Influence of Water Bodies on Outdoor Air Temperature in Hot and Humid Climate

Water features, within an urban area have a positive effect on the microclimate of the surrounding areas when natural cooling from evaporative process is needed in the hot sunny day. The increased availability of water usually enhances evaporation, and the associated uptake of latent heat provides and additional daytime cooling effect. The water bodies of the river operate as the cooling source on the microclimate of the surrounding area. Air temperature near or over bodies of water is much different from that over land due to differences in the way water heat and cool. Water bodies are noted to be about the best absorbers of radiation, but on the other hand, they exhibit very little thermal response. Many other researches argued that evaporative cooling from water bodies or water features is yet one of the most efficient ways of passive cooling for building and urban spaces. However, evaporative cooling may not work optimally in a hot humid tropical country due to its relatively high humidity. This paper studies the evaporative cooling performance of a waterway of approximately 70m to its surrounding micro-climate. The waterway is situated in Kallang, Singapore. The air temperature and relative humidity are measured continuously for five months, May and September 2010, to find the clear extent of the cooling effect from the waterway horizontally. There is a total of 10 measurement points in each location, where five points of measurement are located along the waterway and another five points of measurement are located moving away from the waterway in order to observe the extent of its cooling effect.