Culverts typically carry flow in a natural stream or urban drainage channel under a road or railway. In some urban areas, the practice of culverting long lengths of a natural watercourse to gain space for urban development has traditionally been widespread. The practice is now generally recognized as having a negative impact on amenity and biodiversity. By reopening the culverts, these negative impacts can be reduced. In this way, the re-opened culverts can help manage stormwater and slowing down the flow of stormwater.

Culverts tend to increase flood risk, especially if they are either too narrow in diameter or become blocked by debris. An urban structure or development that has been facilitated by the routing of a natural stream within a culvert may be at risk of flooding from that same culvert. Compared with an open stream, access for maintenance of culverted watercourses is also limited. Reopening culverts (sometimes termed ‘daylighting’ or 'deculverting' ) can be part of the integration and enhancement of watercourses in urban areas, with benefits in terms of biodiversity, water quality and amenity as well as flood risk reduction.

An example of this approach is the elevated freeway constructed above the Cheonggyecheon River in Seoul, South Korea, in the early 1970s. At the time, it was considered a symbol of progress, but by the early 2000s, the Cheonggyecheon area was the most congested and noisy part of Seoul. A river restoration project was therefore initiated to remove the freeway and restore the stream. This was completed in 2005 and is considered a major success.

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