Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Heyman, Joris; Bohorquez, Patricio; Ancey, Christophe

doi:10.1002/2015jf003672

Cited by 49 publications

(80 citation statements)

References 111 publications

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“…Therefore, the global proportion of motion was estimated by pooling all the observed particles. Using this approach, one envisions each particle observation as a random outcome of the same process, as discussed by Heyman et al (). Therefore, the global proportion of motion was estimated using a new version of equation that jointly considered the contributions of all the observed particles to a global T m and a global T :

ϑ^{m} ≅ \frac{\sum_{i = 1}^{N} T_{A}^{m} ((), i)}{\sum_{i = 1}^{N} T_{A} ((), i)}

…”

Section: Application To Experimental Resultsmentioning

confidence: 99%

“…When the area A is not sufficiently large to consider N A as constant, a correlation term must be added to equation . As discussed in Ballio et al (), if one considers an instantaneous solid discharge equal to the product of instantaneous concentration and velocity ( Q / B = Cu ), then the time‐averaged solid discharge is

\frac{\overset{true¯}{Q}}{B} = \overset{C}{true} \overset{u}{true} + \overset{C' u'}{true},

where the correlation term can be interpreted as a diffusive flux (e.g., Ancey & Heyman, ; Furbish, Roseberry, et al, ; Heyman et al, ). The relative weight of the mean and fluctuating terms in equation may also depend on the choice of the variables.…”

Section: Proportion Of Motionmentioning

confidence: 99%

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Lagrangian and Eulerian Description of Bed Load Transport

et al. 2018

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Sediment particles transported as bed load undergo alternating periods of motion and rest, particularly at weak flow intensity. Bed load transport can be investigated by either following the motion of individual particles (Lagrangian approach) or observing the phenomenon at prescribed locations (Eulerian approach). In this paper, the Lagrangian and Eulerian descriptions are merged into a unifying framework that includes definitions for quantities used to describe the kinematics of particle motion, as well as the relationships among these quantities. The alternation of motion and rest is represented by two complementary descriptions: (i) proportion of motion, indicating either the relative time spent in motion by an individual particle or the relative number of moving particles; (ii) persistence of motion, indicating the extent to which the process consists of relatively few long periods of motion or of many short ones. The framework only involves first moments of the key quantities. The conceptual developments are tested against results from an experiment with weak bed load transport, demonstrating the soundness of the approach. From an operational point of view, a Lagrangian observation is difficult to perform, since the particle motion is usually investigated for finite spatial domains (e.g., a measurement window within a laboratory or natural reach). Strategies to overcome such limitations are described, suggesting the possibility of obtaining unbiased mean values for Lagrangian descriptors. The proposed framework can be used in any study aimed at parameterizing the kinematic properties of bed load particles as functions of the hydrodynamic conditions.

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ϑ^{m} ≅ \frac{\sum_{i = 1}^{N} T_{A}^{m} ((), i)}{\sum_{i = 1}^{N} T_{A} ((), i)}

…”

Section: Application To Experimental Resultsmentioning

confidence: 99%

\frac{\overset{true¯}{Q}}{B} = \overset{C}{true} \overset{u}{true} + \overset{C' u'}{true},

Section: Proportion Of Motionmentioning

confidence: 99%

Lagrangian and Eulerian Description of Bed Load Transport

et al. 2018

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“…Previous studies have shown that the retention of bed load is hydraulically initiated as soon as the barrier causes a hydraulic jump upstream underlying generally supercritical flow conditions (Schwindt et al, 2017a(Schwindt et al, , 2017b. Supercritical flow conditions are typical in mountain rivers but not omnipresent (e.g., Heyman et al, 2016). This study is limited to supercritical flow conditions, where the Froude number in the non-constricted channel is generally larger than unity.…”

Section: Design Approach For Permeable Sediment Traps 25mentioning

confidence: 99%

Experimental study of sediment traps permeable for frequent floods

Schwindt

Franca

Reffo

et al. 2017

Preprint

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Abstract. Sediment traps created by partially open torrential barriers are crucial elements for flood protection in alpine regions. 10The trapping of sediment is necessary when intense sediment transport occurs during floods that may endanger urban areas at downstream river reaches. In turn, the unwanted permanent trapping of sediment during small, non-hazardous floods can result in the ecological and morphological depletion of downstream reaches. This study experimentally analyses a new concept for permeable sediment traps. For ensuring the sediment transfer up to small floods, a guiding channel implemented in the deposition area of the sediment trap was studied systematically. The bankfull discharge of the guiding channel corresponds to 15 a dominant morphological discharge. At the downstream end of the guiding channel, a permeable barrier triggers sediment retention and deposition. The permeable barrier consists of a bar screen for mechanical deposition control, superposed to a flow constriction for the hydraulic control. The fail-safe clogging of the barrier and the sediment deposition upstream can be ensured for discharges that are higher than the bankfull discharge of the guiding channel.

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“…The lack of hard information on how particle diffusivity, entrainment and deposition rates vary with flow conditions and sediment supply, see Bohorquez and Ancey [55] and Heyman et al [56], is a clear impediment to the application of movable bed models at the expense of increasing uncertainties.…”

Section: Two-dimensional Shallow Water Modelling Computational Mesh mentioning

confidence: 99%

Paleohydraulic Reconstruction of Modern Large Floods at Subcritical Speed in a Confined Valley: Proof of Concept

Bohorquez

2016

Water

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Abstract:The present study aims to show the accuracy of paleoflood reconstruction techniques based on two-dimensional (2D) hydraulic modelling of a large flood. Using this reconstruction technique, we determined trends in flood stages over time in a regulated river. A stretch of the Guadalquivir River (Southern Spain) was selected as the study site. High-resolution orthophotos and LiDAR (Light Detection and Ranging) elevations were acquired just after modern floods. They were used for the identification and location of stage indicators. In addition, water gradients were estimated from gauging records, documentary information and paleostage indicators (PSIs) in two situations: (i) pre-vegetation encroachment; and (ii) post-vegetation encroachment due to upstream impoundment. Standard two-dimensional, flow depth-averaged equations over fixed beds were used in the hydraulic modelling. In a first stage, long records of instrumental data at gauging stations and documentary evidence of flood levels served to calibrate the input parameters of the hydraulic model. In a second stage, paleoflood signatures within sedimentary and botanical sequences served to verify the flood stages in the numerical simulations not only at the river reach where instrumental data exist but also in the downstream river reach. Interestingly, the rating curve obtained from the combined use of documentary information and imagery was nearly as accurate as gauging measurements. The thoughtful comparison of 2D modelled hydraulic variables against inferred values from PSIs and instrumental data supports the paleoflood reconstruction method over fixed beds. Vegetation encroachment provoked 10% deeper floods at the water discharge of 2000 m 3 ·s −1 , which implied an increase of Manning's roughness coefficient from 0.04 to 0.055 s·m −1/3 in less than 15 years.

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Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Cited by 49 publications

References 111 publications

Lagrangian and Eulerian Description of Bed Load Transport

Lagrangian and Eulerian Description of Bed Load Transport

Experimental study of sediment traps permeable for frequent floods

Paleohydraulic Reconstruction of Modern Large Floods at Subcritical Speed in a Confined Valley: Proof of Concept

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