You are here: Home
/ Publication Information
Title: Bed stability in unconfined gravel bed mountain streams: With implications for salmon spawning viability in future climates
Author: McKean, Jim; Tonina, Daniele
Source: Journal of Geophysical Research: Earth Surface. 118: 1227-1240.
Publication Series: Scientific Journal (JRNL)
Description: Incubating eggs of autumn-spawning Chinook salmon (Oncorhynchus tshawytscha) could be at risk of midwinter high flows and substrate scour in a changing climate. A high-spatial-resolution multidimensional hydrodynamics model was used to assess the degree of scour risk in low-gradient unconfined gravel bed channels that are the favored environment for autumn-spawning salmon in mountain watersheds such as the Middle Fork Salmon River (MFSR), Idaho. In one of the most important MFSR spawning tributaries, near-bed shear stresses were relatively low at all discharges from base flows to 300% of bankfull. The highest stresses were found only in small areas of the central flow core and not at spawning sites. Median shear stresses did not increase in overbank flow conditions because poor channel confinement released the excess water into adjacent floodplains. Channel and floodplain topography, rather than discharge, control the maximum near-bed shear stresses. Over the modeled range of discharges, ~2% of the total surface area of the main stem channel bed was predicted to be mobile. Even in known spawning areas, where shear stresses are higher, <20% of the spawning surface area was mobile during overbank flows with a 2 year recurrence interval. Field measurements of little gravel transport during flows that were 93% of bankfull support the numerical model predictions. Regardless of some uncertainty in future climates in these watersheds, there appears to be relatively limited risk of extensive scour at salmon spawning sites in any likely hydrologic regimes.
Keywords: Chinook salmon, Oncorhynchus tshawytscha, gravel bed mountain streams, spawning
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
XML: View XML
McKean, Jim; Tonina, Daniele. 2013. Bed stability in unconfined gravel bed mountain streams: With implications for salmon spawning viability in future climates. Journal of Geophysical Research: Earth Surface. 118: 1227-1240.
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility