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Construction Corner: New floodplain guidelines a must for mitigation measures

Korky Koroluk
Construction Corner: New floodplain guidelines a must for mitigation measures
Korky Koroluk

March is an uncomfortable time of year.

Spring should arrive any day now, but we’re wary.

What if spring is just a cruel joke?

It’s a time of year when people start measuring snow packs, trying to determine whether they’re going to be flooded or not.

That’s especially true in Winnipeg, where the Red River chooses to misbehave often enough that local residents are edgy about the possibility every year. I was talking to someone in Winnipeg a few days ago, though, who told me the warm stretch in February melted enough snow that the flood worries melted along with it. Maybe.

Flooding is not just a spring phenomenon. Ask the folks in Calgary and High River, Alta., who got walloped by an early June flood in 2013. Or in Saguenay, Que., who got hit in July of 1996. Hurricane Hazel caught Toronto off guard on Oct. 15, 1954.

There have been many others of course. As we get more severe storms in our warming climate there will be more of them.

In Canada, federal, provincial and municipal governments are all involved in flood management one way or another.

It’s up to the feds to ensure a broadly consistent national approach to flood mitigation and to ensure that basic mapping requirements are met. Provincial governments are responsible for funding and implementation of mitigation measures for entire watersheds, administration of disaster-recovery funding and regulation of the insurance industry. Municipalities and provinces share responsibility for water management, emergency management, land-use planning and zoning and the design of critical infrastructure. The actual construction is a municipal concern.

That’s why it was nice to see the release, just a few days ago, of the first in what will be a series of guidelines on floodplain mapping.

This first publication deals only with the framework needed for mapping. Coming up this spring are four more, dealing with things like hydrologic and hydraulic procedures for delineating floodplains, geomatic guidelines for mapping, even a collection of best practices and references for flood mitigation.

These aren’t one-off publications. All are intended to be what Natural Resources Canada (NRCan) calls "evergreen," which is to say they will be adapted as new technological and scientific developments emerge.

The guides are aimed at a diverse audience: infrastructure providers, water managers, hydrologists, town planners, hydraulic engineers and quite a few others in both the public and private sectors. Municipal engineers will be reading them. So will some of the contractors who build sewers and watermains and treatment plants, which are sometimes inundated when flooding occurs.

The introduction to the first of these notes that floods "are the most commonly occurring natural hazard in Canada and account for the largest portion of disaster-recovery costs."

It follows then that mitigating flood risks is key to increasing the resilience of many of our communities.

"By proactively investing in flood mitigation activities, a community secures practical investments for its future growth and prosperity, reducing the risk of significant disaster-recovery costs, productivity losses, economic losses, destruction of non-monetary cultural assets, environmental damage, injuries and deaths," it reads.

Taken together, the documents are intended to give details on technical aspects of:

• hydrologic and hydraulic investigation;

• floodplain mapping;

• risk assessment;

• determining the effects of climate change on flood modelling;

• LiDAR (laser-based) data acquisition; and

• land-use planning.

Looking at the list of responsibilities, I’m struck by how many people need to be in touch with each other as the likelihood of flooding increases. And it’s not just Canadian officials.

Floodwaters are no respecters of boundaries, which means that provinces have to co-operate. In the case of Manitoba’s Red River, which flows north, the flood-watchers in Manitoba have to be in touch with their opposite numbers in North Dakota and Minnesota and maybe even volunteer to send them a copy of this new framework document.

The document can be downloaded from NRCan at

Korky Koroluk is an Ottawa-based freelance writer. Send comments to

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