| The continuous warming of the global climate has led to frequent thermal anomalies,which have seriously endangered the physical and mental health of residents.The planning and design of landscape architecture based on the perspective of a healthy city,and the discussion of the mechanism of green space to mitigate high temperature health risks,are important topics for the sustainable development of urban ecosystems.Currently,there are many theoretical and practical literature on urban thermal environment research,but less attention has been paid to spatial assessment of thermal environment and physical and mental health hazards.Research on green space optimization from the perspective of public health is relatively lacking.Therefore,reasonable assessment and prediction of urban thermal environment and its health risks,optimizing and improving the layout of urban green space,and strengthening the ability to adapt to climate change in key sensitive areas and key areas are currently important scientific and practical issues.This study is based on Landsat remote sensing images,meteorological stations,questionnaires,disease data,and high-precision maps,as well as modeling techniques such as Arc GIS,MATLAB,ENVI,and SPSS,to analyze the spatiotemporal dynamic evolution process and influencing factors of the thermal environment in the six ring roads of Beijing from 1991 to2021.At the same time,based on the MGWR model,it further quantitatively studies the spatial scale differences between the thermal environment and various influencing factors.Establish a public health evaluation index system to explore the spatiotemporal pattern characteristics and changes of the impact of thermal environment on public health in the sixth ring road of Beijing in the past 30 years.Finally,a comprehensive risk assessment system for thermal environment health is constructed,and a green space layout model is proposed to effectively improve the public health hazards of urban thermal environment.The main research conclusions are as follows:(1)The thermal environment changes in Beijing in the past 30 years have periodic characteristics.From 1991 to 2021,sub low temperature areas and low temperature areas gathered from large patches outside the third ring road in the east and west urban areas,gradually showing small patches fragmented until almost disappeared,with the proportion of sub low temperature areas decreasing from 73.07% in 1991 to 0.08% in 2021;The intermediate temperature zone spreads radioactivity from the central urban area to the surrounding areas to the entire region;The sub high temperature zone shows a patchy outward development of the East Third Ring Road and the Southwest Third Ring Road,and a large area gathers in the southeast urban area,rising from 0.43% in 1991 to 53.82% in 2021;The high-temperature area mainly presents a scattered distribution of small patches within the South Third Ring Road.(2)Vegetation coverage(FVC),normalized vegetation index(NDVI),improved normalized water body index(MNDWI),building height(BH),building density(BD),plot ratio(FAR),and road network density(RND)are significantly correlated with the thermal environment of Beijing,reaching a good interpretation level.The results of the MGWR model indicate that the impact of different drivers has significant spatial heterogeneity.Compared to the GWR model,the AICc value and the sum of squares of the residuals of the MGWR model are significantly reduced,and the goodness of fit is significantly improved,making it more suitable for relevant research on the urban thermal environment.(3)The spatiotemporal evolution of the impact of Beijing’s thermal environment on public health from 1991 to 2021 shows that the level of public health impact has increased from 1-3 to3-5.The spatial distribution is characterized by a rapid decline in the low impact areas,a divergent expansion of the medium impact areas from the urban center to the outer ring and gradually interconnecting into large patches,and a trend of agglomeration of high impact areas within the third ring road of the city.Introducing the landscape pattern method,selecting the patch density index(PD),connectivity index(CONNECT),diversity index(SHDI),and contagion index(CONTAG)to quantitatively analyze the changes and differentiation characteristics of public health landscape patterns,it was found that in the past 30 years,Beijing’s urban landscape patches have gradually broken,connectivity has decreased,and ecosystem functional links have broken.(4)A comprehensive risk assessment system for thermal environmental health is constructed based on four indicators: potential cooling factor,urban ventilation potential,heat load,and public health.A comprehensive high-temperature health early warning map is generated and divided into 6 categories,including 1-6.The research shows that the 5-6 levels with relatively severe high temperature health warnings are mainly distributed in the central urban areas within the Second Ring Road to the Fourth Ring Road,with a compact patch group layout and a trend of extending to the surrounding areas,indicating that the healthy climate environment within the Sixth Ring Road in Beijing will further deteriorate,and corresponding countermeasures to adapt to climate change are needed;Level 3-4 is distributed radially around the periphery of Level 5-6 from the city center to the surrounding area,and Level 1-2 is distributed in the outer edge of the Fourth Ring Road and the outer suburbs.(5)The study selected 20 existing green space nodes for renovation,and added 28 new green space nodes to carry out "embroidered" micro update.The "four horizontal and four vertical" network corridor structure layout is connected in series with landscape nodes to break the accumulation of large patches of heat islands;Create 8 country parks based on current natural resources,form a spatial pattern where 9 wedge-shaped green spaces combine with 8suburban parks outside the city,and strengthen the potential for urban ventilation;Create a "three ring" structure of the Old City Heritage Park Ring,one urban park ring,and two rural park rings to improve the connectivity between the urban area and suburban green space.Finally,a green spatial layout structure combining "points,corridors,wedges,and rings" will be formed to ensure the safety of residents’ daily activities and improve their health level. |
