How Seoul and Zürich Are Bringing Buried City Streams Back to the Surface

Many cities buried natural streams underground during rapid development, but new research argues that bringing them back to the surface — a practice called stream daylighting — could help manage the heavy rainfall and aging infrastructure many cities now face. Restoring buried streams can ease stormwater flooding, rebuild wildlife habitat and create walkable green space, according to research comparing projects in Seoul, South Korea, and Zürich, Switzerland.

Between 2003 and 2005, Seoul restored the Cheonggyecheon stream by removing an elevated highway and rebuilding one major downtown corridor as a single, centralized project, linking it to public transit, cycling paths and pedestrian bridges. The project required heavy capital investment and ongoing maintenance, and critics have questioned its ecological value because pumps supply water to the channel; nearby redevelopment also raised land values and displaced some smaller businesses.

Zürich took a different route. Since pilot projects began in the 1980s under a program the city calls its stream concept, Zürich has restored many smaller stream segments over several decades, tying each one to sewer management, infrastructure renewal and neighborhood planning. No single Zürich project has Seoul's high profile, but together they form a distributed network of paths, bridges and public spaces that improves the watershed and gives more neighborhoods access to water.

The research recommends that municipalities start not with construction but with mapping: combining culvert inventories and historical watercourse maps with data on flood risk, heat risk and social vulnerability. In Toronto, researchers found that flood exposure intersects with social vulnerability in neighborhoods such as Black Creek and Flemingdon Park, though the city has not yet set clear priorities for restoring its buried streams there.

In Vancouver, restoration of Still Creek has unfolded gradually over more than two decades through a mix of municipal investment and private redevelopment, including a developer-funded daylighting project completed in 2009, with local community groups now monitoring returning salmon.