Due to heavy rains in southern Alberta, many rivers are high and over 100,000 people have been ordered to evacuate. The bulk of the news coverage is around Canmore and Calgary, but all of southern Alberta, particularly the southwestern part, is affected. Here are some photos from the Nanton News:
This is a photo of flooding near Nanton, courtesy of Nanton News.
Chain Lakes flooding
southern Alberta flooding – Highway 22
Advisories
Here are some links to the official advisories:
River basins under advisory (Global News)
Environment Canada weather advisories
Return Period
My preliminary estimate is that in the upper Bow River, Canmore to Calgary corridor, this flood is in the range of 1:75 – 1:100 years.
South of Canmore, in the eastern slopes down to the Crowsnest Pass and Waterton Park, as well as east toward Lethbridge, this is likely in the 1:50 range.
Past Major Floods
In the recent past, the major floods in southern Alberta have been 2010, 2005 and 1995, the latter being the largest. It is generally considered a 1:100 year event. Although the crest of the Oldman River in Lethbridge is expected to be this afternoon at a similar level, I don’t believe this flood is bigger than 1995 yet. However, from Calgary to the west, it probably is. None of those three recent events resulted in downtown Calgary streets underwater.
Roseke Engineering is available to view flood damaged sites and provide assessments, as well as long or short term recommendations. Please call Bernie at (403) 393-6170.
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