Technology Science - Prairie provinces fight rising floodwaters

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Hundreds of people have been forced from their homes across the Prairie provinces as spring floodwaters continue to rise.

The situation in southern Alberta was marginally better on Thursday, as hundreds of homes in the Medicine Hat area, previously thought to be under threat because of a breached dam, were looking somewhat safer.

The latest information suggested rising waters were not as high as feared and there are no plans for evacuations. But officials stressed it's too early to relax, and urged people to keep their eyes on the rivers.

Why is it flooding?

CBC meteorologist Johanna Wagstaffe. (CBC)

CBC meteorologist Johanna Wagstaffe provides some insight on what's causing the flooding across Alberta, Saskatchewan and Manitoba:

"There are a few elements leading to the already busy season and the high peak forecast. Snowmelt is a big one: Parts of Alberta and Saskatchewan were above average for precipitation by almost double between November and early March. But in southern Manitoba, they were actually below seasonal [precipitation levels] from November to March. That would probably affect ice jams more, hence the increase in ice jam flooding in that area. Temperatures are the other factor.

A cold winter has increased run-off with a frozen ground, and the warm spell that the Prairies have experienced over the weekend and early this week caused a lot of fast snowmelt. So the immediate consequence of the combination of precipitation and cold is overland flooding due to frozen ground and ditches in combination with fast snowmelt.

The warm temperatures have also been quickly breaking up ice and causing serious ice jams. The concern over the next couple of weeks will be the actual crest of the rivers, and whether or not the ring dikes and sandbags can hold."

Water levels continue to fluctuate, but cooler temperatures have reduced the flow. Still, a state of emergency for the city remains in place, officials said.

South of Manitoba, the Red River was expected to crest in Grand Forks, N.D., late Thursday, and the crest was downgraded to 15.2 metres, about three metres lower than the major dikes.

"It's well within our ability to control it,'" said Kevin Deans, public information officer in the North Dakota city.

The crest is expected in the Manitoba border town of Emerson between April 22 and 26. In Winnipeg, the time frame is April 27 to May 4.

The upper limit of the Red River in Winnipeg is now expected to be 6.9 metres at the James Avenue pumping station, the city said Wednesday. That's 0.3 metres lower than the March provincial flood outlook and close to the 2009 peak of 6.8 metres.

The number of homes needing sandbag dikes has been reduced to 129 from the 560 noted earlier this month.

Across the province, more than 600 people have been forced out of their homes by swollen creeks and rivers and flooding. Eleven municipalities have declared states of emergency and many municipal roads have been closed, including 55 highways.

Or the Peguis First Nation north of Winnipeg, roughly 300 people left Wednesday to stay ahead of the deluge. But many of the homeowners left not because their homes were in immediate danger, but because flooding nearby was cutting off road access.

Patients at a health centre in Gladstone were moved to another facility due to flood fears. Eight patients, mostly seniors, were transported by ambulance. A sandbag dike was created to protect the town from the nearby Whitemud River, which rose by one metre Tuesday.

In Wawanesa, 21 clients of a personal-care home were similarly moved to another facility as a precaution. The homes themselves may not be lost, though.

Trans-Canada Highway flooded

In neighbouring Saskatchewan, some 230 people were told to leave the Cowessess reserve east of Regina.

A large section of the Trans-Canada Highway east of Regina was covered with water Wednesday, but some traffic was still moving through.

Meanwhile, 12 new communities were approved to receive funding under the province's emergency flood damage reduction program on Thursday. Burstall, Eastend, Frontier, Mendham and other communities in the province's southwest will share $127,000 from the Saskatchewan Watershed Authority for flood prevention.

There are flood concerns in parts of British Columbia, too, as officials in Smithers, B.C., are warning of a potential ice jam on the Bulkley River.

The last time it did so was two years ago, when the Ebenezer Flats and Dohler Flats areas were affected. Local officials are making sand and sandbag supplies available as a precaution.