Research Article| January 01, 2005 Field measurements of incision rates following bedrock exposure: Implications for process controls on the long profiles valleys cut by rivers and debris flows Jonathan D. Stock; Stock 1Department Earth Planetary Science, University California, Berkeley, California 94720, USA Search other works this author on: GSW Google Scholar David R. Montgomery; Montgomery 2Department Space Sciences, Washington, Seattle, Washington 98195, Brian Collins; Collins William...

We examined changes in wood abundance and functions Puget Lowland rivers from the last ~150 years of land use by comparing field data an 11-km-long protected reach Nisqually River with Snohomish Stillaguamish archival several rivers. Current is one to two orders magnitude less than before European settlement basins. Most importantly, jams are now rare because a lack very large that can function as key pieces low rates recruitment. These size appear have fundamentally changed morphology,...

Research Article| July 01, 1986 Erosion of tephra from the 1980 eruption Mount St. Helens BRIAN D. COLLINS; COLLINS 1Department Geological Sciences and Quaternary Center, University Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar THOMAS DUNNE Author Article Information Publisher: Society America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print 0016-7606 GSA Bulletin (1986) 97 (7): 896–905....

Abstract Changes in the severity and likelihood of flooding events are typically associated with changes intensity frequency streamflows, but temporal adjustments a river's conveyance capacity can also contribute to shifts flood hazard. To assess relative importance channel hazard, we compare variations flow magnitude moderate (1.2 years) floods at 50 river gauges western Washington State between 1930 2020. In unregulated rivers, have increased across region, regulated rivers this trend is...

Abstract Historically in Puget Lowland rivers, wood jams were integral to maintaining an anastomosing channel pattern and a dynamic channel–floodplain connection; they also created deep pools. In the late 1800s, was removed from most rivers isolated their floodplains, riparian forests cut down, limiting recruitment. An exception this history is 11‐km‐long reach of Nisqually River, which has natural banks mature floodplain forest. We use field archival data River explore questions relevant...

Abstract River channel beds aggrade and incise through time in response to temporal variation the upstream supply of water sediment. However, we lack a thorough understanding which these is dominant driver bed elevation change. This hampers flood hazard prediction, as changes can either augment or reduce heights. Here, explore drivers change using multidecadal series river at 49 United States Geological Survey (USGS) gage sites uplands Washington State, USA. We find that elevations many...

Research Article| May 01, 2016 Rates and mechanisms of bedrock incision strath terrace formation in a forested catchment, Cascade Range, Washington Brian D. Collins; Collins † 1Department Earth Space Sciences Quaternary Center, University Washington, Seattle, 98195-1310, USA †bcollins@uw.edu Search for other works by this author on: GSW Google Scholar David R. Montgomery; Montgomery Sarah A. Schanz; Schanz Isaac J. Larsen 2Department Geosciences, Massachusetts, Amherst, Massachusetts...

Abstract Mass movements from glacial and lahar terraces in the middle lower reaches of rivers draining Washington Cascade Range to Puget Sound may represent a substantial but poorly quantified portion those rivers' sediment supply pose significant mass movement hazards. We used repeat LiDAR elevation data, aerial imagery, well logs quantify characterize terrace delivery nine major watersheds over median period 12 years. In 1,946 river kilometers for which was available (71% 2,736 total...

Significance The degree to which bedrock-floored rivers are shaped by human action is poorly understood in comparison with gravel- and sand-bedded rivers. Yet, bedrock river erosion thought set the pace of landscape-scale evolution, thus any human-induced has potential have a cascading effect alter both networks hillslopes. We show here that artificial dam-burst floods wood removal early 20th century associated forestry practices caused significant incision led abandonment predisturbance...

Abstract Repeated measurement of tephra erosion near Mount St. Helens over a 30‐year period at steel stakes, installed on 10 hillslopes in the months following 1980 eruption, provides unique long‐term record changing processes, controls and rates erosion. Intensive monitoring first three post‐eruption years showed declined rapidly as processes shifted from sheetwash rilling to rainsplash. To test predictions about changes made based 3‐year record, we remeasured sites 1992, 2000 2010. Average...

Abstract The 1980 eruption of Mount St. Helens covered soils with a tephra blanket and killed the forest tree cover in 550 km 2 area. After eruption, rates sheetwash rill erosion, plant were measured on tephra‐covered hillslopes which had been subject to three land‐management practices: grass seeding; scarification, salvage logging. On rapidly‐eroding seeding, limited covers established only after erosion declined sharply. Logging trees downed by scarification previously logged surfaces...

Sauer et al. (2004) advocate the use of trend estimation models that adjust counts for differences among observers. We agree such adjustments are sometimes needed, and we noted (Bart 2003) they may readily be carried out prior to using method described. Including observer covariates, however, is not always necessary substantially reduces precision, as acknowledge. Furthermore, under plausible conditions, including covariables introduces bias rather than removing it. In addition, weighting...