ENVIRONMENT YUKON






 

Lakes and Rivers

Yukon River ice break-up at Dawson City

 

Significance

 

The timing of river ice break-up is one factor influencing the potential for break-up severity and associated negative impacts. In general, earlier break-ups result in a compressed runoff period, increasing the potential for severe ice jams that lead to floods.

River ice conditions also affect transportation routes, both for winter roads and wildlife corridors. Earlier river ice break-up and increased severity of ice-jamming can have detrimental impacts on communities and infrastructure.

Earlier river break-up over the past century is a strong indicator of a changing climate. Warmer spring and winter temperatures contribute to reduced thickness in river ice and earlier break-ups.

 

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What is happening?

Ice break-up on the Yukon River at Dawson City now occurs more than seven days earlier on average than in 1896, when data collection began (Figure 1).

Eight of the ten earliest recorded break-up events at Dawson City have occurred in the past 30 years.

 

Yukon River. © Richard Legner 2013.
Figure 1: Date of ice break-up on the Yukon River at Dawson City, 1896-2016.

 

Taking action

 

Two research projects are underway in collaboration with the Emergency Measures Organization to help Yukon communities prepare for flooding events:

  • Yukon flood risk mapping: using high resolution LiDAR elevation data to identify flood prone areas near Yukon communities.
  • Development of flood hazard perception stages: categorizing water level stages into severity indices ("Action Stage", "Minor Flooding", "Moderate Flooding" and "Major Flooding") that determine when and what action should be taken against an impending flood.

 

2013 saw the most floods in Yukon in 30 years.

 

 

Data quality

  • Yukon River ice break-up at Dawson City statistics and photo documentary are available at: http://www.yukonriverbreakup.com/statistics
  • At first a betting tradition, the exact time and date of break-up has been recorded at Dawson since 1896.
  • A tripod has been set up on the ice and connected by cable to the Danoja Zho Cultural Centre. When the ice starts moving, it takes the tripod with it and stops the clock, thereby recording the official break-up time.

 

Further information

Visit www.yukonwater.ca to find information about Yukon's water resources and how our water is used, managed and monitored.

A Government of Yukon Water Resources Branch presentation about climate change and water.

Profile

Record breaking break-up

 

Spring 2016 earliest river break-up on record for the Yukon River at Dawson.

 

In 121 (1896 to 2016) years of recorded river break-up dates in Dawson City, the Yukon River has never given way as early as in 2016. Not only did the April 23 break-up set a new record, it smashed the record by four days, and required organizers of the annual river break-up contest in Dawson City to adjust the cut-off date for predictions. The break-up occurred two weeks earlier than average, although this shift is normal, as the average break-up date over the past 30 years has been occurring earlier.


Two primary factors contributed to the record setting river break-up date: air temperatures were well above normal for the first two weeks of April, and the winter was extremely mild. In fact, winter air temperatures in Dawson City were also record breaking and 2016 was the warmest winter on record dating back to 1902.


The mild winter led to a thin ice cover that began melting with the early arrival of above zero temperatures. The conditions caused a “thermal” break-up event, meaning there was significant melting prior to ice movement which lowered the risk of flooding. The 2016 Yukon River break-up had no major ice jams and water levels at Dawson City remained well below flood stage levels.