Uncertainties in models predicting critical bed shear stress of cohesionless particles - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles Journal of Hydraulic Engineering Year : 2022

Uncertainties in models predicting critical bed shear stress of cohesionless particles

Emeline Perret
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Céline Berni
Kamal El Kadi Abderrezzak
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Benjamin Renard

Abstract

Our data show a large scatter for the critical Shields stress for initial sediment motion. The main sources of dispersion are related to the methodological procedures defining the inception of movement (i.e., visual observations or extrapolation of sediment transport rate) and to the estimation of the bed shear stress. The threshold for sediment motion varies with many factors related not only to grain size, but also with bed composition (e.g., presence of fine sediments in a coarse matrix), arrangement (e.g., bed roughness, grain orientation and characteristic lengths 1 Perret, September 2, 2022 of bed structures) and slope. New models to estimate the critical Shields number are proposed combining both grain size or/and bed slope. Model parameters and uncertainty are estimated through Bayesian inference using prior knowledge on those parameters and measured data. Apart from the uncertainty in observations, two types of uncertainty can be evaluated: one related to the parameter estimation (i.e., parametric) and one related to the choice of the model (i.e., structural). Eventually, a four-parameter model based on both the grain size and bed slope yields the best results and demonstrates a potential interaction between these two parameters. Model uncertainty remains, however, large, which indicates that other input parameters may be needed to improve the proposed model.
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Dates and versions

hal-03948254 , version 1 (20-01-2023)

Identifiers

  • HAL Id : hal-03948254 , version 1

Cite

Emeline Perret, Benoit Camenen, Céline Berni, Kamal El Kadi Abderrezzak, Benjamin Renard. Uncertainties in models predicting critical bed shear stress of cohesionless particles. Journal of Hydraulic Engineering, inPress. ⟨hal-03948254⟩
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