Effect of river confinement on depth and spatial extent of bed disturbance affecting salmon redds

Journal of Ecohydraulics
By: , and 

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Abstract

Human impacts on rivers threaten the natural function of riverine ecosystems. This paper assesses how channel confinement affects the scour depth and spatial extent of bed disturbance and discusses the implications of these results for salmon-redd disturbance in gravel-bedded rivers. Two-dimensional hydrodynamic models of relatively confined and unconfined reaches of the Cedar River in Washington State, USA, were constructed with surveyed bathymetry and available airborne lidar data then calibrated and verified with field observations of water-surface elevation and streamflow velocity. Simulations showed greater water depths and velocities in the confined reach and greater areas of low-velocity inundation in the unconfined reach at high flows. Data on previously published scour depth of bed disturbance during high flows were compared to simulated bed shear stress to construct a probabilistic logistic-regression model of bed disturbance, which was applied to spatial patterns of simulated bed shear stress to quantify the extent of likely bed disturbance to the burial depth of sockeye and Chinook salmon redds. The disturbance depth was not observed to differ between confined and unconfined reaches; however, results indicated the spatial extent of disturbance to a given depth in the confined reach was roughly twice as large as in the unconfined reach.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effect of river confinement on depth and spatial extent of bed disturbance affecting salmon redds
Series title Journal of Ecohydraulics
DOI 10.1080/24705357.2018.1457986
Volume 2
Issue 2
Year Published 2018
Language English
Publisher Taylor & Francis
Contributing office(s) Washington Water Science Center, Arizona Water Science Center
Description 14 p.
First page 1
Last page 14
Country United States
State Washington
Other Geospatial Cedar River