Mt. Nusatsum

Mt. Nusatsum

Thursday, January 6, 2011

Log Jams

During the Great Flood of 2010 in the Bella Coola River, Atnarko River and the tributary streams, huge amounts of logs other wise known as Large Woody Debris (LWD) were added to the river system from adjacent banks and the old LWD moved around.  During the peak of the flood while it was daylight and we could watch the river, the amount and size of trees floating pass was quite astounding. While the water was high a lot of the trees moved right through the river system and ended up in the ocean at North Bentinck Arm.  The inlet was seriously plugged with debris for a number of days while it dissipated.  It even affected getting the ferry in to move people because of the hazard caused to navigation.

Trees that end up in the ocean spend the rest of the their lives becoming worn and smoothed as beach drift wood.  Some of the better logs are captured by log salvage and sold for use as lumber, but travel anywhere on our coast on virtually any beach you will see large amounts of logs at the high tide line.  If you have ever wondered where all this wood comes from, it's not all escaped from logging operations, but a huge amount originates every year from our large coastal rivers and during the big coastal rains which cause natural landslides, many of which go straight into the ocean on the steep coastal fjords.

I have heard from some people that some of the big log jams in the Bella Coola River that have been largely in place for 30 years or more (that's why LWD is valuable for fish habitat, it helps stabilize stream channels) have all been moved and the path is pretty clear.  The next few 'moderate' floods will be pretty interesting as a lot of the wood will move around in system to find its new stable location.   Grizzly

No comments:

Post a Comment