Field observation was carried out around the Turumi river and in the Tama river to estimate their cooling effect on the thermal environment in the surrounding area. The hourly measurement of air temperature distribution revealed that the affected zone by the Turumi river was restricted to the region close to the river course. The infrared thermal image sensor was applied to identify the correlation between the land cover and the surface temperature in the Tama river. It was found that at noon the surface temperature was the highest on revetment works, then pavements, playground and the lowest on grass field.