A water expert says heavy rainfall forecast for southern Alberta could cause damage in some areas, prompting Calgary to declare a local state of emergency, but it doesn’t appear as if a repeat of deadly flooding in 2013 is coming.
John Pomeroy, a University of Saskatchewan hydrologist and Canada Research Chair in water resources and climate change, said there’s an interesting combination of events taking place.
“We have a very high mountain snowpack for this time of year — one of the highest in decades — and that’s because of high winter snowfall and a very cool spring,” Pomeroy said in an interview from Canmore, Alta., on Monday. “Then we have a very high forecast of precipitation for the mountains and foothills.”
Environment Canada has issued rainfall warnings for between 75 millimetres and 150 millimetres of rain by Wednesday morning in parts of Alberta, including Banff, Calgary and Rocky Mountain House.
Alberta Environment has also issued flood warnings on the Highwood River and in the Red Deer River basin. A flood warning on the Bow River between Banff and Exshaw has been downgraded to a watch and there are still flood watches in effect on the Bow and Elbow rivers upstream of Calgary and High River.
Both communities were hit hard during flooding in 2013 which left at least five people dead and caused billions of dollars in damage across southern Alberta.
“I know this is a tense time for many Albertans,” said Environment Minister Jason Nixon. “This is especially true for communities that were at the centre of the devastating 2013 floods.
“Please know Alberta is better prepared than ever for high-river events.”
The province, he said, has updated its flood mapping and municipal governments are prepared to deal with any flooding.
Calgary has issued a high stream flow advisory on both the Elbow and Bow rivers and water levels have been lowered in upstream reservoirs to make room for potential floodwater.
The city also declared the state of local emergency late Monday afternoon.
“I realize that may cause some fears, some anxieties for Calgarians, especially those who went through this in 2013,” said Mayor Jyoti Gondek.
The state of emergency, she said, will allow police and firefighters to go door-to-door to advise people they may be under an evacuation order if that becomes necessary.
Gondek said, however, that river levels are significantly lower than they were in 2013.
“This is out of extreme caution that we are doing this today,” she said.
Pomeroy said earlier in the day that people should keep a close eye on the forecast, but he noted that precipitation is currently expected to fall as snow rather than rain in the high mountains.
“So far … this appears to be a colder system than it was in 2013,” he said. “It would build up the snowpack instead of forming rapid runoff down to the creeks.
“But there’s always a lot of uncertainty with that — it depends on getting the air temperature within one or two degrees exactly right, so it could be wrong.”
Pomeroy said much would depend on what happened Monday night and Tuesday morning.
“From everything I can see, it doesn’t look like it will be a 2013-type event, though there’s still a possibility of damaging floods in localized areas,” he said.
Pomeroy added that towns and cities are much more prepared this year than they were nine years ago.
“We’re in a vastly better situation,” he said. “The preparations have been very good to lower reservoirs … berms are higher in many of the towns and cities. Some of the at-risk neighbourhoods, such as in High River, have been removed and are able to store water now.
“So, the ability to manage this flood — should it occur — is much better than it was in 2013.”
Saskatchewan’s water security agency said in a news release that it is also monitoring the rainfall warnings in Alberta.
“While the full impact of this weather system is not yet known, it will affect one or more of the major subbasins contributing to the South and North Saskatchewan rivers,” said the agency.
Both rivers, it said, will see higher stream flows later this week and levels at Lake Diefenbaker will also increase.
This report by The Canadian Press was first published June 13, 2022.
– Colette Derworiz, The Canadian Press