| The rain garden as one of the effective measures of sponge city,the main construction purposes as rainwater purification and storage,as global climate change and urban heat island effect intensifies,urban green space to alleviate urban heat island effect,improve the function of the outdoor thermal comfort is taken seriously more and more,also have a lot of research in recent years the city microclimate in a paper published,As a part of urban green space,rainwater garden also bears the responsibility of optimizing microclimate environment.This study takes rain garden as the research object,explores the microclimate effect of rain garden,and provides reference for the design of microclimate optimization of rain garden.This study for rain garden and its difference with common green space was analyzed,and based on the micro climate influence factors and influence mechanism analyses the rain garden and the difference between ordinary green space will form micro climate differences,finally determine the underlying surface as variables,and is verified by the measured and ENVI-met software simulation rain garden with ordinary green space differences between the characteristics of the micro climate.The underlying surface,topography,area,soil moisture,location,water and vegetation of the rain garden were determined as the research variables,and the influence degree and influence mechanism of each variable on the microclimate of the rain garden were analyzed through measurement and simulation.Research on the construction of the rain garden of chengdu,finally chose the most up to the standard of the measured holy light park and Gui Xi ecological park as the measured object,based on the research on the construction of the measured object of rain garden and ordinary green space into the choice of measuring points,two were analyzed by using of the measured points micro climate park in different underlying surface thickness of rainwater garden with ordinary green micro climate differences,The average daily temperature,relative humidity and black bulb temperature of rain garden in Shengdeng Park are lower than those of common green space.In guixi Ecological Park,the daily mean air temperature and black bulb temperature of the rain garden were higher than those of the common green space on sunny days,and the daily mean air temperature and black bulb temperature of the rain garden were lower than those of the common green space.This research use ENVI-met software Settings of the rain garden underlying surface profile is studied,and this paper determined the rain garden was analyzed through modeling simulation of air temperature,relative humidity of the research variables,the influence of wind velocity and PMV value,thus it is concluded that:(1)the rain garden area and the water two variables to the influence degree of the micro climate,The influence of area change on temperature,relative humidity and PMV is greater than that of wind speed,and the influence of water on relative humidity and PMV value is greater.(2)In the simulation group of this study,the rain garden with thicker underlying surface,larger area,higher soil moisture,more obvious cooling and humidification effect,and lower PMV value;The larger the concave terrain,the lower the temperature,relative humidity and PMV values of the rain garden simulation group.The road temperature around the rain garden is higher than the temperature inside the rain garden,but the relative humidity is lower,but the PMV value is lower.The rain garden with tree,shrub and grass vegetation type can reduce temperature,improve relative humidity and wind speed,but the overall PMV value is higher,while the rain garden with herb vegetation type has lower PMV value,which is more conducive to thermal comfort.Through software simulation,the microclimate difference between rain garden and ordinary green space is compared under the three variables of soil moisture,water and vegetation type,and it is concluded that:(1)when the soil moisture change,rain garden group simulation of the change of air temperature,relative humidity and PMV value than ordinary green space simulation group of small variations in amplitude,and presents with the loss of the soil moisture,the rain garden simulation set temperature and the range of the PMV value are smaller than the ordinary green space simulation group rise trend;(2)In the simulation group of water accumulation variables,the temperature,relative humidity,wind speed and PMV values of the rain garden simulation group were lower than those of the ordinary green space simulation group,and the differences of temperature,relative humidity and PMV values between the rain garden and the ordinary green space simulation group were greater than those between the two groups with water accumulation.The difference of temperature and PMV values between the two groups was smaller in the rain garden simulation group than in the common green space simulation group,and the difference of relative humidity was larger than that in the common green space simulation group,and the difference of wind speed was small.(3)In the vegetation variable simulation group,under the same vegetation type,the difference of wind speed and PMV between rain garden and ordinary green space is small,while the difference of temperature and relative humidity is relatively obvious.The temperature and PMV of rain garden simulation group are lower than that of ordinary green space simulation group.When the vegetation type was herbaceous,the relative humidity of the rain garden simulation group was lower than that of the common green space simulation group,and when the vegetation type was shrub herb and tree shrub,the relative humidity of the rain garden simulation group was higher than that of the common green space simulation group.Finally,based on the measured and simulated results,a rain garden design strategy based on microclimate optimization was proposed in four aspects of rain garden area,terrain,underlying surface and plant design.The microclimate optimization was incorporated into the design process of rain garden,providing a theoretical basis for improving the thermal comfort of urban green space and rain garden. |
