Rainforest Rivers of the Outer Olympic Coast


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This imagery shows floodplain details from five rivers on the outer Olympic Peninsula—the Quinault, Queets, Hoh, Bogachiel/Quillayute, and Sol Duc. The headwaters of these rivers begin in melting snowfields and glaciers of the Olympic Mountains. They then flow through a region of dense temperate rainforest and westward to the Pacific Ocean.

The brightest white areas represent the river elevation (set to 0 feet), and as elevations increase in the floodplains, the white progressively changes from light green to dark green. This type of model shows where river channels have migrated in the past by vividly displaying floodplain features such as terraces, meander scars, and oxbow lakes.

Channel migration can be affected by a number of factors including topography, geology, land use, and land cover, such as forest. Large woody debris from the western Olympic Peninsula’s mature rainforest stabilizes floodplains and reduces channel migration by restricting flow and keeping sediment in place. Historic removal of large trees from riparian zones in the lower reaches of these rivers has increased sediment transport and channel movement.

This poster was made by DGER cartographer Dan Coe and is available here for download.

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