How River Breakup Happens
Observation reports and maps from the Alberta ministry of Environment and Parks offer snapshots of ice conditions on the Athabasca River upstream and downstream from Fort McMurray.
Live River Camera
Watch the ice from a safe distance through the River Breakup Camera.
You might be surprised to learn that the majority — about 60 per cent — of all rivers and waterways in Canada flow from the south to the north.
The Athabasca River adjacent to the Lower Town Site of Fort McMurray is one of these north draining rivers. Its waters join with others and ultimately empty into the the Arctic Ocean.
When southern snowmelt enters the Athabasca River, it eventually flows into ice formations further north that have not yet weakened.
Some years, as these flows head downstream (north), the solid ice is lifted by rising water levels breaking it into chunks. These chunks are then pushed downstream. This type of breakup is known as a dynamic breakup.
Other years, the warmer snowmelt thaws the ice and a thermal breakup occurs. Picture an ice cube slowly disappearing in a glass of water as it melts.
Thermal and Dynamic Breakups
The type of breakup (thermal or dynamic) is dependent on weather and river conditions.
Thermal processes melt the ice cover and weaken it. Contributing factors include: sunshine or wind, increased water or air temperature.
Dynamic processes push the ice cover out of its original place. Contributing factors include: increased precipitation, increased water levels, water movement that causes the ice cover to break before it has weakened.
Dynamic processes are usually associated with higher flood risk, as they are more likely to cause an ice jam.
This is especially true in the Fort McMurray area where a sudden release of an ice jam upstream can result in a surge of ice and water which can lead to flooding.
Thermal river breakup
Dynamic river breakup