Saturday, October 11, 2014

Elwha Delta

The Elwha Delta continues to build outward in step with the delivery of sediment from the reservoirs behind the Elwha and Glines Canyon Dams. Both dams are gone, the river is running freely, and an amazing amount of sand has made it to the river mouth, although there is a lot more still to come. 

Gravel is beginning to appear on the new bars and spits at the river mouth, although I suspect it will take repeated cycles of river mouth movement and wave action to recycle and sort this material before more persistent coarse-grained features can form.

For a more thorough update on what's been going on, you might start with Ian's most recent post on the Elwha and then move backwards:
Coast Nerd Gazette: September 2014

One of the most interesting questions, at least to me, is how growth of the delta will eventually contribute to transport of gravel farther down the coast towards Port Angeles. This probably isn't a slow dribbling of material to downdrift beaches, but rather it may be driven by events that release larger plugs of material - a shift in the river mouth, a big storm, the growth of a new spit on the east side - who knows?  I'm glad folks are watching.

Previous posts on Gravel Beach:
Elwha Delta (October 2010)
Elwha Delta (March 2013)
Elwha Delta (July 2013)

There's a lot of great material online about the Elwha and the changes occurring on the coast. Besides The Coast Nerd Gazette, check the National Park Service, and the Coastal Watershed Institute. Lynda Mapes has written Elwha: A River Reborn and there is a documentary film, Return of the River out as well.

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