Four reasons spring flooding occurs in the Prairies
Tuesday, April 8, 2014, 5:39 PM -
An emergency advisory was issued in Alberta this week as concern over spring runoff continues to grow.
It happens every year in this part of the country, due to a combination of factors unique to this portion of Canada.
Here are the four main reasons springtime flooding occurs in the Prairies.
1. SNOWMELT: Generally, the more snow that falls over the winter, the more snow that has to melt in the spring.
"The ... cool spring conditions combined with the heavy snowfalls across the plains during the winter and spring months has resulted in a much above average plains snowpack, that has not had the opportunity to melt gradually," reads a recent provincial spring runoff advisory.
"Typical snow melt in Alberta occurs with gradually warming air temperatures, as opposed to the sudden and sustained increases in temperatures that are expected through this week."
2. TEMPERATURES: A steep warm up isn't the only way temperatures contribute to flooding.
Parts of western Canada saw dangerously cold conditions over the winter. That can freeze the ground, making it difficult to absorb snowmelt and rain.
As temperatures warm up and rain starts to fall, ice jams become a problem.
3. ICE JAMS: Rising temperatures can cause rapid melting, breaking the layer of ice on top of the river.
Chunks of ice then float downstream and can pile up, causing obstructions.
4. GEOGRAPHY Both the Souris and Qu'appelle Rivers meet up with the Assiniboine.
From there, the Assiniboine connects to the Red River in a part of Winnipeg known as “The Forks.”
When the snow begins to melt, all of the water ends up in the same place. To make matters worse, the Red River flows northward. If the Dakotas get hammered with snow, southern Manitoba will eventually have to deal with the melt.
And, to top that off, waters that flow northward are often slowed by ice.