Natural Infrastructure

Lake Ontario and the Greater Golden Horseshoe are grappling with climate change made real by flooding, and made worse by all that rain-resistant pavement and concrete. Disruption of daily life, emergency services delay skyrocketing insurance rates: flooding affects everyone.

But there’s hope. Natural infrastructure — natural ponds and forests, de-paving, green roofs, rain barrels and more — can lessen the effects of flooding and increased rain. Effectively, And many solutions are just a shovel and a buddy away.

Grey to Green

Infrastructure is the basic equipment and structures (roads, bridges, buildings, water lines and sewer systems) that help functional, healthy communities run well. It must be maintained, repaired or replaced at the end of life-cycles. And because stormwater runoff has become a leading cause of water pollution in urban environments, community decision-makers must decide how to best manage it.

Traditional or “grey” stormwater infrastructure — curbs, gutters, drains, piping, and collection systems — typically collects stormwater from impervious surfaces, such as roadways, parking lots and rooftops, conveying it away from the built environment into piping that discharges the untreated stormwater into a local water body.

Natural or “green” stormwater infrastructure mimics nature, capturing and absorbing rainwater where it falls, reducing and treating stormwater at its source, while providing many other benefits to communities and residents:

• Reducing localized flooding
• Improving community aesthetics
• Encouraging neighbourhood socialization
• Increasing property values
• Decreasing the economic and community impacts of flooding




Control Nature, Or Let It Do Its Thing

The choice also comes down to this: make the infrastructure try to control nature, or let it use its own natural processes to design solutions.

In a natural system, stormwater does not travel at length without soaking into the ground. With grey infrastructure, stormwater may travel a long way over impermeable surfaces before it reaches a river, lake or sea — by which time it has picked up untold pollutants, toxins and dangers like E. coli, harmful to both humans and animals.

With grey infrastructure, when stormwater has nowhere natural to go and seep into, the water often has no choice but to head toward a destination that can’t handle the volume, such as sewers, which then overflow and pollute the environment.

Natural infrastructure, on the other hand, has elements that allow water to soak into the ground, filtering pollutants naturally. It retains or detains water just as nature does, keeping it roughly in place when it falls, instead of funnelling it onward.

Many experts believe the situation in Ontario will only worsen, including the Environmental Commissioner of Ontario. In a 2016 report, it stated: “Inadequate funding has created a $6.8 billion stormwater infrastructure deficit in Ontario. This financial gap could get even bigger in the future as population growth leads to the creation of more impermeable surfaces and, consequently, worsens runoff.”

For so many reasons, natural is simply better. And cheaper, too.

david philips

“We’re still on the same old infrastructure that our parents used, from the ’50s, ’60s and ’70s. That raindrop that falls on a very dry Hamilton or a very dry Toronto becomes a flood drop, because it falls on a hard surface.”

Dave Phillips
Senior Climatologist, Environment Canada

Unflooding Ontario with Natural Infrastructure

Natural infrastructure consists of the natural vegetative systems and green technologies that collectively provide society with a multitude of economic, environmental and social benefits. Examples include:

• urban forests and woodlots
• bioswales, engineered wetlands and stormwater ponds
• wetlands, ravines, waterways and riparian zones
• meadows and agricultural lands
• green roofs and green walls
• urban agriculture
• parks, gardens and grassed areas

It also includes technologies like porous pavements, rain barrels and cisterns, which are typically part of natural infrastructure support systems. The technologies replicate the functions of ecosystems, such as stormwater storage and filtration.

Saving A Lot Of Green

Natural infrastructure is a notably cost-effective way to reduce the flow and volume of storm-water that could otherwise lead to flooding. A few examples:

  • A 250-metre naturalized channel in Oakville, Ontario provides $1.24 to $1.44 million of stormwater conveyance and storage every year
  • Naturally occurring wetlands in southern Ontario reduce flood damage costs to buildings by $3.5 million (29%) at a rural pilot site, and $51.1 million (38%) at an urban pilot site 
  • Naturally occurring ponds in the coastal town of Gibsons, British Columbia provide $3.5 to $4 million of storm water storage services annually
  • A restored and engineered wetland in Manitoba is valued at $3.7 million for the flood reduction, water quality improvement, carbon sequestration and other benefits it provides

Other benefits typically not seen with traditional grey-engineered solutions include:

  • Storm water ponds help attenuate flooding, create aquatic habitats, improve biodiversity and provide aesthetic benefits
  • Green roofs provide habitat, cool the building and can produce food
  • Trees soak up literally tons of water and provide shade, beauty and habitat

A stormwater storage tank simply can’t do these things.