Comments | Roseau River First Nation, Sioux Falls, Peguis First Nation, St. Andrews, St. Clements and Selkirk MB, March 24 to May 21, 2009. Overland flooding caused by a combination of snowmelt, seasonal precipitation and the spring breakup affected southern Manitoba's watershed areas of the Red, Pembina, Assiniboine, and Souris Rivers. The event caused flooding of houses and evacuations from communities including Roseau River First Nation, Sioux Falls, Peguis First Nation, St. Andrews, St. Clements and Selkirk. The flooding also resulted in damage to public infrastructure such as bridges, roads, and highways. Three principal factors led to the spring flooding: 1) Heavy autumn rains, about 43 per cent more than normal, saturated the ground just before freezing in early December, which left little room for absorbing snow melt in the spring; 2) It was a snowy winter in southern Manitoba with some 25 per cent more snowfall than normal. Heavy snowfalls and copious spring rains swelled the critical headwaters of North Dakota sending excessive waters north into Canada via the Red River and its tributaries; and, 3) An unseasonably cold spring slowed basin snow melting, ice decaying in rivers, and overland flow from ditches and culverts. |