| Human health effects under global urbanization and climate warming have become important issues,among which health hazards caused by urban thermal environment are widely concerned,especially in mega-cities with severe urban heat island and dense population.Therefore,based on the perspective of landscape garden planning and design and healthy city design,it is an important topic for sustainable urban development to explore the climate regulation role and ecological health effects of urban green space system to mitigate the risk of high temperature exposure of future urban residents.At present,scholars focus on the thresholds of urban green space cooling effects and their correlation with public health,and landscape design work under the public health perspective is relatively insufficient.As a result,effective green space system layout and green infrastructure design to mitigate the health risk of high temperature exposure to urban residents through landscape planning and design methods is a critical current scientific and practical issue.Based on the World Clim future climate dataset,actual data from meteorological stations,Landsat satellite imagery,high precision maps,and statistical yearbook data,this study uses Arc GIS spatial analysis technology,WRF/UCM climate simulation technology,remote sensing inversion technology,and environmental health risk assessment models to analyze the current and future summer high temperature spatial pattern characteristics within the Sixth Ring Road of Beijing,and combine The relative risk of high temperature exposure in the study area was quantitatively evaluated by combining urban residents’ walking and bicycle commuting,and the areas with higher hazard levels of high temperature exposure were identified.Combining the spatial cooling and health effects of Beijing’s current green spaces and water bodies,the scope of optimization of urban healthy spaces is analyzed to provide decision reference for the optimization strategies of green nodes,corridors and wedge-shaped green spaces as well as the design of green infrastructure demonstration areas,and finally to develop optimization strategies for green space planning and design that effectively mitigate urban high-temperature exposure hazards.The findings of the study can be used for the identification of urban high temperature environmental exposure risk spaces to provide reference for healthy city planning and promote sustainable urban development.The main findings of this study are as follows.(1)The spatial and temporal distribution characteristics of the current situation and urban high temperature environment in 2021-2040,as well as the comparative analysis of typical high temperature days,extreme high temperature days and the spatial pattern of warming in future scenarios show that: the high level temperature is concentrated in the center of the city and distributed in patches in the periphery of the city,and there are more high level temperature patches in the southern urban area than in the northern urban area;the high temperature space under all three SSP pathways is concentrated in the fourth ring of the central city,and radiating from the central city to the outer ring,and the lower temperature areas are distributed in the fifth to sixth rings.Influenced by the future development pattern,with the development of urban population,socio-economics and education,the urban high-temperature environment is on a rising trend,and the threat posed by high-temperature hazards is further intensified,and the warming range is mainly concentrated in the fifth to sixth rings.(2)The results of the variability of future high temperature exposure risk under three social sharing economy pathways of SSP1-2.6,SSP3-7.0,and SSP5-8.5 show that 66.57% and 50.07%of the area of Beijing’s Sixth Ring Road for walking and bicycle commuting in 2021-2040 are in high temperature exposure risk areas(low risk,medium risk,and high risk areas),respectively,and the overall exposure risk The range is concentrated,with higher doses of high temperature exposure in the periphery of the city and lower doses of high temperature exposure in the center of the city;spatially,the medium and high risk areas are radiating along the metro line,and the minimum risk area and low risk area are star-shaped radiating along the metro line.The future temperature increase will lead to an increase in the area of high risk areas for high temperature exposure in the fifth to sixth rings of Beijing,especially in the SSP1-2.6 and SSP5-8.5 pathways;the administrative districts with more serious health hazards from high temperature exposure are Chaoyang District,Haidian District,Shunyi District,Daxing District,and Changping District.(3)Considering the "time-activity" pattern of the population,the current situation of urban infrastructure and socio-economic development,and combining the comprehensive health index and the influencing factors of urban heat pattern,the health risk warning map of urban heat environment is constructed,and the health warning within the sixth ring of Beijing is divided into10 categories.Level 0 warnings are mainly located in the fifth to sixth rings,expanding from the city center to the periphery;level 1-2 more serious areas are located around the level 0 areas;level3-5 areas are radially distributed from the city center to the sixth ring;level 6-8 low-level health warning areas are concentrated within the fifth ring and are distributed in linear patches.Based on the characteristics of the spatial pattern of health impact levels,three types of planning and renovation zones of high health risk,high value and low sensitivity are identified,and on the basis of health hazard identification,corresponding planning suggestions and renovation strategies are proposed to provide reference for the optimization of the green space system.(4)Based on the vector data analysis of green areas and water bodies in Beijing,it was found that the current area of green areas and water bodies within the 6th Ring Road of Beijing is 236.26km2 and 54.90 km2,accounting for 9.45% and 2.20% of the total area,respectively.According to the scope of health effect and cooling effect,buffer zone analysis was conducted for the range within 500 m of green areas and 600 m of water bodies,and combined with different park green space types,superimposed analysis was conducted to generate a comprehensive urban health effect pattern.The existing health-optimized spaces in the study area are mainly distributed within the fifth to sixth rings,and the spatial distribution is uneven within the fourth ring,which cannot achieve effective mitigation of urban high temperature environment.(5)The study selects 20 existing park nodes for renovation,while adding 37 new green space nodes.The nodes are connected to a corridor network of "four horizontal and four vertical",linking the major urban parks with green nodes and water systems to form an urban network ecological structure,expanding the scope of green space and water bodies to reduce the health hazards of high temperature exposure.Areas rich in existing natural resources are selected to integrate village space and landscape resources to create eight country parks.Relying on the practice project,12 current green areas are selected to build cool stations,and the types of green areas include large parks,strip gardens and small gardens.Real-time measurement points are established through the cool stations to cope with extreme high temperature and urban heat island effect brought by abnormal weather,and to change the population structure and community composition by creating native plant communities.Thus,the construction of ecological civilization and the health and safety of urban residents are guaranteed.The main points of innovation in this study are the following.(1)Based on the commuting activity patterns of residents in the urban high temperature environment,this study quantitatively investigates the dose levels of high temperature exposure generated in commuting and explores the quantitative relationship between high temperature factors and residents’ health.(2)Starting from the future 20-year planning period,we use future climate simulation data to analyze the spatial and temporal patterns of high-temperature exposure,delineate the risk areas of high-temperature exposure hazards,combine the health effects of green space to focus on the transformation of areas with serious high-temperature exposure hazards,and provide reference and decision-making basis for the optimization of urban green space system planning and layout.(3)Based on the spatial and temporal variation of high temperature exposure hazards,we identify high-risk areas and explore green space planning and design strategies to effectively mitigate high temperature exposure hazards by optimizing the green space system and the green infrastructure-the configuration of cooling stations. |
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