The Cheonggyecheon restoration is an outstanding example of sustainable urban development. It revived a cultural and natural asset of Seoul, the Cheonggyecheon stream, which had been a landmark central to the city's history and to its people.
Around 1958, people began settling near the stream without drainage or sanitation. As informal housing and pollution grew, the stream was buried under a concrete road, and a six-lane elevated expressway was later built over it to carry traffic between north and south Seoul. By 2003 the expressway carried around 180,000 vehicles a day. The area had 200,000 shopkeepers and 60,000 businesses and served almost a million people moving through it. Eventually it reached saturation and began to decline quickly.
Challenges
By around 2000 the expressway was outdated and structurally unsound; its foundations were being corroded by concentrated gases. Heavy traffic pushed air and noise pollution beyond standards, leaving residents vulnerable to respiratory disease. Companies moved to Gangnam, businesses closed, and population and employment fell steeply. Even so, demolishing the highway seemed impractical to many locals. Shops and businesses strongly opposed it, fearing it would cut off customers, and transport experts warned it would choke traffic (ITDP, n.d.).
Solutions
The Seoul Metropolitan Government decided to take the highway down. To keep the city connected, it built 10 pedestrian bridges and 10 vehicle bridges, improved public transport and discouraged private vehicles. Winning over shop owners was one of the hardest parts: the government held more than 4,000 meetings with them, provided economic support to many, and consulted widely with other stakeholders. 96% of the concrete and asphalt from the demolition was reused in the landscaping. The revival of the stream's cultural and natural value has also made the area more resilient to climate change.
Ecosystem services and climate resilience
The stream's ecosystem was restored through a deliberate mix of grey and green infrastructure. The table below links the ecosystem services restored to their contribution to climate resilience.
| Ecosystem service | What the restoration did | Contribution to climate resilience |
|---|---|---|
| Urban temperature regulation | Introduced water and vegetation as natural capital | Ambient temperature fell from 36.3°C to 32.7°C. Vegetation and water cool through evapotranspiration, breeze cycles and shade; water bodies absorb heat in summer and release it in winter. |
| Noise reduction | Removed the expressway; added vegetation and water | Noise levels fell with less traffic. Vegetation, soil and leaves absorb sound energy. |
| Air purification | Introduced vegetation | Air quality improved significantly: a 34% reduction in NO₂ and a 19% decrease in PM10. |
| Moderating climate extremes | Restored riparian and other ecosystems; reopened the stream corridor | The corridor acts as resilient infrastructure against heat and heavy rain; marshy areas slow water flow and reduce flooding. |
| Runoff mitigation | Converted impervious land to pervious; restored the water corridor and soft landscapes | The stream section can handle a 200-year flood and a flow rate of 118 mm/hr. Vegetation intercepts stormwater and helps groundwater recharge. |
| Waste treatment | Introduced varied ecosystems | Bioremediation by planted species helps filter water and treat waste naturally. |
| Global climate regulation | Restored and protected natural ecosystems | A small contribution at city scale, but meaningful at landscape level, since the stream is part of Seoul's drainage basin. |
| Recreation | Landscape design along the restored stream | Created public space where people can engage with a natural landscape along the entire stretch. |
| Aesthetics, cognition and social cohesion | Landscape design along the restored stream | Festivals, activities and interaction bring people together; green space improves psychological health and reduces stress. |
| Habitat provision | Restored ecosystems | Biodiversity revived, with a rise in the number of species. |
Advantages and disadvantages
Advantages
- Recovered cultural and natural beauty and changed Seoul's overall cityscape.
- Opened opportunities for businesses to grow, improving the local economy.
- Promoted sustainable transport through better public transport.
- Contributed to climate resilience.
- Conserved ecosystems and enhanced ecosystem services.
Disadvantages
- The approach could have been more holistic across the whole drainage basin; it did not revive the sub-tributaries.
- Some organisations argue the restoration was not authentic to the historical and natural context.
New approaches for reviving cultural and natural assets
Urban ecological filters
Urban growth has damaged ecological networks worldwide. More impervious surface and less vegetation reduce infiltration and increase stormwater runoff, which erodes topsoil and stream banks, carries pollutants into streams and starves groundwater. Urban Ecological Filters, an integrated system of ecological components, would restore stream networks and improve water quality across a catchment by building ecosystem services into existing land use. Their design adapts to context, and because they are living systems, they evolve over time into resilient infrastructure for a changing climate. They can be applied to streets, natural ecosystems and open spaces.
Bio-urbanism
Bio-urbanism can be implemented through a flow model, the Urban Ecological Corridor, bringing community, ecology and architecture together around four Rs: reduce, reuse, recycle and regulate. Corridors replace artificial systems with natural ones and speed the recovery of ecosystem health. Integrated with the built environment through socio-ecological models, they can shape green infrastructure alongside energy, waste and transport, and regulate the biophysical processes behind ecosystem services: recreation, water and nutrient regulation, soil formation, waste treatment, biological control, habitat and biodiversity, micro-climate regulation and carbon sequestration. Corridors also connect habitat patches for the exchange of materials and energy, and help tackle heat islands, air and water pollution and waste.
Conclusion
Both theory and case studies suggest that reviving cultural and natural assets can help mitigate the effects of climate change. Old and new approaches can be combined to rejuvenate urban spaces while preserving heritage, conserving natural resources and building climate resilience.
Bibliography
- "Case Study: Cheonggyecheon; Seoul, Korea." Global Designing Cities Initiative.
- "Cheonggyecheon Stream Restoration Project." Landscape Performance Series.
- "Connecting Biodiversity and Climate Change Mitigation and Adaptation." Secretariat of the Convention on Biological Diversity, 2009.
- Daly, K., Dowens, J. & Megarry, W. "Cultural Heritage Has a Lot to Teach Us about Climate Change." The Conversation, 16 October 2018.
- Elmqvist, T. et al. (eds.), 2013. Urbanization, Biodiversity and Ecosystem Services: Challenges and Opportunities. Springer.
- Gómez-Baggethun, E. et al., 2013. "Urban Ecosystem Services," in Elmqvist et al. (eds.), pp. 175–251.
- ITDP. "Revitalizing a City by Reviving a Stream." development.asia.
- Kim, D. & Albert, I., 2016. "Regenerating Green Spaces in the Urban Fabric."
- "Korea Now and Then: Cheonggyecheon." Koreabridge, 17 June 2011.
- Lee, I., 2006. "Cheong Gye Cheon Restoration Project." Seoul Solution.
- Milne, G., 2013. "Embodied Energy." Australian Government, YourHome.
- "Resilient Societies." UNESCO.
- Sawhney, P. & Perkins, M.A., 2015. "Emerging Climate Change Adaptation Issues in the Asia-Pacific Region." Asia Pacific Adaptation Network.
- "Seoul Urban Regeneration: Cheonggyecheon Restoration and Downtown Revitalization." Seoul Solution, 21 April 2017.
- TEEB, 2011. TEEB Manual for Cities: Ecosystem Services in Urban Management.
- The Preservation Institute, 2007. "Seoul, South Korea: Cheonggye Freeway."