1. General information
Location and description of the intervention
City or FUA
Seoul
Region
Asia
Native title of the NBS intervention
청계천
Short description of the intervention
The Cheonggyecheon Stream Restoration Project saw the dismantling and removal of an elevated freeway and the uncovering of a 5.84km section of the Cheonggyecheon historic stream in the centre of Seoul, South Korea (Ref. 2). One of the world’s largest and most densely populated cities, the revitalisation of the Cheonggyecheon Stream has provided Seoul with an ecologically sensitive green pedestrian corridor in an area that was previously recognised as being congested, overpopulated and polluted (Ref. 4). The restoration has provided environmental, social and economic benefits within its immediate proximity (Ref. 2). In addition to becoming a "vehicle for revitalisation, urban renewal and economic development", it has "also signified a shift in Korean planning priorities", with both city authorities and residents now placing an emphasis "on health, sustainability and social responsibility" (Ref. 4). It has further "become a template for planning intention and action across South Korea" (Ref. 4).
Address

1 Cheonggyecheon-ro
Seorin-dong, Jongno-gu
Seoul
South Korea

Location
The NBS is situated in an area, with clear delineation of boundaries and a specific shape (polygon). The NBS project can also have more than one area location (more than one polygon, situated close by).
Area boundary
POINT (126.977503 37.569231)
POINT (126.982502 37.56886)
POINT (126.987265 37.568146)
POINT (126.992154 37.568361)
POINT (126.99774 37.568841)
POINT (127.001881 37.569615)
POINT (127.015679 37.569825)
POINT (127.02319 37.571783)
POINT (127.035677 37.572146)
NBS area image
Source of NBS area image
Aerial Map of the eight stream sections extracted from Ref. 5 (https://www.kdevelopedia.org/Development-Topics/themes/--13); Secondary aerial map sourced from Google Maps.
Total area
4047000.00m²
NBS area
252000.00m²
Type of area before implementation of the NBS
Central Business District / City Centre
Other
Please specify “other type of area” before implementation of the NBS
The NBS is located in place of an overhead freeway which had been built atop the stream. Work to cover the stream began in 1918, it was finally fully covered between 1958 and 1961 and a four-lane overpass was built in 1971 (Ref. 4).
Website of the intervention
https://www.sisul.or.kr/open_content/cheonggye/intro/summary.jsp
Timeline of intervention
Start date of the intervention (planning process)
2001
Start date of intervention (implementation process)
2003
End date of the intervention
2005
Present stage of the intervention
Completed
Goals of the intervention
The restoration project had five main purposes: to signal a transfer to sustainable urban development paradigm; to promote the recovery of eco-friendliness; to remove risks related to the concrete covering and elevated highway; to aid the restoration of historical and cultural spaces, and to provide balanced development between different areas within the city (Ref. 1). To achieve these purposes, three objectives were specifically targeted: restoration of a natural environment and enhancement of the quality of life; restoration of history and culture; and revitalisation of the economy (Ref. 1).
As summarised by Ref. 5, "The essence of the restoration program was “space creation” – a place where the city’s residents could enjoy the ‘liveliness of a friendly Seoul.’ Defined concepts of history (tradition), culture (modernity), and nature (future) were introduced to confer diversity onto the respective sections of restored areas". Flood management was a further key component of the restoration, with particular emphasis on its being able to respond to "increasing incidences of flooding and the frequent torrential showers during summer [hence] the city built embankments that can withstand a 200-year-level extreme flood" (Ref. 5). Additionally, the number of bridges along the route of the restored stream were to be minimised "in order to transmit a maximum amount of water" (Refs. 5 & 6).
Quantitative targets
5.48km of the Cheonggyecheon stream were to be uncovered and restored and a landscaped green pathway to run along its banks (Ref. 4). The resulting green corridor was to run from "Seoul to an ecological conservation area outside the city and is split into three zones which mark the transition from an urban landscape to a natural environment" (Ref. 4).
Monitoring indicators defined
Monitoring indicators are now available for the landscaping greenery (number of species and individual plants), fish (number of classes and species), representative flora and fauna, water quality (aiming for Biochemical Oxygen Demand 2 or less, Total Phosphorus 0.04 or less according to the notification of the Ministry of Environment) and monitoring is also conducted of potential flood risk, including disaster prevention weather information; real-time monitoring of weather conditions; and riverbed monitoring through CCTV (Ref. 6). It is unclear whether these monitoring indicators were devised prior to the NBS implementation, whether they arose during the planning process, or whether they have arisen post-NBS implementation.
Sustainability challenge(s) addressed
Climate action for adaptation, resilience and mitigation (SDG 13)
Climate change adaptation
Environmental quality
Air quality improvement
Green space, habitats and biodiversity (SDG 15)
Habitat and biodiversity restoration
Green space creation and/or management
Regeneration, land-use and urban development
Promote natural styles of landscape design for urban development
Water management (SDG 6)
Flood protection
Stormwater and rainfall management and storage
Improvements to water quality
Cultural heritage and cultural diversity
Protection of historic and cultural landscape/infrastructure
Economic development and employment (SDG 8)
Tourism support
Climate change adaptation: What were the goals of the NBS?
Reduce exposure to climate risks directly
Reduce the impacts of climate risks events on urban places and communities
Climate change adaptation: What activities are implemented to realize the conservation goals and targets?
Increase or improve urban vegetation cover to help reduce outdoor temperature
Create or improve outdoor spaces to help people escape from urban heat
Renaturalization of rivers and other water bodies
What types of restoration goals are / were defined for the NBS intervention?
Ecosystem-focused
What activities are implemented to realize the restoration goals and targets?
Rehabilitate and restore damaged or destroyed ecosystems
Implementation activities
By removing the overhead freeway and opening up the stream, the stream has been re-naturalised. Benefits were hoped to be had on the ecosystem through improving both water and air quality and increasing biodiversity; on society, particularly through providing flood protection and reducing the impacts of the urban heat island effect; and on the economy, particularly through boosting tourism and foreign investment, and by improving the profitability of existing businesses adjacent to the stream (Ref. 2).
Type of NBS project
Creation of new green areas
Management and improved protection of rivers and other blue areas
Ecological restoration of ecosystems
NBS domain and interventions
Ecological domain(s) where the NBS intervention(s) is/are implemented
Blue infrastructure
Rivers/streams/canals/estuaries
In-land wetlands, peatlands, swamps, and moors
Grey infrastructure featuring greens
Riverbank/Lakeside greens
Parks and urban forests
Green corridors and green belts
Vegetation Type
Grass
Shrubs
Trees
Please specify how many trees were planted
Unknown
Please specify other amenities offered by the NBS
Recreational areas were also included into the restoration of the river (Ref. 4), but it is unclear exactly what these comprise.
Amenities offered by the NBS
Benches and drinking water stations
Swimming areas
Cultural (museum, concert areas)
Educational and research amenities (nature protection centre, monitoring stations)
Viewing and outlook points
Other
Services
Expected ecosystem services delivered
Regulating services
Local climate regulation (temperature reduction)
Air quality regulation
Flood regulation
Water purification / filtration
Habitat and supporting services
Habitats for species
Cultural services
Tourism
Aesthetic appreciation
Inspiration for culture, art and design
Mental and physical health and wellbeing
Physical and experiential interactions with plants and animals
Scale
Spatial scale
Micro-scale: District/neighbourhood level
Beneficiaries
Primary Beneficiaries
Local government/Municipality
Private sector/Corporate/Company
Citizens or community groups
Young people and children
Other
Please specify "other primary beneficiary"
Primary beneficiaries were also considered to comprise local pre-existing businesses, and additionally the wider city through attraction of foreign businesses (Ref. 1).
Governance
Governance arrangements
Government-led
Please specify the roles of the specific government and non-government actor groups involved in the initiative
The government led the restoration of the stream, headed by the Mayoral candidate of the time, Myungbak Lee, who "established as his major campaign pledge the restoration of Cheonggyecheon" (Ref. 8).
Key actors - initiating organization
Local government/municipality
Land owners
Public space owned by the city
Key actors - Other stakeholders involved (besides initiating actors)
Local government/municipality
Non-government organisation/civil society
Citizens or community group
Researchers/university
Please specify other participatory methods
"Upon inauguration, the Cheonggyecheon Restoration Headquarters, the Cheonggyecheon Research Group, and the Cheonggyecheon Citizens’ Committee were established to handle research activities related to the restoration" (Ref. 8), however, Ref. 4 highlights that "There was not any public consultation on the design of the Cheonggyecheon project, so the views and needs of these groups were not raised [and] although an inspirational space which is family-friendly and welcoming to a wide range of groups, the scope of the project to be truly public and genuinely designed for everybody was undermined by a lack of inclusive planning".
Land owners
Public space owned by the city
Participatory methods/forms of community involvement used
Taskforce groups
Co-management/Joint management
Other
Policy drivers
NBS intervention implemented in response to an Regional Directive/Strategy
No
NBS intervention implemented in response to a national regulations/strategy/plan
No
NBS intervention implemented in response to a local regulation/strategy/plan
No
Mandatory or voluntary intervention
Voluntary (spontaneous)
Please specify other type of voluntary intervention
As summarised by Ref. 8, "the Stream restoration idea was not included in the official urban planning documents" for the city, yet "despite historical reluctance over any potential project, discussions about regeneration began as the Mayoral candidate, Myungbak Lee, established as his major campaign pledge the restoration of Cheonggyecheon". This coincided with the city’s announced plan to "demolish and reconstruct the elevated highway...partially as a result of an investigation that revealed corrosion in the highway’s steel frame construction, which made it evident that the 30-year-old road would cost substantial sums of money to fix and maintain", hence plans to restore the stream in favour of reconstructing the four-lane therefore developed along political lines during the mayoral election (Ref. 8).
Enablers
Presence of specific city-level GI/NBS vision/strategy/plan - mentioned in connection to the project
No
Presence of specific city-level GI/NBS section/part in a more general plan - mentioned in connection to the project
Yes
Please specify the general plan with GI/NBS section
Leveraging the development potential which increased as a result of the Cheonggyecheon restoration, the 'Downtown Management Plan' (2000) was revised, and renamed as the 'Downtown Development Plan' (Ref. 9).
If there is a relevant strategy or plan, please specify the theme / type of the plan.
Urban redevelopment plan
Please specify other vegetation type
Unknown
Presence of city network or regional partnerships focused on NBS - mentioned in connection to the project
Unknown
Presence of GI / NBS research project - mentioned in connection to the project
Unknown
Subsidies/investment for GI / NBS in the city - mentioned in connection to the project
Unknown
Co-finance for NBS
No
Co-financing governance arrangements
No
Was this co-governance arrangement already in place, or was it set up specifically for this NBS?
Not applicable
Financing
Total cost
€100,000 - €500,000
What is/was the Cost/Budget (EUR) of the NBS or green infrastructure elements?
86,584.11 EUR
What are the total amount of expected annual maintenance costs?
1409.88 EUR - 2479.19 EUR annual maintenance costs incurred since project completion (Ref. 6).
What is the expected annual maintenance costs of the NBS or GI elements?
1409.88 EUR - 2479.19 EUR
Please specify cost savings
"Had the Cheonggyecheon Expressway remained, it would have required 100 billion won ($90 million USD) and 3 years of repairs to secure the safety of the ag[e]ing structure. While these costs would be approximately 289 billion won ($260 million USD) less than the cost of the Cheonggyecheon Stream Restoration, the restoration has served as a catalyst for an estimated 22 trillion won ($1.98 billion USD) worth of capital investment in Cheonggyecheon-area redevelopment that would not have otherwise been invested" (Ref. 2).
Please specify total cost (EUR)
386,739,000 South Korean won = 279048.70 EUR (1 won = 0.00072 EUR)
Acknowledging that some discrepancies exist in the total project expenditure reported by Refs. 2 and 8, Ref. 8 provides a breakdown of the types of funding used as follows: "Of the final budget of KRW 384 billion (USD 323 million) for the restoration, the municipality utilized KRW 100 billion (USD 84.13 million) that was initially assigned for the overall renovation of the elevated highway. It also saved some KRW 100.4 billion (USD 84.47 million) by downsizing less urgent projects and introducing creative work procedures to enhance the efficiency of the city administration. The rest of the budget was secured from the city's general accounting. Since the project was scheduled to be conducted from 2003 to 2005, KRW 130 billion (USD 109.3 million) was acquired for each year of construction, amounting to about one per cent of the municipality’s total budget".
Source(s) of funding
Public local authority budget
Type of fund(s) used
Earmarked public budget
Non-financial contribution
No
Business models
Risk reduction model
Green densification model
Which of the involved actors was motivated by this model?
Public actor (e.g. municipality)
Type of innovation
Social
Policy innovation
Please specify social innovation
Whilst "the decline of the old downtown area of Seoul was a persistent problem over the years...the Stream restoration idea was not included in the official urban planning documents because the idea was seen as too ambitious and beyond the imagination or capacity of the local government" (Ref. 8). Thus the Cheonggyecheon stream restoration arising as the then-Mayoral candidate of the time's "major campaign pledge" was seen as a political innovation (Ref. 8).
Novelty level of the innovation
Unknown
Please specify novelty level of the innovation
Unknown
Replicability/Transferability
Unknown
Please specify Replicability/Transferability
Unknown
Impacts, benefits
Environmental impacts
Climate change
Lowered local temperature
Reduced emissions
Environmental quality
Improved air quality
Water management and blue areas
Improved water quality
Increased protection against flooding
Improved stormwater management
Enhanced protection and restoration of freshwater ecosystems
Green space and habitat
Promotion of naturalistic styles of landscape design for urban development
Increased green space area
Increased number of protection areas
Increased conservation or restoration of ecosystems
Increased ecological connectivity across regeneration sites and scales
Increased number of species present
Description of environmental benefits
The stream restoration project resulted in:
- lowered local temperatures, reducing the heat island effect: "...with temperatures along the stream 3.3° to 5.9°C cooler than on a parallel road 4-7 blocks away. This results from the removal of the paved expressway, the cooling effect of the stream, increased vegetation, reduction in auto trips, and a 2.2-7.8% increase in wind speeds moving through the corridor" (Ref. 2);
- reduced emissions through indirect improvements in public transport connectivity, resulting in "15.1% increase in bus ridership and 3.3% in subway ridership in Seoul between 2003 and the end of 2008", and also by the NBS providing a green corridor for pedestrians and cyclists (Ref. 2);
- improved air quality, "Reduced small-particle air pollution by 35% from 74 to 48 micrograms per cubic meter. Before the restoration, residents of the area were more than twice as likely to suffer from respiratory disease as those in other parts of the city" (Ref. 2);
- improved water quality;
- increased protection against flooding through stormwater management, as the NBS "provides flood protection for up to a 200-year flood event and can sustain a flow rate of 118mm/hr" (Ref. 2);
- enhanced protection and restoration of freshwater ecosystems and promoted naturalistic styles of urban landscape design by "reestablish[ing] connections between waterways. The Cheonggyecheon eventually runs into Jungraechon stream, which leads out into the Han River", with the wetlands at their meeting point being designated as an ecological conservation area (Ref. 2);
- increased greenspace area by virtue of the 5.8km restored stream creating a "continuous east-west green corridor" (Ref. 2); and
- increased the restoration of ecosystems for local habitats and species; increased the number of species present and increased ecological connectivity with "native willow swamps, shallows and marshes [being] constructed in 29 different locations along with the restoration, creating habitat for fish, amphibians, insects, and birds" and "a fish spawning ground [being] created where the Cheonggyecheon and Jungnangcheon meet" (Ref. 2).

The current status of fish numbers and plants, including the results of an annual fish survey, can be accessed via Ref. 6.
Economic impacts
Increase of green jobs (e.g. paid employment positions)
More sustainable tourism
Increased property prices
Stimulate development in deprived areas
Reduce financial cost for urban management
Attraction of business and investment
Description of economic benefits
The stream restoration project:
- has been associated with an increase of jobs, stimulated development in an otherwise "declining" downtown area (Ref. 9) and increase attraction of business and investment, as summarised by Ref. 2: "Increased number of businesses by 3.5% in Cheonggyecheon area during 2002-2003, which was double the rate of business growth in downtown Seoul; increased the number of working people in the Cheonggyecheon area by 0.8%, versus a decrease in downtown Seoul of 2.6%";
- has been associated with an increase of an "average of 64,000 visitors daily. Of those, 1,408 are foreign tourists who contribute up to 2.1 billion won ($1.9 million USD) in visitor spending to the Seoul economy" (Ref. 2);
- has increased property prices in the area, to double the rate of property increases in other areas of Seoul, "Increased the price of land by 30-50% for properties within 50 meters of the restoration project" (Ref. 2); and
- has reduced the financial cost of urban management, as has offered an alternative to the required calculated costs of "100 billion won ($90 million USD) and 3 years of repairs to secure the safety of the ag[e]ing structure" of the Cheonggyecheon Expressway which the Cheonggyecheon Stream Restoration replaced (Ref. 2).
Social and cultural impacts
Social justice and cohesion
Improved access to urban green space
Health and wellbeing
Improved physical health
Gain in activities for recreation and exercise
Cultural heritage and sense of place
Improvement in people’s connection to nature
Protection of historic and cultural landscape / infrastructure
Education
Increased support for education and scientific research
Increased knowledge of locals about local nature
Description of social and cultural benefits
The Cheonggyecheon Stream Restoration has increased access to urban greenspace and offers places for recreation (Ref. 4). It has catalysed an improvement in air quality in an area which previously saw "residents of the area [be] more than twice as likely to suffer from respiratory disease as those in other parts of the city" (Ref. 2). It has further become "popular with residents and visitors alike for rest and relaxation" (Ref. 4).

The historical nature of the area is communicated via "national and imperial motifs [which] highlight this zone’s emphasis on history", with seating being installed "throughout to encourage the public to use the space" (Ref. 2). The restoration of historical relics was further emphasised during the restoration project as a whole, "the restoration work for the Cheonggyecheon is also associated with the effort to regain its pride as a nation with splendid traditional culture through restoring some historical objects" (Refs. 1 & 5).

The stream restoration has additionally provided educational support, improved people's connection to nature, and provided an opportunity to increase citizens' knowledge about local nature, particularly with "Schoolchildren hav[ing] access to a valuable educational resource through the ecology embedded seamlessly within their urban environment" (Ref. 4).
Type of reported impacts
Achieved impacts
Indicators
Localised air temperature, quality and wind speeds (Ref. 2); localised public transport usage (Ref. 2); water quality (biochemical oxygen demand and total phosphorous) (Ref. 6); number and type of local habitats, the current status of fish numbers and plants, including the results of an annual fish survey (average number of classes and species) (Ref. 6); number of local businesses and employment rate (Ref. 2); number of visitors (Ref. 2); increase in property prices in the adjacent area (Ref. 2); and reduced cost of alternative urban management plan versus annual maintenance of NBS (Refs. 2 and 6).
Analysis of specific impact categories
Job creation: The NBS created ...
other
Environmental justice: The implementation of the NBS project resulted in ...
Improved access to green and/or blue spaces
Please specify other method used to evaluate the impacts of NBS
Analysis of economic impacts including the number of local businesses and employment rate (Ref. 2); the number of visitors (Ref. 2); increase in property prices in the adjacent area (Ref. 2); and reduced cost of alternative urban management plan versus annual maintenance of NBS (Refs. 2 and 6).
Negative impacts: Did the project cause any problems or concerns?
Yes
Please specify the negative impacts
Lack of public consultation during the design process was considered to have resulted in underrepresentation of user groups, particularly so older people, people with visual impairments and people with mobility problems (Ref. 4). This has since been somewhat ameliorated, but as explained by Ref. 4 still has some shortcomings due to inclusive design not being comprehensively sought from the start.
COVID-19 pandemic
Unknown as of September of 2021
Methods of impact monitoring
Process of recording NBS impacts
Collection of monitoring data continuously throughout the project to aid evaluation
Collection of monitoring data at specific time intervals during the project to aid evaluation
Methods used to evaluate the impacts of NBS
Measurements of biophysical aspects of the NBS (e.g. temperature, water flow)
Observation (including virtual surveillance methods)
Other
Where can this data be accessed? Please include a link to a report or web-page.
https://www.landscapeperformance.org/sites/default/files/Cheonggycheon%20Method…
Evidence for use of assessment
Presence of an assessment, evaluation and/or monitoring process
Yes
Presence of indicators used in reporting
Yes
Presence of monitoring/evaluation reports
Yes
Link to monitoring/evaluation reports
https://www.sisul.or.kr/open_content/cheonggye/intro/animals.jsp
Availability of a web-based monitoring tool
No evidence in public records
Impact assessment mechanism
Name of any specific impact assessment tools
Unknown
Use of GIS in mapping impacts
No evidence in public records
Citizen involvement
Citizens involvement in assessment/evaluation
Unknown
Citizens involvement in the analysis of the assessment/evaluation
Unknown
Follow-up to the evaluation / assessment
Yes
Please specify
Although not arising through formal citizen involvement in the analysis of NBS impacts, it is worth noting that, as touched upon above, "limited consideration of certain user groups, for example, older people, people with visual impairments and people with mobility problems" resulted in a protest march occurring in September 2005, with "a group...demanding the right to access the new pathways alongside the stream. In response, lifts were provided at seven locations, together with free wheelchairs for users with mobility problems" (Ref. 4).
References
List of references
1. Seoul Metropolitan Facilities Management Corporation (2009). Cheong Gye Cheon History: Restoration. Seoul: Seoul Metropolitan Facilities Management Corporation. http://www.sisul.or.kr/grobal/cheonggye/eng/WebContent/index.html [accessed 16/09/21];
2. Landscape Architecture Foundation (no date). Cheonggyecheon Stream Restoration Project. Washington, DC: Landscape Performance Series. https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration#/overview [accessed 16/09/21];
3. Landscape Architecture Foundation (no date). Cheonggyecheon Stream Restoration Project: Methodology for Landscape Performance Benefits. Washington, DC: Landscape Performance Series. https://www.landscapeperformance.org/sites/default/files/Cheonggycheon%20Methodology.pdf [accessed 16/09/21];
4. Commission for Architecture and the Built Environment (no date). Cheonggyecheon Restoration Project. London: The National Archives. https://webarchive.nationalarchives.gov.uk/ukgwa/20110118101111/http://www.cabe.org.uk/case-studies/cheonggyecheon-restoration-project [accessed 16/09/21];
5. Jeongho, K, Keeyeon, H, Woonsoo, K (no date). Downtown Revitalization: Cheonggyecheon Restoration Project. Sejong City: Korea Development Institute School of Public Policy and Management, Kdevelopedia. https://www.kdevelopedia.org/Development-Topics/themes/--13 [accessed 16/09/21];
6. Seoul Metropolitan Facilities Management Corporation (no date). Cheonggyecheon Stream Overview. Seoul: Seoul Metropolitan Facilities Management Corporation. https://www.sisul.or.kr/open_content/cheonggye/intro/summary.jsp [accessed 16/09/21];
7. Gamesby, R (2020). River restoration and conservation in damaged urban catchments. Web Resource. https://www.coolgeography.co.uk/advanced/River_Restoration_Conservation.php [accessed 16/09/21];
8. The World Bank (no date). Case Studies: Seoul. Washington, DC: World Bank Group. https://urban-regeneration.worldbank.org/Seoul [accessed 17/09/21]; and
9. Seoul Solution (2011). Seoul Urban Regeneration: Cheonggyecheon Restoration and Downtown Revitalization. Seoul: Seoul Solution. https://www.seoulsolution.kr/en/content/seoul-urban-regeneration-cheonggyecheon-restoration-and-downtown-revitalization [accessed 17/09/21].
Comments and notes
Additional insights
Additionally, the number of bridges along the route of the restored stream were to be minimised "in order to transmit a maximum amount of water", with a total of 22 bridges being constructed, five of which were designated for pedestrians, the remaining 17 for motor vehicles (Refs. 5 & 6).
Public Images
Cheonggyecheon Before
Cheonggyecheon Freeway before the NBS intervention
https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration#/sustainable-features
Cheonggyecheon After
Cheonggyecheon Stream after the NBS intervention
https://www.landscapeperformance.org/case-study-briefs/cheonggyecheon-stream-restoration#/sustainable-features
Cheonggyecheon Before and After
Cheonggyecheon before the restoration (2001, left) and after the restoration (2005, right)
https://www.coolgeography.co.uk/advanced/River_Restoration_Conservation.php
Cheonggyecheon Stream as an NBS
Cheonggyecheon Stream as an NBS
https://urban-regeneration.worldbank.org/Seoul