Channel-planform evolution in four rivers of Olympic National Park, Washington, USA: the roles of physical drivers and trophic cascades

摘要: Identifying the relative contributions of physical and ecological processes to channel evolution remains a substantial challenge in fluvial geomorphology. We use 74-year aerial photographic record Hoh, Queets, Quinault, Elwha Rivers, Olympic National Park, Washington, USA, investigate whether or trophic-cascade-driven factors – excessive elk impacts after wolves were extirpated century ago are dominant drivers planform these gravel-bed rivers. find that width braiding show strong relationships with recent flood history. All four rivers widened significantly having been relatively narrow 1970s, consistent increased activity since then. Channel also reflects sediment-supply changes, evident from landslide response on River. surmise Hoh River, which shows multi-decadal trend toward greater braiding, is adjusting sediment supply associated rapid glacial retreat. These demonstrate transmission climatic signals through short sediment-routing systems lack buffering by storage. Legacy effects anthropogenic modification likely affect Quinault River planform. We infer no correspondence between abundance, suggesting trophic-cascade this setting subsidiary controls morphology. Our findings differ previous interpretations Park dynamics contrast classic example Yellowstone where legacy overuse apparent morphology; we attribute differences hydrologic regime large-wood availability. Published 2016. This article U.S. Government work public domain USA