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RP2014: Conference paper: Thermal impact of blue infrastructure: Casestudy Cheonggyecheon, Seoul (Korea)

Higher densities tend to experience a relatively hotter surface temperature, compared to their peri-urban surroundings. This artificial heat stress in cities is denoted the Urban Heat Island (UHI) effect. Urban geometry, landscape, land surfaces and anthropogenic waste heat are cited as the UHIs’ key contributors. However, magnitude and distribution of the UHI effect varies in different cities due to different regional climates, urban land use patterns and scales of investigation. Seoul, the capital of the Republic of Korea, is influenced like many other large cities by the urban heat phenomena.

The urban heat phenomena are typical for a metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. Special geographical and political conditions are combined with a high population density, remarkable high-rise buildings and small open spaces are characteristic for Seoul. The city of Seoul (9.8 Million inhabitants) is located in a valley surrounded by mountains in the north and south. Furthermore, in 1972 a restricted development zone (RDZ) precinct was established by the government. This is essentially a Greenbelt that has a size of 1,567 km². This greenbelt is more than two times larger than the city of Seoul. Seoul has an area of 605 km². All urban development within the RDZ has been prohibited during the last four decades.

The calculated land surface temperature (LST) in this paper was obtained by using the satellite Landsat-7. It was carried out a calibration of the data on the probe specificity, the emission and the transmittance. The resolution of the images is 30 meters. Satellite maps are available for free at the NASA based remote sensing platform (Earthexplorer 2015).

We investigated the micro-climate changes and urban-scale cooling load reduction which has resulted from the so called Cheonggyecheon water stream. This stream is located in central Seoul and runs from the northern central business district into the Han-River.

After the Korean war (1950-1953) the Cheonggyecheon river was for more than 50 years covered with pavement and concrete overpass structures. The reconstruction of the expressway was carried out from 2002 to 2005. To estimate the thermal impact of the expressway into a water pathway remote sensing analysis (Landsat 7 ETM+) was undertaken. 20 Landsat-7 ETM+ images from 2000 till 2012 were used to compare the land surface temperature (LST) distribution during the time the expressway was there and through to the reconstruction and the establishment of the river stream. A built-up area of two km width surrounds the new water pathway and this was used as a reference area.

The investigation could show that the establishment of the Cheonggyecheon stream forced a considerable thermal impact, i. e. an average decrease in the land surface temperature by seven degrees Celsius.

Read the paper HERE.

RP2014: Quantifying the Contribution of Green Infrastructure to Carbon and Energy Performance