Greening Our Grey Cities

Many cities around the world are turning to green infrastructural solutions to enhance resilience to climate change while creating livable spaces for their residents.

By Robert C. Brears

Green infrastructure involves the use of natural or semi-natural systems that utilize nature’s ecosystem services in the management of water resources and associated risks. Green infrastructure solutions can be used to support the goals of multiple policy areas. For example, floodplains can reduce flooding risks to cities while simultaneously supporting agricultural production, wildlife, and providing recreational and tourism benefits. Unlike grey infrastructure, the value of green infrastructure solutions can appreciate over time with the regeneration of nature and its associated ecosystem services.

Oslo restoring its nature

Oslo has 10 main waterways that run through its urban areas. Up until recently, the city’s waterways were considered problematic for sewage and an obstacle to the development of land. As such, large sections of waterways flow through pipes and culverts. However, these have predefined capacities and with more frequent and heavier rainfall from climate change, urban flooding will become an increasing challenge. Oslo has decided to restore its waterways by reopening closed rivers and streams where possible to handle stormwater more efficiently, as well as create recreational spaces for people and facilitate increased habitat for biodiversity. One example is the Teglverksdammen Project which is a reopening of around 650 meters of the stream Hovinbekke. The project has been planned and designed as a natural cleaning system with several sedimentation basins, a stream with water rapids, a small lake, and shallow waters with dense vegetation. Stormwater from a nearby school is also safely led into the newly reopened stream.

Vancouver’s green future

In Vancouver, over half the city is made up of impervious surfaces resulting in runoff carrying pollutants into local waterways as well as overwhelming the combined sewer system during heavy rainfall periods. Vancouver’s goal is to capture and treat 90% of its average annual rainfall by using green infrastructure practices on both public and private land. One project contributing towards this target is the 63rd Avenue and Yukon Street Boulevard Improvements project which has been identified as an opportunity to increase access to green space, enhance rainwater management, and improve neighborhood amenities. The boulevard will feature sidewalks, seating plazas, bike racks, a drinking water fountain, and lush rain garden beds that will contribute to cooling down the surrounding area during extreme heat and provide clean water, air, and lush nature in urban spaces for the community and nature.

Conclusion

Green infrastructure helps cities simultaneously enhance water quality, build resilience to climate change, and restore the natural environment.

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