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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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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of the community of Aklavik. The community of Aklavik remains today, with the community slogan of “Never Say Die.” Rivers were not the only source of flooding in the far north, with the Arctic Ocean periodically flooding the community of Tuktoyaktuk with storm surges that have eroded away considerable portions of the community waterfront. Tuktoyaktuk has invested millions of capital dollars in shoreline erosion protection that required the hauling of large rock by ice road from Inuvik, which is 140 km. to the south. Flooding is also prevalent in Nunavut Territory, where the community of Kimmirut on south Baffin Island experienced rain and warm weather in May 2012, which caused a flash flood and damaged a public housing duplex. The cause of the flow was a torrent of slush and snow that rushed down a hill near the airport at 2 in the afternoon. In March 2013, a flooding concern was raised about huge piles of snow in the community, as a result of increased snowfall during the winter, which led to a build-up on roadsides and on top of local lakes. The hamlet took precautions to avoid a repeat flooding situation by excavating some strategically located
ditches, and clearing snow away from the duplex that was flooded in 2012. The Nunavut community of Rankin Inlet on Hudson Bay experienced a potential flooding disaster in 2013, when the accumulated snowfall during a blizzard from May 14-16 broke records for the area. Environment Canada reported that close to a year’s worth of snow fell over those three days, amounting to about 92 cm. Fortunately, the snow melted slowly enough that flooding was not an issue. The community of Kugluktuk on the arctic coast of Nunavut has developed a rudimentary surface water management system to collect surface water and convey it to the ocean through a series of ditches and culverts. However, Kugluktuk suffers from the broad range of challenges associated with the operation and maintenance of a drainage system, such as damage to culvert ends and blockages in the ditch systems. In spite of a having a drainage system, catastrophes can occur and cause significant damage, such as the Kugluktuk rainfall event in 2007 that washed out significant sections of the community roads.
A very uniquely northern element associated with drainage is permafrost, which is problematic when water and permafrost interact. Permafrost is very erosion sensitive due to the inherent ice content. When water and ice meet, the water wins and the ice is quickly melted. This sensitivity of permafrost is evident in the instability of embankments along the main drainage course in the community of Kugluktuk. The land of ice and snow is a land of water and runoff for a portion of each year, and with this comes potential flooding. The prevalence and magnitude of this flooding are in a state of transition, as climate change in the arctic appears to be throwing out what was ‘normal’ and introducing a permanent state of flux.
Tuktoyaktuk shoreline erosion protection
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