of Chengdu is high,and the Heat island effect of Chengdu is mainly concentrated within the old city,showing the characteristics of centralization.The green infrastructure construction in The old city of Chengdu is weak,the connectivity of each green space is not high,the network structure is broken,and the climate adaptability is low.By superposition inversion of surface temperature,land type of underlying surface and construction density,16 main action Spaces and 21 main compensation Spaces were identified in the study area.Their spatial distribution was as follows: northwest and southwest action Spaces were relatively concentrated,and compensation space points were distributed in clusters.In the north and east,the amount of action space is large and the area is small.In the second loop,the action space is the core,and several points and strip compensation space are connected and enclosed.Taking the shape index of green infrastructure(green land,cultivated land,water body),landscape index,average width of road,density of road network and density of weighted building windward area as the influencing indexes of ventilation potential,the surface ventilation potential of the study area was calculated.The potential high value and low value areas are distributed as "occupy type + nesting type",and are arranged in random phases.The high-potential ventilation area mainly relies on the distribution of roads,rivers and large areas of green space,while the low-potential ventilation area is distributed in a planar concentration within the second ring road.By integrating the factors such as the layout of green infrastructure,surface ventilation potential,function space and compensation space position,seven minimum cost paths under the prevailing winds of NNE and NW are identified and divided into four primary ventilation corridors and three secondary ventilation corridors.