Ice Jam Formation and Release Dynamics - Hay River, NWT

每年春天，河流破裂给加拿大许多位于河流周围的社区带来了冰堵塞洪水的威胁。当融雪使溪流膨胀，突然抬升并打破冰盖时，就会发生崩解性冰塞。冰块最初可能会随着融雪流一起被带走，但通常会变得拥挤——可能在桥上，在河流的一个狭窄的弯道上，或者在岛屿之间——当这种情况发生时，冰塞就形成了。水流被这个冰坝阻挡，水位可以以每分钟60到90厘米（2到3英尺）的速度上升，几乎没有任何预警。位于西北地区大奴隶湖南岸的海伊河镇就是这样一个社区；每年春天那里都会形成冰塞。近几十年来最严重的洪水发生在1963年。当地居民罗伊·法比安（Kátl 'odeeche First Nation的前酋长）在洪水发生时还是个孩子，他向我们讲述了一个可怕的故事，他从他家二楼的窗户被船救了出来。他们疯狂地向灌木丛划去，当他回头看时，他看到一堵水墙从水道里涌了出来。他说，他看不到对岸30英尺高的树，因为一旦结冰，冰就堆积得这么高。最近，2003年和2008年发生了严重的洪水，2005年、2007年和2009年发生了轻微的洪水。每年春天，加拿大各地的许多社区都受到冰塞的威胁，为了确保人们和财产的安全，需要实用可靠的河流冰塞洪水预报工具。为了建立这样的模型，我们需要研究冰塞的行为，既要了解它的复杂性，又要有必要的数据来测试我们的模型。由于有发生冰塞的倾向，并且需要洪水预警系统，海溪河是进行此类科学研究的理想地点。这个网站的研究也为我们提供了每年春天直接帮助社区进行洪水预报的机会。

Each year during the spring, river breakup brings the threat of ice jam floods to many of the communities across Canada that are situated around rivers. Breakup ice jams occur when snowmelt swells the stream, and lifts and breaks the ice cover suddenly. The ice pieces may initially be carried along with the snowmelt flow, but often become congested - perhaps at a bridge, at a tight bend in the river, or in amongst islands - and when this happens an ice jam is formed. The streamflow is blocked by this dam of ice, and water levels can rise at rates approaching 60 to 90 centimeters (2 to 3 feet) per minute, with virtually no advance warning. The Town of Hay River, situated on the south shore of Great Slave Lake in the Northwest Territories is one such community; ice jams form there every spring. The most extreme flood in recent decades occurred in 1963. Local resident Roy Fabian (former Chief of the Kátl`odeeche First Nation) was a boy at the time of the flood and recounted for us a terrifying story of being rescued by boat, from the second story window of his house. They paddled furiously towards the bush, and as he looked back, he saw a wall of water surging from the channel. He said he could not see 30 foot high trees on the opposite river bank the ice had piled so high once the jam formed. More recently, severe flooding occurred in 2003 and 2008, and minor flooding in 2005, 2007 and 2009. To ensure the safety and security of people and property in the many communities across Canada that are threatened by ice jams each spring, practical and reliable river ice jam flood forecasting tools are needed. To develop such models we need to study ice jam behaviour, both to understand its complexities, and to have the needed data to test our models. With its propensity for ice jam occurrence, and its need for flood warning systems, Hay River represents an ideal location for such scientific studies. Research at this site also affords us the opportunity to directly help the community in their flood forecasting efforts each spring.