Restoration of an inner-city stream and its impacts on air temperature, relative humidity, and perceived temperature

Spatiotemporal changes in thermal environment due to the restoration of an inner-city stream called ‘Cheonggye' in Seoul were analyzed using the perceived temperature (PT) model. PT was used as a standard index of thermal balance of human beings in thermo-physiological environment. The stream, running through the center of Seoul for 5.8km from west to east, had been covered by concrete structures and asphalt pavement roads for 46 years and was restored as a small (ca. 6m width and 40cm depth) inner-city stream in 2005. Air temperature and relative humidity were monitored before, during, and after the restoration around the stream by installing 13 data loggers at various distances from 28 to 826m from the center of the stream. The temperature anomaly between the monitoring sites and surrounding metropolitan area was dropped by 0.13C on average at the center of the stream after the restoration along with humidity increase across the stream area. Seasonal variations of PT by the restoration were compared to elucidate the changes of local thermal environment near the stream. Spatial variations of PT around the stream and the metropolitan area were also analyzed to demonstrate the restoration effects on local climate. Vegetation around the stream was also restored and the consequent changes regarding PT were investigated. The observed temperature drop due to the restoration can be considered as a counter measure against urban heat island. This study provides scientific reference data on local-scale thermal comfort due to a restoration of a small stream with vegetation in urban area.

This study was supported by the basic research grant of METRI/KMA.