How can urban water bodies be designed for climate adaptation?

With rapid urbanization and population growth in Beijing, urban heat island (UHI) effects have become ever stronger. Methods for reducing the UHI effects by landscape design are becoming increasingly critical in urban planning studies. Water bodies form urban cooling islands (UCI) to mitigate the UHI effects. This study investigated the UCI intensity and efficiency of 197 water bodies in Beijing, and their relationships with four descriptors of microclimatic landscape design, including the water body area (WA), geometry (landscape shape index, LSI), location (DIST) in reference to a defined city center, and surrounding built-up proportion (PB). Data of land cover and land surface temperature (LST) were extracted from ASTER images of August 8 of 2007. The UCI intensity was defined as the maximum LST gradient outside a water body area, while the UCI efficiency was used to represent the UCI intensity per unit area of a water body. The results indicated that: (1) the mean UCI intensity and efficiency was 0.54 °C/hm and 1.76 °C/hm/ha, respectively; (2) the UCI intensity was positively correlated with WA and PB, and negatively correlated with LSI and DIST; and (3) the UCI efficiency was positively correlated with PB, and negatively correlated with WA, LSI and DIST. Results of this study may help urban planners and designers in decision making to achieve optimal urban landscape designs for a more ecologically sound and pleasant living environment.

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► We investigated intensity and efficiency of cooling effects of urban water bodies.
► Large area intensify cooling intensity but reduce cooling efficiency.
► Regular shape intensify cooling effects.
► Cooling effect is stronger near downtown or in densely built-up areas.
► These findings provide useful information for landscape design and planning.