| Rapid urbanization has led to a surge in urban population,rapid expansion of urban land use,and increased energy consumption,resulting in significant climate and environmental changes.Urban green space is considered as one of the measures with high efficiency and low cost to mitigate the heat island effect.It can not only provide cold island areas,but also radiate the cooling effect to the surrounding areas,that is,there is a spillover effect.At present,many studies have explored the cooling service characteristics of urban park green space,but there are few studies on other types of Urban green space.How to reasonably arrange the green space within the limited urban land space and balance the supply and demand of urban cooling services is still a problem worth studying.This article takes 1249 green patches in the central urban area of Wuhan as the research object,quantifies and clusters the characteristics of cooling service spillover effects of different types of green spaces,and analyzes and compares green spaces of different cooling service types.Select influencing factors from two aspects of green landscape characteristics and urban form characteristics for correlation analysis,and screen out significantly related factors for relative contribution and marginal effect analysis to clarify their specific impact methods.Finally,establish demand and supply indicators for green space cooling services,match supply and demand in the central urban area of Wuhan,identify areas with imbalanced supply and demand,and optimize them,providing reference for urban green space planning.The main research conclusions of this article are as follows:(1)In the central urban area of Wuhan Center,there are 678 greenbelts showing obvious cooling effect.Among them,the average cooling range of regional green space is the largest,and the average cooling distance of park green space is the largest.The fitting curve of the function between the surface temperature around the green space and the distance to the green space shows that for every 30 m increase in distance to the green space,the temperature can decrease by up to 0.35 ℃.The cooling service of large green spaces can cover more areas and provide stronger cold islands,but the cooling efficiency is not as good as that of small green spaces.When there is water inside the green space,its cooling effect will be significantly enhanced and it is easier for people to feel cool.According to the characteristics of cooling service spillover effects,green spaces can be reclassified into four types: low efficiency,high efficiency,strong cooling,and flexible.(2)The impact of green landscape characteristic indicators on the cooling effect of green spaces is usually greater than that of urban form indicators.The contribution rate of green space area,perimeter,and NDVI within the green space is particularly high.With an area of 60 hm~2、 When the proportion of internal water bodies is 45%,the cooling effect of green spaces reaches its best and does not change.The factors related to water bodies and green spaces show a significant positive correlation with most indicators,while the factors related to buildings show a significant negative correlation.For park green spaces,there are few or no significant cooling effect indicators that are significantly related to building related factors,but more than protective green spaces and regional green spaces.For protective green spaces and regional green spaces,the proportion of water bodies in the buffer zone and the NDVI within the green space are relatively the most influential factors.The three-dimensional architectural factors exhibit the characteristic of facilitating the cooling effect of green spaces when the building layout presents a concentrated low rise or dispersed high rise form.For park green spaces,the area is 80 hectares~2、 The proportion of water inside the green space is 20%,slow when the proportion of water in the flushing area is 30%,the overall cooling effect is the best and does not change.For protective green spaces,the area is within 10 hectares~2、 When the shape index is 5,the overall cooling effect is the best and does not change.For regional green spaces,the area is within 20 hectares~2、 When the shape index is 3.5,there is water inside,and the height of surrounding buildings is 10-15 m,the overall cooling effect is the best and does not change.(3)Most areas in the central urban area of Wuhan Center are in a state of imbalance between supply and demand,dominated by low supply high demand areas and high supply low demand areas.High demand areas for cooling services are mainly distributed in highdensity residential areas,industrial parks,and near stations within the Second Ring Road,while low demand areas are distributed in large green spaces and water bodies,as well as near rural areas on the outskirts of urban areas.High supply areas are distributed near various large parks or scenic clusters,while low supply areas are consistent with the distribution of high demand areas.(4)Put forward the optimization strategy of green space layout from three perspectives of green space landscape characteristics,urban landscape characteristics,and optimization of supply and demand relationship.According to different cooling service needs and green space layout goals,set different green space construction thresholds,provide specific reference suggestions for the planning and layout of green space in the central urban area of Wuhan Center,and provide theoretical support for the construction of green space in Wuhan. |
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