| The urban heat island(UHI)effect is caused by the rapid construction and development of cities,resulting in changes in land cover and increased human activity,which leads to changes in the thermal characteristics of urban underlying surfaces.The UHI effect not only affects the urban atmosphere,weather,and climate but also poses a threat to the health of urban residents.Analyzing the spatiotemporal characteristics of the UHI effect and taking cooling measures have important significance for mitigating the UHI effect.Correspondingly,in this study,a mono-window algorithm was used to retrieve land surface temperature(LST),and WUDAPT was used to categorize local climate zones(LCZ).Based on this,the study calculated the UHI intensity and analyzed the spatiotemporal variation characteristics of the UHI effect.Coupled with the interval linear programming method,a model for optimizing the configuration of cooling measures to mitigate the UHI effect was constructed.The model aims to minimize the total LST difference between the cooling measure configuration area and the dense trees area.This study provides optimization schemes for cooling measures in various decision scenarios and proposes feasible suggestions for optimizing the configuration of cooling measures.The case study was carried out in Shenzhen,Guangdong Province.The main results are introduced as follows:(1)This study utilized remote sensing data of Shenzhen in 2009,2014,and 2019 to retrieve land surface temperature,categorize LCZ,and calculate the UHI intensity,in order to analyze the spatiotemporal characteristics of the UHI effect.Results indicate that,in terms of spatiotemporal variation of land surface temperature spatiotemporal variation,Shenzhen had the highest temperature and the UHI ratio index in 2014.The main reason for the difference in surface temperature within each administrative district was the variation in the proportion of impervious surfaces and natural covers.Regarding the spatiotemporal variation of LCZ classification for Shenzhen from 2009 to 2019,under the built types,the area of open high-rise buildings increased the most,while the area of large low-rise buildings decreased the most.Under the land use types,the area of paved increased the most,while the area of low plants decreased the most.Impervious surface areas extended beyond the coastline and gradually expanded towards green spaces in inland areas.Based on the transfer matrix of LCZ,large low-rise buildings transformed into mid-rise and high-rise buildings,and green space mainly transformed into buildings and paved.From the spatiotemporal variation of the UHI intensity based on LCZ classification,among the built types,the highest temperature was found in the large low-rise buildings and the heavy industrial zones.In the land use types,the highest temperature was found in the paved zone.The UHI intensity was generally higher in the built types than that in the land use types.In the year with higher land surface temperature,the differences in the UHI intensity among various LCZ were more significant.(2)An optimization model for cooling measures to alleviate the UHI was developed through integrating surface temperature,categorize LCZ and interval linear programming.The model can handle interval uncertainty information such as the cooling effect,cost,and area of cooling measures during the allocation process,and obtain optimized cooling measure configuration schemes under different decision scenarios.The results indicate that under the existing policy environment,at least 20% of Shenzhen’s energy-saving and environmental protection expenditures are required to be allocated for cooling measures.On the basis of the cooling expenditure not being lower than 20% of the energy-saving and environmental protection expenditures,the optimization of cooling measures can enhance the effect of mitigating the UHI effect as the cooling expenditure increases.The configuration of cooling measures can significantly reduce the surface temperature in administrative districts with large building areas and hard pavement areas.However,in administrative districts with relatively high green coverage,the cooling effect produced by configuring cooling measures is not significant due to the limited area available for implementing such measures.Regarding the measures themselves,green roofs require higher funding than other measures,while their minimum implementation area is constrained by green coverage and roof greening rate.The implementation area of the measure for transforming scattered trees into dense trees gradually increases with the growth of in funding and is primarily constrained by the protection of non-convertible land.The implementation area of the measures for transforming shrubs into dense trees and low plants into dense trees is mainly affected by the dual constraints of green coverage and nonconvertible land.The configuration of cooling measures can effectively mitigate the UHI effect,and administrative districts with a high proportion of building and hard pavement areas require more measures.Suggestions were made to adjust the ratio of cooling measures configuration expenditure to energy-saving and environmental protection expenditure,increase the proportion of cooling measures configuration expenditure in administrative districts with larger building and hard pavement area zones,configure more cooling measures,decrease the proportion of cooling measures configuration expenditure in administrative districts with larger green area zones,and configure fewer cooling measures.This study analyzed the spatiotemporal characteristics of the UHI effect by inverting land surface temperature,local climate zones,and calculating UHI intensity.In conjunction with interval linear programming,uncertainty information on the optimal configuration of cooling measures to mitigate UHI at the urban level was addressed,and an optimization model for cooling measures to mitigate UHI was proposed.This model can provide decisionmaking options for cooling measures in different decision scenarios and propose feasible suggestions to mitigate UHI.Based on research results in Shenzhen,feasible suggestions have been provided not only for the alleviation of the UHI effect and urban ecological planning of Shenzhen,but also serve as inspiration for other cities’ mitigation of the UHI effect. |
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