Green infrastructure protects against extreme weather and cleans up urban environments.
When a city incorporates natural infrastructure into its planning, it turns to living assets such as urban trees, wetlands, and watersheds to reduce pollutants and provide protection from storms and hurricanes. So effective is the strategy that the United States Conference of Mayors on Monday approved a resolution that encourages its 1,400 members to start building green bulwarks against climate change.
Philadelphia, for instance, already is using green infrastructure to manage its storm water challenges. Runoff from the city’s streets, parking lots, roofs, and playgrounds once triggered sewer overflows that inundated waterways with pathogens, debris, and other pollutants, and made rivers unsafe for swimming and boating after storms. The storm water also eroded riverbanks, uprooting vegetation and sending sediment into pools and to the bottom of streams, upsetting the habitat for fish and bugs.
The city has designed and constructed several blocks of porous streets and basketball courts made of permeable paving material that lets water pass through the surface to an underground stone reservoir before entering the soil—never becoming runoff. It also has trenches, planters, street bump-outs, rain gardens, and other natural features that have land acting like a sponge to slow down the flow of rainwater into the waterways and keep storm water out of the sewers.
