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Southern Saskatchewan may see flooding this spring

Mar. 12, 2013, Regina, SK - A higher-than-normal snowpack means people in southern Saskatchewan may need to keep rubber boots and, in some cases, sandbags handy this spring.

The Water Security Agency is calling for above normal or well above normal spring runoff in almost all of the southern half of the province -- and it could be worse for some areas. The agency's March forecast calls for very high runoff in areas between Indian Head and Moose Jaw, including Regina, and between Saskatoon and Prince Albert.

There was widespread flooding in southern Saskatchewan in 2011, but the southeast was hardest hit. The causes behind the high flow and flooding in the region that year started in the summer of 2010 with wet conditions on the Prairies. Precipitation was 200 percent above normal immediately upstream of Lake Diefenbaker. More rain that fall led to soil that was at or near saturation at freeze-up, which meant the ground couldn't absorb the subsequent spring runoff. Mountain snowpacks were also higher than average by spring 2011.

John Fahlman, director of hydrology and groundwater services with the Water Security Agency, said there are three factors to consider this year: the fall soil condition, the amount of snow and how fast it melts.

There were relatively dry conditions going into winter, which means the ground can absorb more water. But snowfall is a big issue. A precipitation map shows that a wide area circling Regina and Moose Jaw, and a smaller area around Saskatoon, had 2 1/2 times more snow than normal between Nov. 1 and Mar. 10. The rest of southern Saskatchewan had 1 1/2 times to twice as much snowfall than average.

"Our maps are based on normal precipitation going forward 'til melt," says Fahlman. "Well, if you get some major snowstorms it's going to change. If we get a rapid late melt it means more risk for flooding than a nice, slow gradual melt."

Fahlman said the good news is that areas expecting a very high runoff are smaller than they were two years ago. "The potential for flooding this year is, although it's still high, it's a lot less than it was in 2011," he says.


March 12, 2013  By The Canadian Press


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