Monday, July 17, 2017

Flood 2017 - Creek Impacts

The July 6 flood certainly had an impact on the creek.  Some sections lost all lose material right down to the bedrock.

Other sections accumulated material brought down from upstream.

Deposition of stone in the creek channel was due to the formation of debris dams that temporarily slowed the speed of the water.  As the water slowed, it lost the energy necessary to carry heavy objects and the gravel dropped out into the creek bed.

Water diverted out of the creek channel carried its sediment load along with it.  A number of sand bars were formed well away from the creek. 

Where the creek left its bed with more momentum, gravel bars were left behind.

There were even a few large flat rocks left stranded far from the creek.

At one bend in the creek the flood water cleaned the face of this bedrock arch.  This feature has never been so easy to view.

Water was deep enough that the meanders in the creek had little effect on the direction of flow.  The current went straight down hill, passing cleanly over every bend and curve in the creek channel.

It was not hard to tell in what direction the water was flowing.  I don’t think a steam roller could have laid these plants down any more than this.  This particular area typically has a nice floral display in late July.  I don’t think that’s going to happen this year.

In the broad, flat areas, water depth peaked at between two and three feet.  It’s going to take a couple of years before the visual effects of this flood event begin to disappear.

4 comments:

  1. Those isolated events often cause more change than all the rest of the days in the year put together, even over several years.

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    1. You're right, Stew. I've seen it many times.

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  2. Wow, that was quite a flood! Great documentation.

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    1. Thanks, Lois. I hope this is the last time we set a new high water record.

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