Bed load transport of mixed size sediment: Fractional transport rates, bed forms, and the development of a coarse bed surface layer

It is very important for reservoir management to estimate the sedimentation amount deposited in a reservoir. Firstly, the formula for estimating the bed load transport rate in the bed of sand waves of prototype by model experiment was derived based on the similarity of grain Froude number; Secondly, several model experiments that the bed forms is similar with the prototype were carried, and the formula was verified. As a result, when the ratio of grain diameter in the prototype and model is great enough, and the bed forms in the model is similar with that in the prototype, a satisfactory result can be obtained by using the estimation formula for estimating the bed load transport rate of the prototype that sand waves occur in the bed.

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The Application of Radioactive Tracers for Determination of Bed-Load Transport in Alluvial Rivers

Hydrology Research ◽

10.2166/nh.1980.0018 ◽

1980 ◽

Vol 11 (3-4) ◽

pp. 133-144 ◽

Cited By ~ 2

Author(s):

Thorkild Thomsen

Keyword(s):

Radioactive Isotopes ◽

Bed Load ◽

Alluvial Rivers ◽

Tracer Particles ◽

Bed Forms ◽

Load Transport ◽

Bed Load Transport ◽

Tracer Methods ◽

The Difference

Radioactive isotopes have been applied for determining the transport rate of bed load in an alluvial river on the basis of: centroid velocity of the tracer particles, size and material-transporting width of mobile layer. These parameters were found by detailed measurements in the field. Computed values were produced on the basis of Engelund and Fredsøe's model on sediment transport (1976) and on the propagation of bed forms. When comparing measured and computed values, the difference was about 25%. Finally, the applicability of tracer methods for solving practical problems is discussed.

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Modelling the formation of shoreface-connected sand ridges on storm-dominated inner shelves

Journal of Fluid Mechanics ◽

10.1017/s0022112001004815 ◽

2001 ◽

Vol 441 ◽

pp. 169-193 ◽

Cited By ~ 58

Author(s):

D. CALVETE ◽

A. FALQUES ◽

H. E. DE SWART ◽

M. WALGREEN

Keyword(s):

Suspended Load ◽

Bed Load ◽

Small Perturbations ◽

Physical Mechanisms ◽

Sand Ridges ◽

Bed Forms ◽

Load Transport ◽

Bed Load Transport ◽

And Migration ◽

Mean Current

A morphodynamic model is developed and analysed to gain fundamental understanding of the basic physical mechanisms responsible for the characteristics of shoreface-connected sand ridges observed in some coastal seas. These alongshore rhythmic bed forms have a horizontal lengthscale of order 5 km and are related to the mean current along the coast: the seaward ends of their crests are shifted upstream with respect to where they are attached to the shoreface. The model is based on the two-dimensional shallow water equations and assumes that the sediment transport only takes place during storms. The flux consists of a suspended-load part and a bed-load part and accounts for the effects of spatially non-uniform wave stirring as well as for the preferred downslope movement of sediment. The basic state of this model represents a steady longshore current, driven by wind and a pressure gradient. The dynamics of small perturbations to this state are controlled by a physical mechanism which is related to the transverse bottom slope. This causes a seaward deflection of the current over the ridges and the loss of sediment carrying capacity of the flow into deeper water. The orientation, spacing and shape of the modelled ridges agree well with field observations. Suspended-load transport and spatially non-uniform wave stirring are necessary in order to obtain correct e-folding timescales and migration speeds. The ridge growth is only due to suspended-load transport whereas the migration is controlled by bed-load transport.

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Effect of Coarse Surface Layer on Bed-Load Transport

Journal of Hydraulic Engineering ◽

10.1061/(asce)0733-9429(2007)133:11(1192) ◽

2007 ◽

Vol 133 (11) ◽

pp. 1192-1205 ◽

Cited By ~ 60

Author(s):

James C. Bathurst

Keyword(s):

Surface Layer ◽

Bed Load ◽

Load Transport ◽

Coarse Surface ◽

Bed Load Transport

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NUMERICAL MODEL TO SIMULATE THE EROSION ON THE SLOPE DUE TO OVERTOPPING

Science and Technology Development Journal ◽

10.32508/stdj.v13i3.2156 ◽

2010 ◽

Vol 13 (3) ◽

pp. 78-87

Author(s):

Hoai Cong Huynh

Keyword(s):

Numerical Model ◽

Flow Model ◽

Bed Load ◽

Experiment Data ◽

Step Method ◽

Morphological Model ◽

Load Transport ◽

Bed Load Transport ◽

The Finite Difference Method ◽

Good Agreement

The numerical model is developed consisting of a 1D flow model and the morphological model to simulate the erosion due to the water overtopping. The step method is applied to solve the water surface on the slope and the finite difference method of the modified Lax Scheme is applied for bed change equation. The Meyer-Peter and Muller formulae is used to determine the bed load transport rate. The model is calibrated and verified based on the data in experiment. It is found that the computed results and experiment data are good agreement.

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