Why Cities are Investing in Natural Drainage Systems and Green Infrastructure 🌧️
The L.A. River is maybe one of the most famous examples of what we might call “vintage” drainage infrastructure. ~95% of the river is impervious surface. (https://www.circleofblue.org/2022/world/concrete-river-pollution-water-life-and-the-future-of-the-los-angeles-river/)
Urbanization brings with it the intensifying issue of outdated stormwater management. As traditional drainage systems are increasingly overwhelmed by heavier and more frequent rainfall events, humanity is turning to solutions that work with nature rather than against it.
Traditional Drainage Vs. Natural Drainage
Traditional drainage manages stormwater using impervious material like pipes, gutters, and storm sewers. These systems tend to consider stormwater as a baton to pass to an adjacent property, neighborhood, stream, river, city… they seek to displace stormwater quickly and discretely. They offer almost no opportunity for infiltration — which means more watershed pollution and higher flood risks. Natural drainage refers to systems that manage stormwater by promoting infiltration and mimicking the natural water cycle. These systems use features like swales, dry creeks, rain gardens, and retention ponds to slow, filter, and absorb runoff. Annually, this single CoFo rain garden/dry creek system is keeping thousands of gallons of rainwater from entering our sewer systems and waterways.
Why Opt In?
So beyond flood mitigation, why are these solutions the way to go? And why are government entities country-wide developing programs to install natural drainage?
Water Quality: These systems filter pollutants from runoff, improving the quality of water that eventually reaches rivers, lakes, and oceans. This green infrastructure is critical for protecting aquatic ecosystems and making our waterways safe. Philadelphia's Green City, Clean Waters (https://water.phila.gov/green-city/) program estimated “nearly three billion gallons of stormwater runoff and sewer overflow out of local waterways” within the last decade of green infrastructure changes.
Reduced Costs: Although these systems require maintenance, they often involve less costly and more sustainable practices than the upkeep of traditional concrete and pipe networks. Underground and impervious mechanisms of drainage are inherently more difficult to access and maintain. * Cooling the City: Vegetated drainage solutions help mitigate the urban heat island effect by cooling the air through evapotranspiration. This cooling effect can reduce the need for energy-intensive air conditioning, lowering urban energy consumption and greenhouse gas emissions.
Ecosystem Support: Natural drainage projects often double as habitats for wildlife. They can provide critical refuge for birds, insects, and other wildlife living in highly fragmented urban settings.
Enhanced Public Spaces: Something we at CoFo especially take pride in is the fact that natural drainage will beautify our urban areas. Cities are also recognizing it as an opportunity to create green spaces that enhance community well-being.
It’s hard work undoing impervious surfaces! Take it from us… this is yesterday’s project, pulling up a backyard concrete pad. This is both reclaiming green space AND increasing infiltration.
What About Atlanta?
Many of our readers are from Atlanta, so you may be curious what our city is up to? Atlanta’s flooding is not news to anyone living here and our government is actualizing endeavors for natural mitigation. Their green infrastructure task force is partnered with many organizations to push their projects. You can learn more here. (https://www.atlantawatershed.org/greeninfrastructure/) At CoFo, we believe that conservation — whether it involves reducing pollutants in our waterways, planting habitats for pollinators, or managing invasive species in our landscapes — shouldn't be left solely to our governments. It's up to all of us to take action, using whatever space we have.