By: Nikki Kroetsch
Take a moment to think about the town or city you live in; how many streets there are, how many people live there, how many cars are driving around, and then how many contaminants make their way onto streets and sidewalks as a result of all this activity. The next time you take a walk, take notice of the things you see on the ground; the rainbow spots of oil in a puddle, the cigarette butts. When stormwater runoff carries these things away, where do they go? Is there a drain in the ground? Where does it go? Does the water get treated before it gets put back into a natural body of water, or does it flow directly in, untreated?
Stormwater runoff is water that falls as precipitation and then flows along the ground. If the ground is permeable, meaning water can flow through it, then the stormwater will seep into the ground. Examples of naturally permeable surfaces include soil, gravel, and sand. If the ground is impermeable, meaning water cannot flow through it, then water will flow along the surface until it reaches permeable ground, a stream or other body of water, or is directed into a pipe that connects to a stormwater system. Impermeable surfaces include asphalt and concrete. You’ve likely seen this if you’ve walked in an urban area on a rainy day; the water hits the ground and then flows along the pavement like a miniature river into man-made storm drains. Conventional stormwater systems, or “grey infrastructure”, are usually a network of pipes under the ground that direct water to a treatment plant or into a nearby body of water.
Stormwater management isn’t something people think about in their day-to-day lives, but it’s important for humans (especially in rainy areas prone to flooding) as well as fish and other species that live in urban, freshwater ecosystems. Urban flooding occurs when there is more water flowing along the surface than the stormwater management system can handle. Pipes designed to manage stormwater can only hold a certain amount of water, and anything more will continue to flow along the surface. Climate change is contributing to more frequent, intense rain events in many regions around the world, which overwhelm conventional stormwater systems and have contributed to increased flooding events. We’ve recently seen the devastating effects of these rainfall events in Fort McMurray, Alberta. Flooding is extremely destructive and expensive, as I’m sure you can imagine! Major floods can cause billions of dollars in damage, destroy people’s homes and properties, and can harm or kill people who aren’t able to flee in time.
Stormwater runoff also impacts the health of freshwater ecosystems, and everything that lives in them. This is because stormwater is often directed so that it flows directly into urban streams, taking oil, gas, litter, pesticides, brake residue from vehicles, etc. with it. All of this turns the stream water into a toxic soup that can harm or kill the species living in it, and then this contaminated water continues to make its way to the ocean.
Luckily, there is an increasingly popular, creative solution to stormwater management that has the potential to reduce flooding risk and keep urban streams clean: Green Infrastructure. Green Infrastructure is the use of natural features and “green technology” to manage stormwater, and it comes with a suite of other benefits. An example of Green Infrastructure is urban forests, small patches of forests that exist in urban areas. The soil on the forest floor is permeable, so the trees can take up the water from the soil. During heavy rainfall events, this small piece of land acts like a natural sponge, absorbing some of the water that could otherwise contribute to flooding. Green Infrastructure uses nature to slow the flow of water and allow some of it to flow back into the ground (and replenish aquifers). Another fantastic example of Green Infrastructure is rain gardens. Rain gardens contain native shrubs, grasses, and other plants and can hold stormwater runoff, giving water time to sink into the soil. Rain gardens not only reduce the risk of flooding, they also naturally filter water, meaning that the contaminants and litter get filtered out before entering any neighbouring freshwater ecosystems.
Now I know what you’re thinking: That’s fantastic, Green Infrastructure sounds so cool! But wait, there’s more! In addition to helping manage stormwater runoff by preventing flooding and filtering out contaminants, Green Infrastructure also provides habitat for birds, pollinators, and other species; can provide recreational opportunities for people (morning jogs in urban forests are the best!); can help to keep cities cool in the summer (trees and other vegetation help reduce the “Urban Heat Island Effect”); and can contribute to improved health and wellness for urban residents (e.g., trees filter out air pollutants and time spent in or near nature can help reduce stress and anxiety).
The best part about Green Infrastructure, in my opinion, is that it can be incorporated at all scales, from individual homeowner to governments at every level. Governments can contribute to larger projects, such as bioswales and urban wetlands, but as a homeowner one can install a green-roof or maintain a yard that contains natural shrubs and permeable surfaces, rather than paving over large sections of the property. Doing so incorporates Green Infrastructure and contributes to improved stormwater management and water quality for adjacent freshwater ecosystems.
In contrast to conventional grey infrastructure, Green Infrastructure is a perfect example of how working with nature is a way better option than working against nature. With its promises of effective stormwater management, reduced long-term costs, improved water quality, and a suite of positive externalities, Green Infrastructure is undoubtedly the way of the future when it comes to stormwater management.
For more information about:
Rain gardens: https://www.groundwater.org/action/home/raingardens.html
About the author:
Masters of Resource and Environmental Management Planning Candidate, Simon Fraser University
Nikki is an advocate for environmental conservation who believes that every person has the ability to make small changes that positivity impact their local ecosystems, which collectively results in big impacts. She completed a Bachelor of Arts Geography, majoring in Environmental Studies and minoring in Biology, from Simon Fraser University (SFU) in 2018 and is currently working towards a Masters in Resource and Environmental Management Planning degree, also at SFU. Her education, coupled with a life spent exploring land and sea in southwestern British Columbia, continues to motivate Nikki to encourage and inspire others to take the necessary steps to protect our great Earth and all the species that call it home.