Image via the Stormwater Guidance Retrofit Manual courtesy of Philadelphia Water |
Urbanization has altered the natural landscape and affected the hydrologic cycle. Where the natural hydrologic cycle maintains a balance of water circulation through evaporation, precipitation and groundwater recharge, and absorption and transpiration by plants, urbanization has resulted in an altered hydrologic cycle through construction of impervious surfaces such as buildings, roads, and parking lots.
The water has nowhere to go except into a city's seemingly endless configuration sewer pipes, systems which are becoming increasingly overburdened and thus prone to overflows and outfalls of polluted runoff into watersheds, such as rivers, lakes and creeks during heavy rains.
In urban areas with combined sewer systems, such as Philadelphia, Chicago and New York, the impact is can be particularly troublesome because the discharges, known as CSOs or combined sewer overflows, often contain untreated sewage.
Green stormwater infrastructure is an incremental, ecologically centered, low impact development approach to mitigate these outfalls by reducing the amount of runoff that goes to the sewer system and by utilizing the water as a resource, via rain gardens, tree trenches, permeable paving, rain barrels, green roofs and more.
Because of its incremental approach, the implementation cost for cities is often much less than heavily engineered concrete gray infrastructure efforts. It may not be the sole solution, but it offers a plethora of benefits measured in more ways than just pollution prevention. Benefits such as awakening the urban ecosystem through tree planting and stream restoration, bringing together local communities over health and environment issues, and spawning a thriving new "green collar" workforce that offers opportunity to urban areas left buried in the ruins of the industrial age.
The NatureWORKS report by Jobs For the Future, jff.org, for example, contends that "in urban green infrastructure, there is an opportunity for entry-level jobs with the possibility for advancement. It is a win-win for cities to invest in sustainability and achieve both a healthier, greener community and a job development program."
Other efforts, such as with the Great Urban Parks Campaign, the National Recreation and Parks Association and the American Planning Association are also working to demonstrate the benefits of green infrastructure in urban communities. Their video below states that "using parks for green infrastructure is a creative and cost-effective alternative to gray infrastructure that allows nature to filter pollutants from rain water, reduce storm water issues and give communities access to more green space."
The NatureWORKS report is available for download in PDF at the following link: https://jfforg-prod-prime.s3.amazonaws.com/media/documents/NatureWORKS-Issue-Brief-032317_v3.pdf
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