Cooling Effects of Blue and Green Infrastructure on Urban Microclimate: A Case Study at Thu Duc District, Ho Chi Minh City

Blue and green infrastructure are potential nature-based solutions to the critical climatic impacts in dense city areas like Ho Chi Minh City. However, their impacts have been more theoretically investigated. This study aimed to practically examine the potential effects of the blue and green infrastructure on urban microclimate using a case study with scenario analysis. An existing residential area in Thu Duc District was taken for thermodynamic simulations with various open-source data. Findings were generated by the calculation and demonstration of the air temperature, relative humidity, and heat index values presented at different locations and elevation levels. The findings confirmed the cooling effects of blue and green infrastructure in mitigating severe microclimatic conditions and therefore reducing health-related risks. Taking effects up to the pedestrian level, blue infrastructure was significantly efficient in heat stress reduction with almost 40% less danger and a provide of approximately 10% of the safe time period, compared to the baseline scenario. The effects were presented at and close to the water body as well as following the prevailing wind direction. Green infrastructure cooled down the areas along the greenery surfaces due to the reduction of radiant heat flux of 24-36 W/m², especially from the built surfaces towards the sun direction. The numerical and spatial outputs of the cooling effects imply the significance of blue and green infrastructure in mitigating the severe urban microclimatic conditions. Besides, these measures can also improve land use efficiency and provide further benefits regarding psychological impacts and urban biodiversity.