Significant risks remain but Calgary says it's in a good position for flooding

Nearly five years after devastating flooding southern Alberta, Calgary says there’s work to be done but it’s in a good position for what might come.

It's been almost five years since floodwaters spilled the banks of the Bow and Elbow rivers

CBC News · Posted: May 14, 2018 2:09 PM EDT | Last Updated: May 14, 2018

Southern Alberta, including Calgary, was hit with massive flooding in June 2013. (Andy Clark/Reuters)

Nearly five years after devastating flooding in southern Alberta, Calgary says there's work to be done but it's in a good position for what might come.

"There remains significant risk," Frank Frigo, watershed analysis leader, told reporters Monday afternoon.

"Right now, we have a forecast window of about 10 days with the models we use to look at what's coming. We are seeing very rapid depletion of the above-average snowpack this past winter. We are seeing about 25 to 50 mm of snowpack come off each day. That is driving flows that are well above seasonal."

Faster rivers

Both the Bow and Elbow rivers are flowing much faster than normal.

"The Bow River today flows through Calgary at about 200 cubic metres per second, whereas the normal flow at this time of year would be about 70 cubic metres per second," he said.

The Elbow is flowing at about nine to 10 cubic metres per second compared with its normal seven.

He said individual preparation, which can be helped with the city's online assistance, is critical.

"Understanding the risk in your community is very key to knowing what you may need to do," Frigo said.

Frank Frigo, Calgary watershed analysis leader, says there is still a lot of flood mitigation work to do. (CBC)

Ask yourself some questions

For those homes and businesses near rivers, ask yourself some questions.

"What kinds of documents and valuables are you storing in the lower floors of your dwellings? If you are operating a business, what kind of operations do you have going on in the lower floors and how can you modify that during this period to ensure you have a plan to respond."

And a 72-hour kit is important to think about right now.

"Where you would go, who you would contact, what things you would bring and how you would prepare to be able to re-enter after an event."

$70-80M of investment still needed

Following the 2013 flooding, six key areas were identified including 27 core recommendations, from large to local in scale, and there's still roughly $70-80 million of investment needed.

"All of them are in the works, at some level of completion," Frigo said.

"Obviously some of the pieces will take longer than a season or two to put in place."

This year, however, snowmelt has been co-operating.

"Unlike the overland flooding that we saw in much of Central Alberta through the early spring, that snowmelt mechanism in the mountains is much slower," Frigo said.

"In general, it is not snowmelt that drives river flooding in Calgary, it is large precipitation events in combination with elevated background conditions from the snow. We are tracking an event that will move into southern Alberta sometime late Wednesday or Thursday which could bring 25 to 30 mm of precipitation. It's manageable, though."

Some reservoirs lowered

The Ghost Reservoir has been lowered to its pre-flood level and work being done on the Glenmore Reservoir has required lowering its levels, which has further assisted the city in preparation.

"The technical tools that give us the feedback, vital signs, have improved," he said.

However, Calgary still remains at a disadvantage in forecasting.

"Our response times tend to be in the order of hours."

On the Elbow, the city should be protected from overland flooding once a dry dam is built in Springbank and a major renovation of the Glenmore Dam is completed. And the work, he says, continues.

"There remain a number of very important projects along the Bow River that need to be completed to bring the level of resilience in the city up," Frigo said.

Calgary's flood season runs May 15 to July 15.