River Crossings and Rockfall
Streams and rivers in and around Sirmilik National Park are mostly glacial fed so the depth and speed change throughout the day, and from day to day. This makes them unpredictable, susceptible to rapid change and challenging to assess for safe crossing.
When the sun is at its strongest, the glacial melt increases and so does the amount of water in the rivers and streams. Rivers and streams tend to be at the lowest levels early in the morning between 2 am and 7 am.
Rainfall affects the river and stream level and flow rate in two ways: by adding more water directly to the flow and by increasing the glacial melt. Increased water levels and flow rate may be immediate or delayed by several hours.
Here are some tips to help you assess rivers and streams and make a safe crossing:
- Cross major rivers and streams early in the day between 2 am and 7 am. This is when the glacial meltwater rate is lowest.
- During and after rainfall watch for deep fast river flow. It may be necessary to wait this out.
- Sections on flat ground with several branches tend to be shallower.
- Use a walking stick or ski pole to test water depth and to help with balance while crossing.
- Link arms to support one another, with the strongest member upstream creating an eddy in their wake for the weaker people downstream.
- Unfasten the waist and chest straps on your pack when crossing, so it can be removed quickly if necessary. People have died because they were pinned down by their pack and unable to escape.
- Neoprene boots with gripping soles will protect your feet from the cold water and tumbling rocks and will keep your boots and socks dry.
- Wait until the water level is lower if in doubt about your ability to ford a stream or river. That could mean a few days!
The dynamic nature of the rivers and streams mean that safe crossing places change. You will have to assess each crossing for yourself, looking up and down stream to find a safe spot.
Bare, freshly broken rock is a sign of active rockfall; these areas may extend well out from the rock walls and cliffs. In or around steep terrain, choose routes carefully, watch and listen for falling rock and avoid stopping for breaks. Be particularly careful when it is raining and during periods of freeze-melt temperatures as these conditions loosen rock and increase rockfall. Choose campsites in protected areas, away from steep terrain.