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How do we prevent the future devastation of Calgary flooding?

When the Bow and Elbow rivers rose higher and spilled deeper into Calgary than had been seen in a lifetime, the immediate question on many people’s minds was: How could this happen?

As the city transitions from flood relief to flood recovery, the pressing question will likely shift, as well. Many Calgarians will now be wondering: How can we make sure this doesn’t happen again?

Calgary – and southern Alberta in general – is not the first jurisdiction to grapple with this question in the aftermath of a devastating flood. Southern Manitoba went through a similar process after the flood of 1950 wiped out 10,000 homes in Winnipeg. So too did the Netherlands, after an enormous flood in 1953 that killed more than 1,800 people.

In response, Manitobans built the Floodway, a massive diversion of the Red River around the province’s capital and most populous city. The Dutch, meanwhile, developed the Delta Works, a complex system of dikes, storm-surge barriers and channels.

Decades later, these flood-protection measures were nearly overwhelmed by even more severe high-water events. The Netherlands experienced extensive river flooding in 1993 and then again in 1995, while Winnipeg literally came within inches of a catastrophe during the “Flood of the Century” in 1997.

Shortly thereafter, both jurisdictions undertook new projects to bolster their flood protection further.

Manitoba more than doubled the capacity of the Floodway, boosting its capacity to 4,000 cubic metres per second and offering 1-in-700-year protection. The project cost $665 million.

Faced with more complex geography and greater urban development, the Netherlands undertook a more complicated plan called the Room For The River Program, which consists of nearly three dozen small to medium-sized projects along the Rhine, Meuse, Waal, and Ijssel rivers. The $3.1-billion undertaking will ensure up to 1-in-10,000-year flood protection in some areas, according to project manager Hans Brouwer, who said the Dutch take their projects to a level that may seem excessive to North Americans.

“American journalists ask us: ‘Why do you protect for 1 in 10,000? That’s ridiculous,’ But the answer is, if you see what you have to invest … and you compare that with the damage you avoid in terms of lives and in terms of economy, then it’s well worth it to do so,” Brouwer said.

Manitoba Premier Greg Selinger holds a similar view.

“I think history has proven that these investments pay off,” he said. “Every dollar we have invested has protected us from about $30 in damage.”

Other jurisdictions have done the economic math, however, and come to different conclusions, according to Jerry Osborn, a professor of geoscience at the University of Calgary.

"It’s an interesting economic trade,” he said. “And, in some cases, I know they've decided the expense of a dam or other solution to do flood control for a big city is not worth it." And while the damage from Calgary’s flood is still being added up, Osborn thinks final tally will far outweigh the cost of similar flood protection measures here.

Initial estimates peg damage to city-owned assets alone as high as $500 million, and private losses are projected to be in the billions.

“I'm sure you could build a number of dams for $3 billion,” Osborn said.  The trick, he noted, is figuring out exactly what kinds of additional flood-protection measures would work best for southern Alberta.

That remains a difficult and open question, one to which neither the municipal nor provincial government could immediately provide a detailed answer.

“I've got some ideas on things we need to do around prevention and mitigation,” Mayor Naheed Nenshi said, but he declined to get into specifics.

Alberta environment minister Diana McQueen, meanwhile, replied with a written statement saying, “we will continue to find new and better ways to prepare for and mitigate the impacts of severe flooding.” Again, no specifics.

The issue does appear to be on the radar screen however – and not just because of the latest flood.

In mid-June the city issued a request for proposals, “seeking a qualified consulting firm to conduct a study of conceptual design options for permanent river flood protection structures within Calgary.”

Ironically, the initial response deadline had to be extended as city hall found itself under water a short time later. Proposals are now being accepted until Aug. 15.

‘Undevelopment’ another option when flood protection isn’t feasible

When protecting developed areas from flood or other natural disasters is too costly or difficult, another option is “undeveloping” high-risk zones.

“This is what they do in California and other jurisdictions for landslides," said Osborn. “The government actually buys up the front row of houses and as the slope gradually moves back with little landslide events, the front row of houses moves back with it."

While this option depends heavily on economics, politics, and attitudes surrounding who should bear the brunt of costs associated with flood mitigation, Osborn said it’s “something to consider” in Calgary.

Even after undertaking major flood-protection projects, the Manitoba government opted for this approach in some areas after the major flood of 1997 and again in 2009.

“It just made sense,” said Manitoba Infrastructure Minister Steve Ashton, adding that the homes the province bought up were in “chronically flooded areas” and “just couldn’t feasibly be protected.”

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