Pulsations in Bedload Transport Rates Induced by a Longitudinal Sediment Sorting: A Flume Study Using Sand and Gravel Mixtures

1987 ◽  
Vol 69 (1) ◽  
pp. 15 ◽  
Author(s):  
Fujiko Iseya ◽  
Hiroshi Ikeda
Keyword(s):  
Bedload Transport ◽  
Sediment Sorting ◽  
Sand And Gravel ◽  
Flume Study

Bed configuration and microscale processes in alluvial channels

1993 ◽  
Vol 17 (2) ◽  
pp. 123-136 ◽  
Author(s):  
André Robert
Keyword(s):  
Probabilistic Approach ◽  
Field Measurements ◽  
Bedload Transport ◽  
Transport Processes ◽  
Coarse Grained ◽  
Small Scale ◽  
Alluvial Channels ◽  
Gravel Beds ◽  
Sand And Gravel ◽  
Bed Material

Numerous recent studies on fluvial processes, both in Canada and internationally, have focused on small-scale phenomena. Investigations on the characterization of surface roughness in coarse-grained channels and its links with flow resistance and sediment transport processes have been a dominant field of research. Closely related is a second major area of investigation on turbulent flow structures in boundary layers over both sand and gravel beds and their relations with the transport of bed material. Phenomena potentially related to 'bursting' have been shown to control bedload transport processes and the concentration of sediment in suspension. Detailed investigations have also been conducted on the links between flow turbulence, bed material movement, and bed morphology at channel junctions. Finally, selective entrainment and transport of individual coarse particles have been studied from field measurements and laboratory experi ments. Emphasis has been put on bed microtopography, surface structure and texture, and on a probabilistic approach to bedload transport.

Measurement of the spatial distribution of fluvial bedload transport velocity in both sand and gravel

2004 ◽  
Vol 29 (10) ◽  
pp. 1173-1193 ◽  
Author(s):  
Colin D. Rennie ◽  
Robert G. Millar
Keyword(s):  
Spatial Distribution ◽  
Bedload Transport ◽  
Transport Velocity ◽  
Sand And Gravel

Bedload transport of aggregated muddy alluvium from Cooper Creek, central Australia: a flume study

Sedimentology ◽  
1996 ◽  
Vol 43 (5) ◽  
pp. 771-790 ◽  
Author(s):  
J. C. MAROULIS ◽  
G. C. NANSON
Keyword(s):  
Bedload Transport ◽  
Central Australia ◽  
Flume Study

scholarly journals Dependence of sediment sorting on bedload transport phase in a river meander

2018 ◽  
Vol 43 (10) ◽  
pp. 2077-2088 ◽  
Author(s):  
Albert Rovira ◽  
Francisco Núñez-González ◽  
Carles Ibañez
Keyword(s):  
Bedload Transport ◽  
Sediment Sorting ◽  
Transport Phase

scholarly journals Opposite hysteresis of sand and gravel transport upstream and downstream of a bifurcation during a flood in the River Rhine, the Netherlands

2007 ◽  
Vol 86 (3) ◽  
pp. 273-285 ◽  
Author(s):  
M.G. Kleinhans ◽  
A.W.E. Wilbers ◽  
W.B.M. ten Brinke
Keyword(s):  
Sediment Transport ◽  
Transport Rate ◽  
River Rhine ◽  
Rhine River ◽  
Bed Sediment ◽  
Hydraulic Roughness ◽  
Meandering River ◽  
Sediment Sorting ◽  
Sand And Gravel ◽  
Clockwise Hysteresis

AbstractAt river bifurcations water and sediment is divided among the downstream branches. Prediction of the sediment transport rate and division thereof at bifurcations is of utmost importance for understanding the evolution of the bifurcates for short-term management purposes and for long-term fluvial plain development. However, measured sediment transports in rivers rarely show a uniquely determined relation with hydrodynamic parameters. Commonly a hysteresis is observed of transport rate as a function of discharge or shear stress which cannot be explained with the standard sediment transport predictor approach. The aim of this paper is to investigate the causes of hysteresis at a bifurcation of the lower Rhine river, a meandering river with stable banks, large dunes during flood, and poorly sorted bed sediment. The hydrodynamics and bed sediment transport were measured in detail during a discharge wave with a recurrence interval larger than 10 years. Surprisingly, the hysteresis in bedload against discharge was in the opposite direction upstream and downstream of the bifurcation. The upstream clockwise hysteresis is caused by the lagging development of dunes during the flood. The counter-clockwise hysteresis downstream of the bifurcation is caused by a combination of processes in addition to dune lagging, namely 1) formation of a scour zone upstream of the bifurcation, causing a migrating fine sediment wave, and 2) vertical bed sorting of the bed sediment by dunes with avalanching lee-sides, together leading to surface-sediment fining and increased transport during and after the flood. These findings lead to challenges for future morphological models, particularly for bifurcations, which will have to deal with varying discharge, sediment sorting in the channel bed, lagging dunes and related hydraulic roughness.

The influence of gravel mixed with sand on the formation and development of ripples.

2020 ◽  
Author(s):  
Katrien Van Landeghem ◽  
Irinios Yiannoukos ◽  
Connor McCarron ◽  
Jacob Morgan ◽  
Barney Clayton-Smith
Keyword(s):  
Sediment Transport ◽  
Critical Shear Stress ◽  
Bedload Transport ◽  
Migration Rates ◽  
Ripple Formation ◽  
Shelf Seas ◽  
Flow Speeds ◽  
And Migration ◽  
Sand And Gravel ◽  
Sediment Mixtures

<p>Coarse and bimodal sediment mixtures like sand and gravel are common in palaeo-glaciated shelf seas and in coastal environments. Their presence leads to more complex sediment transport and morphodynamic processes, depending on the ratio of sand to gravel in the bed. With increased pressure on our near-and offshore sea beds, there is a growing need to more accurately model sediment transport and bedform dynamics with an increasing focus on bimodal sand-gravel sediment mixtures. Revisiting the quantification of the hiding-exposure (HE) effect highlighted how differently sized grains in a bimodal mixture modify each other’s threshold of motion. The critical shear stress needed to mobilise the sand and gravel fractions increased by up to 75% and decreased by up to 64% respectively, compared to that needed to mobilise well-sorted sediment of similar size. Implementation of this newly quantified HE correction in current-and wave-driven models illustrated that its influence on bedload transport rates and bed morphodynamics was greatest for mixtures where gravel percentage ranges between 10 and 20 %. Laboratory experiments were therefore conducted to investigate ripple formation and bed dynamics in mixtures with gravel percentage between 0 and 25%. The development of initial bedforms was quicker in sand-gravel mixtures compared to those developed in pure sand, whilst final heights and migration rates of the developed ripples decreased with increasing fraction of gravel in the bed. During this presentation, a full comparison will be made of the morphology and “down-core” sedimentary properties of ripples formed at different flow speeds. If we want to use our seabeds cost-effectively and sustainably, we need a better understanding on the influence of a decreased mobilisation of the finer fractions and an increased mobilisation of the coarser fraction on the dynamics of beds with a bimodal sediment composition.</p>

New Sand and Gravel Driers

1876 ◽  
Vol 1 (7supp) ◽  
pp. 101-101
Author(s):  
S. S. Daish
Keyword(s):  
Sand And Gravel

Oscillatory Bedload Transport Studies by Imaging of Tracers

1993 ◽  
Author(s):  
E.L. Gallagher ◽  
R.J. Seymour
Keyword(s):  
Bedload Transport ◽  
Transport Studies
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