scholarly journals A Sediment Transport Model for Straight Alluvial Channels

1976 ◽  
Vol 7 (5) ◽  
pp. 293-306 ◽  
Author(s):  
Frank Engelund ◽  
Jørgen Fredsøe
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Suspended Load ◽  
Empirical Models ◽  
Bed Load ◽  
Alluvial Channels ◽  
Physical Processes ◽  
Sediment Transport Model ◽  
Load Transport ◽  
Bed Load Transport

The paper presents a simple mathematical model for sediment transport in straight alluvial channels. The model, which is based on physical ideas related to those introduced by Bagnold (1954), was originally developed in two steps, the first describing the bed load transport (Engelund 1975) and the second accounting for the suspended load (Fredsøe and Engelund 1976). The model is assumed to have two advantages as compared with empirical models, first it is based on a description of physical processes, secondly it gives some information about the quantity and size of the sand particles in suspension and the bed particles.

scholarly journals Regression analysis between sediment transport rates and stream discharge for the Nestos River, Greece

2013 ◽  
Vol 14 (3) ◽  
pp. 362-370
Keyword(s):  
Sediment Transport ◽  
Suspended Load ◽  
Bed Load ◽  
Regression Curve ◽  
Degree Polynomial ◽  
Stream Discharge ◽  
Nestos River ◽  
Polynomial Curve ◽  
Load Transport ◽  
Bed Load Transport

Systematic measurements of sediment transport rates and water discharge were conducted in the Nestos River (Greece), at a place located between the outlet of Nestos River basin and the river delta. This basin area is about 838 km2 and lies downstream of the Platanovrysi Dam. Separate measurements of bed load transport and suspended load transport were performed at certain cross sections of the Nestos River. In this study, relationships between sediment transport rates and stream discharge for the Nestos River are presented. A nonlinear regression curve (4th degree polynomial curve; r2 equals 0.62) between bed load transport rates and stream discharge, on the basis of 63 measurements, was developed. In addition, a nonlinear regression curve (5th degree polynomial curve; r2 equals 0.95) between suspended load transport rates and stream discharge, on the basis of 65 measurements, was developed. The relatively high r2 values indicate that both bed load transport rates and, especially, suspended load transport rates can be predicted as a function of the stream discharge in the Nestos River. However, the reliability of the regression equations would have been higher if more measured data were available.

scholarly journals Analisa Angkutan Sedimen Pada Hulu Bendung Aepodu Kabupaten Konawe Selatan

2021 ◽  
Vol 2 (1) ◽  
pp. 1-7
Author(s):  
Ramadhan Hidayat Putra ◽  
Amad Syarif Syukri ◽  
Catrin Sudarjat ◽  
Vickky Anggara Ilham
Keyword(s):  
Sediment Transport ◽  
River Flow ◽  
Suspended Load ◽  
Bedload Transport ◽  
Bed Load ◽  
Average Flow ◽  
Load Transport ◽  
Bed Load Transport ◽  
Transport Analysis

Research on Aepodu Weir Sediment Transport Analysis in South Konawe District, based on observations in the field, Aepodu Weir hasa sediment buildup that has now exceeded the height of the weirlight house. The purpose of the study was to analyze the magnitudeof Aepodu river flow and to analyze the amount of sedimenttransport that occurred in the Aepodu dam. The method used todetermine the amount of bed load transport uses stchoklitscht, whilefor transporting suspended load using forcheimer.The results of the analysis of the average flow of the Aepodu riverwere 3,604 m3/ second. Sediment transport that occurs in Aepoduweir is Bedload transport (Qb) of 291625.771 tons / year, andsuspended load transport (Qs) of 16972,423 tons / year, so that thetotal sediment transport (QT) is 308598,194 tons / year.

scholarly journals Two-Dimensional Numerical Simulation Study on Bed-load Transport in Fluctuating Backwater Area: A Case-Study Reservoir in China

2018 ◽  
Author(s):  
Ming Luo ◽  
Heli Yu ◽  
Er Huang ◽  
Rui Ding ◽  
Xin Lu
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Longitudinal Section ◽  
Bed Load ◽  
Two Dimensional ◽  
River Bed ◽  
Reservoir Drawdown ◽  
Load Transport ◽  
Bed Load Transport ◽  
Volume Method

Numerical modeling of sedimentation and erosion in reservoirs is an active field of reservoir research. However, simulation of bed-load transport phenomena has rarely been applied to other water bodies, in particular, the fluctuating backwater area. This is because the complex morphological processes between hydrodynamics and sediment transport are generally challenging to accurately predict. In this study, the refinement and application of a two-dimensional shallow-water and bed-load transport model to the fluctuating backwater area is described. The model employs the finite volume method of the Godunov scheme and saturated sediment transport equations. The model was verified against experimental data of a scaled physical model. It was then applied to actual reservoir operation, including reservoir storage, reservoir drawdown and continuous flood process, to predict the morphology of reservoir sedimentation and sediment transport rates and bed level changes in the fluctuating backwater area. It was found that the location and morphology of sedimentation effected by the downstream water level results in random evolution of the river bed, and bed-load sedimentation is transported from upstream to downstream with the slope of the longitudinal section of the river bed generally reduced. Moreover, the sediment is mainly deposited in the main channel and the elevation difference between the riverbank and channel decreases gradually.

scholarly journals A Modified Sediment Transport Model for Natural Streams

1982 ◽  
Vol 13 (2) ◽  
pp. 79-92
Author(s):  
Thorkild Thomsen
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Alluvial Rivers ◽  
Sediment Transport Model ◽  
Tracer Particles ◽  
Natural Streams ◽  
Load Transport ◽  
Bed Load Transport ◽  
Particle Velocities

In an earlier investigation of the behaviour of tracer particles for determination of bed load transport in an alluvial stream (Thomsen 1980), specific records were taken of the particle velocities in the upper bed layer. These data aroused the interest for more detailed investigations. The result of the measured surface particle velocities with radioactive tracers, performed in five locatities with different hydraulic conditions in natural alluvial rivers, has been used for determination of the relation UG/Uf'vs. √θ'/θ0. The obtained results have been inserted in the parameters of Engelund and Fredsøe's sediment transport model (1976) and compared with experimental data (Guy et al. 1966). Some reservations and methods for possible improvements of the sediment transport model are finally discussed.

QUASI-THREE-DIMENSIONAL MATHEMATICAL MODELING OF MORPHOLOGICAL PROCESSES BASED ON EQUILIBRIUM SEDIMENT TRANSPORT

2000 ◽  
Vol 11 (07) ◽  
pp. 1425-1436 ◽  
Author(s):  
MY. M. CHARAFI ◽  
A. SADOK ◽  
A. KAMAL ◽  
A. MENAI
Keyword(s):  
Sediment Transport ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Suspended Load ◽  
Bed Load ◽  
Change Rate ◽  
Sediment Mass ◽  
Load Transport ◽  
Bed Load Transport ◽  
Morphological Processes

A quasi-three-dimensional mathematical model has been developed to study the morphological processes based on equilibrium sediment transport method. The flow velocities are computed by a two-dimensional horizontal depth-averaged flow model (H2D) in combination with logarithmic velocity profiles. The transport of sediment particles by a flow water has been considered in the form of bed load and suspended load. The bed load transport rate is defined as the transport of particles by rolling and saltating along the bed surface and is given by the Van Rijn relationship (1987). The equilibrium suspended load transport is described in terms of an equilibrium sediment concentration profile (ce) and a logarithmic velocity (u). Based on the equilibrium transport, the bed change rate is given by integration of the sediment mass-balance equation. The model results have been compared with a Van Rijn results (equilibrium approach) and good agreement has been found.

scholarly journals A MULTIPLE-SIZED TRANSPORT FORMULA FOR NONUNIFORM SEDIMENTS UNDER CURRENT AND WAVES

2012 ◽  
Vol 1 (33) ◽  
pp. 34 ◽  
Author(s):  
Weiming Wu ◽  
Qianru Lin
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Size Composition ◽  
Suspended Load ◽  
Transport Rate ◽  
Bed Load ◽  
Nonuniform Sediment ◽  
Load Transport ◽  
Bed Load Transport ◽  
Bed Material

Nonuniform sediment transport exhibits difference from uniform sediment, even when the mean grain size is the same for both cases. The hiding, exposure, and armoring among different size fractions in the nonuniform bed material may significantly affect sediment transport, morphological change, bed roughness, wave dissipation, etc. It is necessary to develop multiple-sized sediment transport capacity formula to improve the accuracy and reliability of coastal analysis tools. The Wu et al. (2000) formula, which was developed for river sedimentation, is herein extended to calculate multiple-sized sediment transport under current and waves for coastal applications. This formula relates bed-load transport to the grain shear stress and suspended-load transport to the energy of the flow system. It considers the effect of bed material size composition in the hiding and exposure correction factor, which is omitted in many other existing formulas. Methods have been developed in this study to determine the bed shear stress due to waves only and combined current and waves, and in turn to compute the bed-load and suspended-load transport rates using the Wu et al. (2000) formula without changing its original formulation. The enhanced bed-load formula considers the effect of wave asymmetry on sediment transport, calculates the onshore and offshore bed-load transport rates separately and then derives the net transport rate, whereas the enhanced suspended-load formula calculates only the net transport rate due to the limit of available data. The formula has been tested using the single-sized and multiple-sized sediment transport data sets. The formula provides reliable predictions in both fractional and total transport rates. More than half of the test cases are predicted within a factor of 2 of the measured values, and more than 90% of the cases are within a factor of 5. This accuracy is generally reasonable for sediment transport under current and waves, which is very complex and little understood.

The ratio of mechanical to chemical denudation in alluvial systems, derived from geochemical mass balance

1993 ◽  
Vol 84 (1) ◽  
pp. 73-78 ◽  
Author(s):  
A. D. Stewart
Keyword(s):  
Mass Balance ◽  
Chemical Weathering ◽  
Amazon Basin ◽  
Source Area ◽  
Large River ◽  
Suspended Load ◽  
Bed Load ◽  
Load Transport ◽  
Bed Load Transport ◽  
Dissolved Load

ABSTRACTMass balance equations are derived which link the ratios Ts/ (suspended load/dissolved load from chemical weathering) and Tb/Ts (bed load/suspended load), with any two geochemical components present in the source rock and the alluvial system. If the dissolved load is unknown the ratios can be estimated from the relatively insoluble silica and alumina. The ratio Ts/, which for large river basins depends on climate and relief, can thus potentially be determined from ancient alluvial sequences.The equations help define the source composition of a group of 13 modern rivers for which Ts, and alluvial geochemistry are known. These rivers together drain 27% of the continental surface. For a source area with the average continental sandstone to shale ratio of 0·6 the observed average value of Ts/ is obtained when limestone, sandstone and shale are present in the proportions 6·7:21·6:35·7. The figure of 64% sediment in the source area is very similar to the 66% determined by Blatt and Jones (1975) from geological maps of the continents. The equations also show that average bed load transport rate into these 13 basins is about 27% of total transport, and into the Amazon basin about 37%. Bed load transport rates out of the basins, into the sea, are relatively very small.

scholarly journals Evaluation of an acoustic Doppler technique for bed-load transport measurements in sand-bed Rivers

2018 ◽  
Vol 40 ◽  
pp. 02053 ◽  
Author(s):  
S. Conevski ◽  
A. Winterscheid ◽  
N. Ruther ◽  
M. Guerrero ◽  
C. Rennie
Keyword(s):  
Transport Model ◽  
Transport Rate ◽  
Qualitative Assessment ◽  
Bed Load ◽  
Apparent Velocity ◽  
Digital Cameras ◽  
Statistical Correlations ◽  
Hydraulic Conditions ◽  
Load Transport ◽  
Bed Load Transport

The bottom tracking (BT) feature of the acoustic Doppler current profilers (ADCP) have emerged as a promising technique in evaluating the bed load. Strong statistical correlations are reported between the ADCP BT velocity and the transport rate obtained by physical sampling or dune tracking; however, these relations are strictly site-specific and a local calibration is necessary. The direct physical sampling is very labor intensive and it is prone to high instrument uncertainty. The aim of this work is to develop a methodology for evaluating the bed load transport using commercial ADCPs without calibration with physical samples. Relatively long stationary measurements were performed in a sand-bed and sand gravel rivers, using three different ADCPs working at 3MHz, 1.2MHz and 0.6MHz. Simultaneously, bed load samples were collected with physical samplers, and the riverbed was closely observed with digital cameras mounted on the samplers. It is demonstrated that the kinematic transport model can yield a relatively good estimate of the transport rate by directly using filtered apparent velocity, the knowledge of the hydraulic conditions and instrument-related calibration coefficients. Additionally, the ADCP data can help in qualitative assessment of the physical sampling. Future investigation of the backscattering echo and further confirmation of the BT apparent velocity should be performed in laboratory-controlled conditions.

Effect of Impoundment and Diversion on the Sediment Budget and Nearshore Sedimentation of Southern Indian Lake

1984 ◽  
Vol 41 (4) ◽  
pp. 567-578 ◽  
Author(s):  
R. E. Hecky ◽  
G. K. McCullough
Keyword(s):  
Fine Particles ◽  
Suspended Load ◽  
Constituent Particle ◽  
Shoreline Erosion ◽  
Bed Load ◽  
Particle Sizes ◽  
Fine Silt ◽  
Load Transport ◽  
Bed Load Transport ◽  
Clay Aggregates

Shoreline erosion added an annual average of 4 × 106 t of mineral sediment per year to Southern Indian Lake (postimpoundment area, 2391 km2) during the first 3 yr of impoundment. This erosion increased sedimentary input to the lake by a factor of 20. The lake retained 90% of this eroded material within its basin, and 80–90% of the retained material was deposited nearshore. Despite the production of extremely fine constituent particle sizes, eroding shorelines generated predominantly large clay aggregates, initially transported offshore as bed load. During bed load transport, abrasion of clay aggregates produced fine particles that became suspended. Over 80% of the suspended load is lost to outflows from the lake because the suspended load is primarily fine silt and clay-sized particles, most of which do not settle even under winter ice cover. The extensive nearshore clay aggregate deposits are temporary, and net deposition in these areas will change to net erosion when input of sediment from eroding shorelines ceases. The effects of shoreline erosion on the lake's sediment regime will persist for decades.

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