Effects of pavement watering on the thermal environment above an impermeable pavement in a hot and humid area

Pavement watering is an effective evaporative cooling strategy for alleviating the heat of pavements, but its effectiveness on impermeable pavements in hot and humid areas needs to be verified. This study both qualitatively and quantitatively investigated the effect of pavement watering on the thermal environment above an impermeable pavement in Guangzhou. The results showed that pavement watering reduced the upward shortwave and longwave radiation, resulting in an increase in net radiation that could be offset by the latent heat (Q(E)) of water evaporation, thereby reducing the surface temperature (T-s), sensible heat and heat storage of the pavement. The reduction in T-s was a significant factor contributing to the improvement of thermal environment parameters. High humidity levels are not favorable for the reduction in T-s and evaporative cooling in hot and humid regions. However, the exponential function between Q(E) and relative humidity (RH) indicated when RH approached 100 %, the Q(E) value could converge to approximately 178 W/m(2). Bowen ratio revealed that the pavement was able to imitate a highly evaporative environment by pavement watering. Furthermore, the biometeorological indices in hot and humid area were moderated by the synergistic effect of reduced T-s and increased wind speed, which was benefit from evaporative cooling.