Investigating the heterogeneity of water cooling effect for cooler cities

Abstract Urban heat island (UHI) exerts significant effects on energy consumption and human health. Implementation of green and blue infrastructures can help alleviate urban overheat, especially during warm seasons. However, current studies scarcely considered the heterogeneity of water cooling effect, thus the planning strategies may not be consistent for a variety of situations. This study investigated the water cooling heterogeneity by three main aspects: waterbody, littoral zone, and background climate. The results confirmed the existence of the heterogeneity of water cooling effect, among three lake size groups, six littoral landscapes types and three warm seasons. Firstly, larger lakes presented lower WST (water surface temperature) and higher WCD (water cooling distance) than smaller lakes. Secondly, the Compact lowrise showed the highest mean temperature and lowest cooling distance in littoral areas among six landscapes. Threshold value of efficiency (TVoE) of WCD was much higher than that of WCI. Thirdly, summer period presented the greatest average WCI (water cooling intensity) for all lakes size groups, while spring had the highest average WCD for large and medium lakes. Given the revealed heterogeneity of water cooling effect in three aspects, this study proposed some specific strategies in urban planning for cooler cities.