Coupling mechanism of water and greenery on summer thermal environment of waterfront space in China's cold regions

Water and greenery space is an essential part of the urban ecosystem and plays a vital role in alleviating the urban heat island effect. Water and greenery differently affect the urban microclimate. After coupling the two factors, the quantitative human thermal environmental experience analysis needs to be revealed. This study investigated the thermal environment of the waterfront space with the greenery of Tianjin in the cold regions of China. Different types of microscale water were analyzed to evaluate their thermal environment in summer using subjective and objective analysis and model simulation. We concluded the coupling mechanism of waterfront greenery and thermal evaluation standard. The results show that water and greenery's coupling effect peaked at 14:00 and waterfront at 4-8 m. Conversely, the cooling effect was more significant at 3-6 m from the water's edge, where the location was suitable for construction as verified by the optimization model. The prerequisite of coupling mechanism was suitable green coverage rate and vegetation type, based on the comprehensive analysis of four cases. The objective effects of different waterfront distances on the thermal comfort of Heat Index (HI) and the subjective evaluation of Universal Thermal Climate Index (UTCI) for people were quantified. This research provides a theoretical basis and data support for urban waterfront renewal in cold regions.