PACTS on WATER & WASTEWATER M I : g F l oo d i n
Cryofront: News, Views, and Muse from the Far North KEN JOHNSON, STANTEC Flooding in the Far North n this huge region of Canada, which is perceived by many as a land of perpetual ice and snow, the idea of flooding and its potential impacts may be dismissed as infrequent and inconsequential. This could not be further from the truth. The scale of flooding in the north does not come anywhere near the scale of flooding in the south, particularly as it was demonstrated with the southern Alberta flooding in 2013. However, scale does not diminish the ultimate impact of the flooding on a northern community. The most famous of northern towns, Dawson City flooded 22 times in the period of 1898 to 1979; in 1979 a heavy snowfall and spring ice breakup on three rivers caused the Yukon River to pour into this historic gold rush town. As reported in the media, “The water burst through the makeshift bank at midnight, but fortunately most people were awake and alert so there were no lives lost.” Most of Dawson City floods were minor, others were serious, and floods in 1925,
1944, 1969, and 1966 caused considerable damage. The flood of 1979 prompted the construction of a perimeter dyke around the entire river-side edge of the community at a cost of $3 million to protect against a 1-in-200-year flood associated with ice damming. The phenomenon causing the flooding in Dawson City is a function of the adjacent confluence of the Klondike River and the Yukon Rivers. The smaller and cleaner Klondike River ‘breakup’ is generally sooner than the Yukon River, which sends chunks of ice into the Yukon River. These chunks will dam up in the narrow ice covered section of river adjacent to Dawson City creating an ‘ice dam’ that can cause the river to rise several metres in a matter of hours. A unique attribute of breakup in Dawson City is the ‘ice lottery,’ which has a cash prize going to the person with the closest guess for the exact time that the ice in front of the community starts to move. The ‘ice lottery’ has been an annual event since the spring of 1897.
Kugluktuk rainfall flooding erosion
Confluence of Klondike and Yukon Rivers at Dawson City; the Klondike River is the clear water
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48 | Western Canada Water | Spring 2014
Another northern centre, the Town of Hay River experienced such regular flooding from ice damming on the Hay River, that a local resident, Red McBryan, developed a 50-year hobby of river watching during each spring breakup. Hay River’s flooding prompted a relocation of the community centre to higher ground in 1963. The ice jamming is the result of river ice breakup in the Hay River flowing into the still frozen Great Slave Lake causing the formation of a dam of ice, which backs up the flow and water levels in the river. The most infamous of the flood prone northern communities is Aklavik, which was the historical regional centre of the Mackenzie Delta. Although the community does not suffer from ice dam flooding, its low elevation in the middle of the Mackenze Delta allows at least a portion of the community to flood on a regular basis. The chronic flooding problem prompted the creation of the Town of Inuvik in the early 1960s, and the complete relocation, in principle,
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