The Red River spring freshet is now expected to approach the volume of the 2009 flood, which was the highest since the 1997 flood this century, according to provincial forecasters.
Provincial hydrologist Fisaha Unduche predicts the Red River will peak around May 10 at slightly lower levels than the 2009 flood, which closed Highway 75 for weeks and required the evacuation of some rural properties. .
Under favorable conditions, the crest this spring will be somewhere between the floods of 2011 and 2009. In the worst case, the flood could be even higher than in 2009.
Under all three scenarios, the volume of water from this year’s flood is expected to exceed that of the 2009 flood, but water levels will not be as high because ice on the river in 2009 caused the water levels, Unduche said.
Peak levels this year are not expected to be as high as all the ice has retreated from the river, especially in Winnipeg, which is protected by the Red River Floodway, he said.
Nonetheless, a flood on the order of 2009 will be a significant event that will likely shut down most of Highway 75 for several weeks and require the pre-emptive evacuation of dozens of properties that could lose road access to utility services. emergency,” said Manitoba Infrastructure Minister Doyle Piwniuk.
Manitoba could be forced to divert U.S.-bound truck traffic to Highway 3 if North Dakota closes Interstate 29, he said.
As recently as March, Unduche had downgraded the prospect of major flooding this spring. Then came unusual snows in April followed by unusual rains.
Four major precipitation systems passed through the province in April and forecasters are watching for another major system to hit the region this weekend. It is expected to bring another 30 to 80 millimeters of rain to southern Manitoba.
“The probability of getting this rain in April was one in 87 years,” Unduche said.
Piwniuk blamed lows in Colorado for bringing so much moisture to Manitoba.
“If it’s an Alberta mower, there’s not a lot of moisture in that snow, and we’ve had a lot of Alberta mowers through the winter. But when we get Colorado lows , that’s the variable,” he said.
“That’s where we get a lot of humidity and that’s where it kind of joins the Gulf Stream.”
Every community along the Red River has flood protection infrastructure built to deal with the predicted crest in May.
Every town and First Nations community along the Red River in Manitoba is protected by a ring dike built two feet higher than the 1997 flood level.
Every property outside of these communities that ended up damaged in the 1997 flood also had to raise its foundations.
As a result, only a handful of farms and areas that could be cut are at risk of being evacuated, Piwniuk said.
The province is planning for these evacuations by pre-registering people in the flood zone who could be affected, said Johanu Botha, the deputy minister responsible for emergency management.
Sandbag machines have been delivered to communities across the Red River Valley, and infrastructure officials are monitoring overland flooding, he said.
“Overall, our emergency response system has strengthened and we are well positioned to respond to events that may arise,” Botha said.
The City of Winnipeg is also expected to notify other properties of the potential need to construct sandbag dikes.
Unduche said that with the floodway in operation, he does not expect the Rouge River to crest higher in Winnipeg than about 20 feet above normal winter ice level on Ave. James.
On Friday, the Red in Winnipeg stood at 17.3 feet James. The river peaked at 22.6 ft James in 2009 mainly due to ice jams at a time when the floodway could not be operated.
The maximum volume of the Red River at the Winnipeg South Floodway Intake during the 2009 flood was 97,000 cubic feet per second.
Unduche said red is expected to peak south of Winnipeg at peak volume this spring between 94,000 and 121,000 cubic feet per second.
The 1997 Flood of the Century peaked at 138,000 cubic feet per second.
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