Estimating Local Bed Shear Stress in Large Gravel-Bed Rivers

by Peter R. Wilcock, Johns Hopkins Univ, Baltimore, United States,
Alan F. Barta, Johns Hopkins Univ, Baltimore, United States,
Conor C. C. Shea, Johns Hopkins Univ, Baltimore, United States,



Document Type: Proceeding Paper

Part of: Hydraulic Engineering

Abstract: The local bed shear stress τo1 cannot be directly measured and is typically estimated using flow observations in various theoretical or empirical relations. The accuracy of the these methods cannot be directly evaluated, but only judged in terms of physical arguments concerning appropriate conditions for each method and the error associated with the measured quantities. We compare the precision of three common methods appropriate for relatively straight gravel-bed channels with small relative roughness. τo1 estimated from the flow depth and depth-averaged velocity is the most precise because its component quantities can be measured with more precision than the near-bed elevation and velocity required for the other methods.

Subject Headings: Shear stress | Flow measurement | Fluid velocity | Shear flow | Bed materials | Gravels

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