Hay River Breakup 2009
last updated May 14, 2009
Coming soon: more photos, some satellite images of the ice jam
Breakup Wrap-up:
See some pictures of the flooding that occurred on Vale Island and on the KFN road to the Old Village.
Just how high
did the water get this year, compared to 2008, and earlier events?
Actually - as you can see from the profiles below, the 2009 flood levels (red line) were very close to the 2008 flood levels (blue line). In many places they were essentially the same; downstream of NTCL in the docks area, 2009 levels were less than 30 cm (about one foot) lower than the 2008 levels. (Also shown are the 1963 and 1985 profiles - the two largest documented events.)
What is different this year, compared to 2008, and why wasn't the flooding worse?
We think there are two main reasons:
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Cold weather just prior to breakup delayed snowmelt runoff coming from the upper part of the Hay River basin. In 2008 the peak flow at breakup was about 900 cms, in 2009 the river's flow during breakup was only about 500 cms. In fact, you may have noticed that the flow in the river was still increasing after breakup this year (it was up to about 880 cms by May 9). We expected the peak flow to be higher in 2009 than in 2008, and it was, but thankfully that peak flow occurred well after the 2009 breakup was over. If that higher flow had occurred during breakup - the flooding would likely have been very severe.
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In 2008 there were actually two ice jams in the East Channel - one out at the lake and another by NTCL. The lake ice was intact and flow could not escape easily, so the water backed up and flooded land on both sides of the East Channel severely. In 2009, the toe of the ice jam pushed all the way to the lake on May 6, but there was an opening in the lake ice cover right at the jam toe location (see the photo below). This allowed some water to escape, and so less backup occurred. As a result, by the morning of May 7, 2009 water levels were already dropping upstream of the ice jam.
What did we learn from breakup 2009? What do we still need to discover?
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A key aspect of breakup at the town of Hay River is the arrival of waves of ice and water from releasing upstream ice jams. Usually the water wave arrives ahead of the ice run. For this event, we were able to correctly predict the time of arrival of the water wave at the Pine Point Bridge as 5:00 AM on the morning of May 6. However, the timing of the arrival of the ice itself was about an hour later than our model predicted. This is likely due to the ice slowing down in the tight river bends between Enterprise and the Pine Point Bridge. This is an effect that our ice forecasting model can only account for approximately. This 2009 data will be extremely useful in helping us to improve our ice jam release forecasting models to better account for this effect.
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The toe of the East Channel jam had not pushed all the way to the end of the East Channel since 1963 and that event resulted in the worst flood in the past 45 years (likely longer). So 2009 is the first time such an event has ever been scientifically documented. In fact, 2009 is also the most comprehensively documented breakup at Hay River ever. In total 13 ice scientists from the UofA and DIAND were here documenting and measuring every aspect of breakup in partnership with the Town EOC - and we will be analyzing this data for the next year at least. We hope to learn from this what combinations of ice forces and stream flow are required to cause ice jams to push all the way to the lake in the East Channel, and what water levels to expect when this happens.
What will we be doing next?
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As you can imagine - the complex interactions of ice and water in multi-channel rivers is still in its infancy - this research at Hay River will not only help us understand the Hay River's behaviour better - it will help us to develop and improve our computer models of such occurrences to benefit other communities that are similarly threatened. This year, we forecasted that flooding would likely occur along the East Channel in Hay River. But in future, we actually hope to be able to predict the severity of flooding that might be expected (that is, the actual flood extent expected.) This is the most challenging aspect of our research.
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We will be back in Hay River next year to monitor breakup yet again. We will be flying the river daily and producing maps of ice conditions, and we will be advising EMO of our observations and expectations. We are committed to providing the community with detailed information on breakup events as rapidly as possible. However, we have been finding that this is difficult to do, since we are a small team of people and we get more and more busy as breakup progresses. As a result, we tend to publish less and less information just as you need much more detail. To improve on this service, in 2010, we will be working in collaboration with the Town EMO to provide our information to you directly through their web site. Working together, we will be able to provide much more information to you, especially when it is most needed.
Known conditions as of 7:00 AM on May 7:
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All of the ice from the NWT/AB border has now come down. There was a large ice jam on the river at Grumbler Rapids, which released late in the evening of May 5. This wave of ice and water pushed out the gorge jam bringing that ice along with it to the town of Hay River.
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The ice jammed in the West Channel, pushing down through the Rudd and Fishing Village channels and across the island. (photos will be posted shortly). The ice pushed right down the East Channel through to Great Slave Lake. Flooding occurred along the East side of Vale Island, and came over part of the road to the Old Village on the KFN reserve. The upstream end of the ice jam is downstream of the Pine Point bridge.
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We have had no opportunity to fly the river since the ice pushed down to Great Slave Lake in the East Channel late yesterday afternoon and so cannot say if the ice will push higher in the East Channel. However, water appears to be escaping through at the centre of the channel at the lake end of the East Channel, river levels are steady locally, and the discharge is decreasing for now at least. The forecast is for sunny weather which will warm the river water upstream and should melt out the jam relatively quickly.
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Photos will be posted shortly. This is our the last report.
Known conditions as of 5:00 AM on May 6:
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the water wave has arrived in Hay River - expect pushing ice in both channels
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ice wave will likely appear within the hour
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no more reports will be issued until later today
Known conditions as of 4:00 AM on May 6:
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The ice jams at Enterprise released at approximately 2 AM - ice was running bank to bank at high speed for approximately 80 minutes.
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The water level started rising at Paradise Gardens at approximately 3 AM. Ice is now running bank to bank there and water levels are up 7 ft.
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estimated soonest arrival at the Pine Point Bridge is 5:00 AM
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further updates will be posted on this site hourly (on the hour) - no further emails will be issued tonight
Known conditions as of 7 PM on May 5:
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There has been no significant change in conditions since this afternoon's update.
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Water continues to build behind the ice jams in the gorge. See a photo taken of Louise Falls tonight, showing this backwater.
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Here is the flight map showing ice conditions as of noon today (described below). There is not a lot of ice left in the river between the falls and the border (as the flight map shows), but there is still some ice to come down.
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We believe that there are two possible scenarios for the release of this jam: an incoming ice run (and accompanying water wave) from upstream could destabilize it; or, the water could build up so much that the ice jam could simply not withstand the forces. Either way, a release of this ice jam would likely bring a great amount of ice and water into town, so it presents a flood risk.
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The Town's EMO is watching the river at Enterprise and will warn everyone if the gorge jam releases.
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more info will be posted here as time permits ...
Recent developments, known as of 2:00PM on May 5:
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There are still two small ice jams at Enterprise, and one large ice jam in the Gorge.
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There is light ice running in to the head of the jam in town.
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There is localized sheet ice up river near the border - which is possibly now moving down to the falls.
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A flight map will be posted shortly.
Recent developments, known as of 7:00 AM on May 5:
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Incoming ice was been pushing down both the East and West Channels overnight. The ice has packed in very tight and high in the East Channel particularly, and the toe is below the usual spot at Island D. It is now at the end of Island B (Nelson Island). Our profile team is out measuring the jam right now.
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There are two small ice jams at Enterprise, and one large ice jam in the Gorge. All were still in place as of 9:30 pm Monday evening.
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more info will be posted here as time permits ...
Recent developments, known as of 1:00 AM on May 5:
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The ice has been pushing down both the East and West Channels over the day.
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There are two small ice jams at Enterprise, and one large ice jam in the Gorge. All were still in place as of 9:30 pm Monday evening.
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During Monday afternoon and evening the ice sheet ice was breaking out between Enterprise and Paradise Gardens, causing several ice runs. Some of this ice jammed briefly upstream of Paradise Gardens (around 2:00 to 2:30 pm), then released and ran past the Paradise Gardens gauge at ~5:20 pm. This ice jammed again just downstream of Paradise Gardens and then released at about 8:40 pm. Two other smaller ice runs have passed Paradise Gardens since that time.
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The first wave of ice and water progressed downstream to town, with the front of the water wave eventually moving ahead of the ice. By the time that running ice was reported at the Golf Course at ~10 pm, the front of the water wave had reached the Pine Point Bridge.
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The water wave moved into the delta, pushing the toe of the jam down past the NTCL berm. The ice in the East Channel is reported to be at the top of the dock at Fisherman's Wharf, and possibly over the NTCL berm, as well. Water levels were down in the West Channel. Ice is still running into the delta at this time, most into the East Channel.
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There are two (smaller) waves of ice and water coming down from Paradise Gardens.
What you'll find on this site ...
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Photos taken during our daily observation flights (April 29th Alex. Falls photo posted)
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Our breakup reports, including maps and photos showing ice conditions in the river upstream of the town of Hay River. These will be updated when time permits.
Sign-up for E-Mail UpdatesYou can now sign-up to receive our breakup reports (~ 1 per day) by e-mail. Click here to subscribe. |
Webcams (click on an image to enlarge) |
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Note*: Communications with these remote stations may sometimes delay the most recent image being posted here. Check the archive (link below each photo) for a list of all the photos received from a webcam. |
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Hay River near Meander River |
Hay River at Alexandra Falls |
Hay River at Paradise Gardens |
Hay River at Pine Point Bridge |
You can see more data on the Town of Hay River EMO web site
Winter survey 2009 - Hay River ice thickness was measured in mid-March both manually and by using Ground Penetrating Radar. See a map showing some of the data or see some photos of the pressure ridge on Great Slave Lake.
What leads to a big flood at Hay River? It seems to be strongly related to the peak flow in the river during the snowmelt period. See a graph of past flood peaks and flood severity.
What's expected in 2009? The peak flow at breakup depends upon many things, including the snow pack in the basin and the weather during breakup. See a graph comparing 2009 snowpack to earlier years.
Want to lean more about this research project? Click here...
Have a Hay River flood story? Want to comment on this page? We'd love to hear from you. Please email Faye Hicks.
This research is funded by the Natural Sciences and Engineering Research Council of Canada (NSERC). We gratefully acknowledge that support!
Thanks also to our project partners: the Department of Indian Affairs and Northern Development (DIAND) and the Town of Hay River!