Seasonal variations and main influencing factors of the water cooling islands effect in Shenzhen

Enhancing the water cooling islands (WCIs) effect of urban water bodies is one strategy to alleviate high tem-peratures in urban areas. At present, the influencing factors of WCIs effect have been investigated compre-hensively, but the relative importance of these factors has not been compared. In this case, urban planners cannot give priority to the most important factors when using WCIs to weaken urban heat islands effect in urban planning. Shenzhen, located in the south of Guangdong Province, China, is a rapidly urbanizing city with abundant urban water bodies. The urban heat islands effect in Shenzhen has already become severe as the city is affected by the climate and the urbanization process. This study compared the seasonal variations of WCIs in Shenzhen and explained WCI intensity based on landscape pattern, geographical location, and surrounding land cover. The main influencing factors of the WCI intensity were identified by stepwise regression analysis. The results showed that the WCIs effect was evident in all four seasons, and the intensity of cooling was the greatest in the summer, followed in decreasing order by autumn, spring, and winter. The main influencing factors found in this study include water area, elevation, and surrounding land cover. In general, surrounding land cover has a greater impact than water area during all four seasons and has a greater impact than elevation in spring, summer, and autumn. These main influencing factors have a greater impact than other factors and can be used as indicators to predict the WCI intensity of water bodies in the future. In addition, the threshold of water area affecting WCI intensity was observed, and the heat island water bodies were found in all four seasons. Among the surrounding land cover buffers of water bodies, the optimal buffer was the most correlated to the WCI intensity, and the warmer the season, the smaller the optimal buffer. This study highlights these main influencing factors, and they will help urban managers reasonably modify existing water bodies or plan new ones.