关键词: 城市水体, 热缓释效应, 景观特征, 效率阈值, 地表温度, 冷岛效应

Abstract: Clarifying the cooling effect of water body is of great significance to alleviating the urban heat island effect. Ground surface temperature retrieval data from 30 typical water bodies in Changsha were obtained based on the improved single window algorithm. RS/GIS technology, sample image analysis and buffer zone analysis were used to explore the impacts of landscape features on the cooling effect of water body and the efficiency threshold of landscape feature. The area of cooling effects was a more suitable index than the cooling scale in evaluating cooling effect of water body. The area of cooling effects and the intensity of cooling effects had significant seasonal variations. The cooling effect of water body was affected by its own landscape features and surrounding landscape configuration. Water body size and the proportion of green land were important landscape features that enhance the cooling effect of water body, while the role water shape index was limited. The landscape features had efficiency thresholds, which varied with different evaluation indices. In summer, the efficiency thresholds calculated by area and intensity of cooling effects were 30 and 15 hm², respectively. The efficiency thresholds of cooling effects calculated based on perimeter-area ratio, proportion of green land, and the ratio of build-up area to water body area were 1.4, 0.55%, and 11%, respectively. The water landscape features showed scale effect, in that increasing the water shape index would improve the thermal environment of the lakeside area and increasing perimeter-area ratio would make the cooling effect of water body serve a wider range of the city. Our results provide reference for enhancing the cooling effect of water body and guiding the planning and design of urban blue space.

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