The cooling effect of water landscape in high-density urban built-up area a case study of the center urban district of guangzhou

摘要

During rapid urbanization process, one of the most representative environmental problem in the world is the urban heat island (UHI) effect. In contrast to those warming effect, urban water bodies which are known as `urban cool islands' (UCI), have been considered as an effective measure in alleviating UHI effects and improving urban thermal environment. Therefore, it is of great significance to study how the water landscapes influence the urban thermal environment. However, previous studies paid less attention on the effect of water bodies' configuration and its surrounding landscape components on water bodies cooling effect. In this study, the SPOT-5 and Landsat-8TIRS images are applied to extract the urban water landscape and land surface temperature (LST) in the center urban districts of Guangzhou, investigating the impact of water bodies' characteristics on cooling intensity and influencing scale. The cooling effect intensity and influence scale are quantified as the LST difference and distance between water bodies and continuous buffers. The result reveals that: (1) the water bodies' characteristics (water area and shape index) had a strong effects on its temperature. In detail, with the increasing of the water area, the water average temperature is significantly decreased, but when the water area increase to 20ha the average temperature will not decrease with the increase of the area, which is reflected the saturation trend of cooling effect; (2) the cooling effect intensity and influence scale are also found to determine by both water bodies' characteristics and surrounding built-up area. The high proportion of built-up areas to some extent may increase the cooling effect intensity. Results of this study expands our scientific understanding of how the water bodies characteristics and its surrounding environment affect the cooling effect and influence scale and help urban planners to design urban water bodies to have a better cooling effect.