How much money is a cattail worth? What about a water lily? Or an acre of wetland?
Until now, ecologists have touted less quantifiable benefits of wetlands: they perform a vital role in Ontario’s ecosystems, filtering rainwater and providing habitat for a huge variety of species, including some that are endangered and at-risk.
But a study released Wednesday by the Intact Centre on Climate Adaptation at the University of Waterloo has pegged a dollar value to wetlands, based on how much flood damage they help prevent. Wetlands’ spongy earth and dense plant life slow down surging floodwaters and can dramatically reduce the amount of water that makes it into your basement.
“These things aren’t decoration. They actually serve a function, and when we develop them we should recognize that we’re losing the flood attenuation capacity that goes with them,” says Blair Feltmate, director of the Intact Centre.
Southern Ontario has destroyed 72 per cent of its wetlands overall, and up to 95 per cent in some built-up areas. But the agricultural and urban developments they’re so often replaced with don’t have the same absorptive capacity. And as Ontario grapples with catastrophic flooding in the Great Lakes region this year, that capacity seems increasingly important.
The Waterloo study compared detailed models of two areas, one urban and one rural, and calculated the amount of damage that severe flooding would cause in each based on surrounding wetland coverage.
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The rural model, which used satellite data from a site outside Mississauga, predicted $8.9 million in flood damage with the wetland intact. When the wetland was replaced with agricultural land, the projected cost was $12.4 million. The urban model, involving an area in Waterloo, projected $84.5 million in damage with the wetlands, $135.6 million without.
“With the multitude of flood events occurring, losing these wetlands on a regular basis is adding cost to the amount of damage realized due to high intensity storm event,” Feltmate says. “We’ve always known they've served a role in mitigating flood risk, but we didn't know the degree of the role they played. Now we know it’s quite substantial.”
Ducks Unlimited, a conservation group that supported the study, wants the provincial government to view wetlands as an infrastructural concern rather than an environmental one.
“It’s a more holistic approach to planning at the municipal, federal, and provincial level. We put all of our investment into hard infrastructure, which has a huge cost and a huge maintenance bill,” says Lynette Mader, a manager at Ducks Unlimited. “If we can start to incorporate green infrastructure planning — natural infrastructure — into our planning processes, it can help reduce the need, increase the life cycle, and reduce costs.”
Mader says the cost study was the last of a three-part effort to promote the idea of wetlands as a form of infrastructure that can help alleviate catastrophic flooding. (First was a literature review confirming that, in theory, wetlands slow floodwaters. Second was extensive modelling intended to determine whether and how they do so.)
The estimate puts a number to what was once just a notion, and provides a financial, as well as ecological, incentive to save Ontario’s wetlands — which will require freeing up land and paying for remediation and rehabilitation. In other words, money.
“What we’re trying to understand is how much we need now for Ontario to be climate change resilient. That needs to be understood on a watershed basis,” Mader says. “We need to be investing in them in the same way we invest in our hard infrastructure.”
Photo courtesy of one.juniper and licensed for commercial use under a Creative Commons licence. (See the uncropped version.)
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