The win-win interaction between integrated blue and green space on urban cooling

Abstract

The contributions of urban blue and green spaces on urban cooling are widely acknowledged. However, the combined cooling effect of integrated blue and green space remains uncertain. In this study, a combination of modelling and observational analyses uncovered a win–win interaction between coexisting blue and green spaces in terms of urban cooling. That is, the integration of water bodies and green spaces can reinforce the mutual cooling potential and provide greater urban cooling than stand-alone water bodies and green spaces. The results indicated that the known influencing factors such as area, shape and planting structure had no impact on the cooling effect of riverside urban green spaces. Instead, the width of the adjacent river reach and the degree of contact with the reach were significantly positively related to the cooling effect of riverside green spaces. The surface/air temperature of a riverside green space can be 4.2 °C/3.7 °C lower in the daytime in summer, and 3.1 °C/2.7 °C lower in spring than a non-riverside green space of similar size. Urban green spaces with water bodies inside could cause about 0.99 °C and 1.45 °C more deduction of land surface temperature (LST) than simple green spaces of similar size in spring and summer, respectively. There were about 1 °C‑2.9 °C more deductions in the air temperature of a river reach when it is accompanied by green spaces. More specifically, complete coverage with vegetated areas within a 30 m buffer on both riverbanks can result in a 3.1 °C and 3.37 °C higher LST deduction compared to no vegetation coverage on the riverbank in the daytime in spring and summer, respectively. The results of this study extend the understanding of the cooling effect of urban blue-green spaces and provide implications for sustainable urban planning.