Blue-Green infrastructure determines the microclimate mitigation potential targeted for urban cooling

Abstract

Urban Heat Island (UHI) exacerbated by global warming can increase the thermal load in cities, which leads to more extreme climate events. One of the strategies to mitigate the impact of extreme climates and UHI is through nature-based solutions such as the Blue-Green Infrastructure as it provides environmental and community benefits However, Blue-Green Infrastructure’s role in urban cooling in the tropics still needs to be further investigated. Therefore, this study examined the role of Blue-Green Infrastructure on microclimate modifications in an urban park. Microclimate measurements were made using systematic random sampling with random start (total of 64 sampling points) at a waterbody (Blue Infrastructure) and tree and grass (Green Infrastructure) areas during solar noon time (1200-1400). Blue-Green Infrastructure showed greater microclimate benefits compared to the open space with the reduction of air temperature by up 1.6°C. However, green infrastructure had greater cooling benefits compared to Blue Infrastructure especially trees with significantly lower air temperature and solar radiation interception (0.71°C and 250.3 W/m2, respectively) as well as higher relative humidity (12.17%). Moreover, stand characteristics determine the microclimate mitigation function. This study provides a useful indication of the role of blue and green spaces in urban cooling, where it further emphasizes the importance of Blue-Green Infrastructure utilization in urban landscapes. It further recommends that urban planners, managers and policymakers should consider these strategies for urban cooling purposes : 1) Utilising Blue and Green Infrastructures especially trees 2) Tree canopy cover and DBH should be set as priority traits.