Flume Experiments on the Erosive Energy of Bed Load Impacts on Rough and Planar Beds

Abstract. The transportation of bank-collapsed materials is a key issue among river evolution processes. In this study, a series of flume experiments were conducted to monitor riverbank collapse processes and to explore the regularity of transportation for cohesive collapsed materials. The collapsed materials, both the bed and suspended loads, that transformed from collapsed materials were intensively evaluated under experimental conditions. The results showed that the collapsed materials contributed to 12～20 % sedimentation in situ, 8～14 % suspended loads and 70～80 % bed loads. In addition, the bed load motion efficiency coefficient (eb), suspended load motion efficiency coefficient (es) and sediment carrying capacity factor (U3/gRω) were introduced to describe the transportation of collapsed materials in terms of energy dissipation. This research provides theoretical and practical benefits for predicting channel evolution processes.

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Prediction of interaction between a side overflow and bed-load transport in a channel with semi-empirical approaches

Canadian Journal of Civil Engineering ◽

10.1139/l09-105 ◽

2009 ◽

Vol 36 (11) ◽

pp. 1755-1763 ◽

Cited By ~ 2

Author(s):

Burkhard Rosier ◽

Jean-Louis Boillat ◽

Anton J. Schleiss

Keyword(s):

Engineering Practice ◽

Bed Load ◽

Flume Experiments ◽

Load Transport ◽

Bed Load Transport ◽

Input Variables ◽

Side Weirs ◽

Semi Empirical ◽

Protection Engineering

Side weirs are free overflow regulation and diversion structures commonly encountered in flood protection engineering. The lateral loss of water reduces the bed-load transport capacity in the main channel, leading to local sediment deposition near the side overflow. As a consequence, the design overflow is increased in an uncontrolled way. Since this flow–sediment interaction in such a channel has not been studied so far, systematic flume experiments have been performed. Based on these experiments, a two-dimensional empirical model to describe the longitudinal evolution of the aggraded channel reach near the weir has been developed. In addition, a simple and straightforward approach for direct estimation of the side overflow in presence of bed-load transport has been established. To be generally applicable in engineering practice, all input variables are expressed in terms of dimensionless parameters. Finally, the application of the models is demonstrated in a case study on the Rhone River in Switzerland.

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Flume Experiments on Gravel Bed Load Transport in Unsteady Flow—Preliminary Results

Hydrodynamic and Mass Transport at Freshwater Aquatic Interfaces - GeoPlanet: Earth and Planetary Sciences ◽

10.1007/978-3-319-27750-9_18 ◽

2016 ◽

pp. 221-233 ◽

Cited By ~ 3

Author(s):

Magdalena M. Mrokowska ◽

Paweł Rowiński ◽

Leszek Książek ◽

Andrzej Strużyński ◽

Maciej Wyrębek ◽

...

Keyword(s):

Unsteady Flow ◽

Bed Load ◽

Flume Experiments ◽

Preliminary Results ◽

Gravel Bed ◽

Load Transport ◽

Bed Load Transport

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Laboratory flume experiments with the Swiss plate geophone bed load monitoring system: 2. Application to field sites with direct bed load samples

Water Resources Research ◽

10.1002/2016wr019283 ◽

2016 ◽

Vol 52 (10) ◽

pp. 7760-7778 ◽

Cited By ~ 17

Author(s):

Carlos R. Wyss ◽

Dieter Rickenmann ◽

Bruno Fritschi ◽

Jens M. Turowski ◽

Volker Weitbrecht ◽

...

Keyword(s):

Monitoring System ◽

Bed Load ◽

Flume Experiments ◽

Laboratory Flume ◽

Load Monitoring ◽

System 2

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Numerical Dispersion of Bed Load in a 1D Model Mimics Physical Flume Results

10.5194/egusphere-egu2020-20357 ◽

2020 ◽

Author(s):

Travis Dahl ◽

Stanford Gibson ◽

Ian Floyd ◽

Alejandro Sanchez

Keyword(s):

Active Layer ◽

Transport Model ◽

Numerical Dispersion ◽

Bed Load ◽

Army Corps ◽

Active Layer Thickness ◽

Army Corps Of Engineers ◽

Flume Experiments ◽

Hydraulics Laboratory ◽

The U.S

<p>The longitudinal dispersion of bed load particles as they move downstream in a river is relevant both to cases of polluted sediment and pulses of sediment released during reservoir flushing events or dam removals.&#160; To quantify the rate of bed-load dispersion, researchers with the U.S. Army Corps of Engineers conducted a series of flume experiments using successive additions of different-colored sediment in a 22m x 0.9m, upstream-fed, tilting flume at the U.S. Engineer Research and Development Center's (ERDC) Coastal and Hydraulics Laboratory.&#160; Here we show that longitudinal bed-load dispersion can be accurately modeled in a one-dimensional sediment transport model (HEC-RAS) that does not explicitly simulate dispersion.&#160; We accomplished this by adjusting the active layer thickness and the bed-load depositional exchange increment.&#160; The bed-load depositional exchange increment sets the ratio of active layer vs. bed-load material that are mixed into the bed during deposition. &#160;The optimal parameters varied between the flume experiments, but smaller active layer thicknesses generally performed better.&#160;</p>

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Grain shape effects in bed load sediment transport

10.31223/x55033 ◽

2021 ◽

Author(s):

Eric Deal ◽

Jeremy Venditti ◽

Santiago Benavides ◽

Ryan Bradley ◽

Qiong Zhang ◽

...

Keyword(s):

Sediment Transport ◽

Grain Shape ◽

Sediment Flux ◽

Bed Load ◽

Flume Experiments ◽

Natural Sediment ◽

Shape Effects ◽

Load Transport ◽

Bed Load Transport ◽

Load Sediment

Bed load sediment transport, in which wind or water flowing over a bed of sediment causes grains to roll or hop along the bed, is a critically important mechanism in contexts ranging from river restoration to planetary exploration. Despite its widespread occurrence, predictions of bed load sediment flux are notoriously imprecise. Many studies have focused on grain size variability as a source of uncertainty, but few have investigated the role of grain shape, even though shape has long been suspected to influence transport rates. Here we show that grain shape can modify bed load transport rates by an amount comparable to the scatter in many sediment transport data sets. We develop a theory that accounts for grain shape effects on fluid drag and granular friction and predicts that the onset and efficiency of bed load transport depend on the mean drag coefficient and bulk friction coefficient of the transported grains. Laboratory flume experiments using a variety of grain shapes confirm these predictions. We propose a shape-independent sediment transport law that collapses our experimental measurements onto a single trend, allowing for more accurate predictions of sediment transport and helping reconcile theory developed for spherical particle transport with the behavior of natural sediment grains.

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Bulk drag coefficient of a subaquatic vegetation subjected to irregular waves: Influence of Reynolds and Keulegan-Carpenter numbers

La Houille Blanche ◽

10.1051/lhb/2020015 ◽

2020 ◽

pp. 34-42

Author(s):

Thibault Chastel ◽

Kevin Botten ◽

Nathalie Durand ◽

Nicole Goutal

Keyword(s):

Drag Coefficient ◽

Wave Height ◽

Wave Attenuation ◽

Empirical Relationship ◽

Breaking Waves ◽

Irregular Waves ◽

Geometrical Parameters ◽

Flume Experiments ◽

Seagrass Meadows ◽

Artificial Vegetation

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs, Tp, water depth hw) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio (< 0.2) the wave attenuation is negligible. From each experiment, a bulk drag coefficient has been extracted following the energy dissipation model for irregular non-breaking waves developed by Mendez and Losada (2004). This model, based on the assumption that the energy loss over the species meadow is essentially due to the drag force, takes into account both wave and vegetation parameter. Finally, we found an empirical relationship for Cd depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

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