scholarly journals A Shear Reynolds Number-Based Classification Method of the Nonuniform Bed Load Transport

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 73 ◽  
Author(s):  
Gergely T. Török ◽  
János Józsa ◽  
Sándor Baranya
Keyword(s):  
Reynolds Number ◽  
Sediment Transport ◽  
Comparative Assessment ◽  
Bed Load ◽  
Laboratory Measurements ◽  
Strong Variation ◽  
Load Transport ◽  
Bed Load Transport ◽  
Novel Method ◽  
Bed Material

The aim of this study is to introduce a novel method which can separate sand- or gravel-dominated bed load transport in rivers with mixed-size bed material. When dealing with large rivers with complex hydrodynamics and morphodynamics, the bed load transport modes can indicate strong variation even locally, which requires a suitable approach to estimate the locally unique behavior of the sediment transport. However, the literature offers only few studies regarding this issue, and they are concerned with uniform bed load. In order to partly fill this gap, we suggest here a decision criteria which utilizes the shear Reynolds number. The method was verified with data from field and laboratory measurements, both performed at nonuniform bed material compositions. The comparative assessment of the results show that the shear Reynolds number-based method operates more reliably than the Shields–Parker diagram and it is expected to predict the sand or gravel transport domination with a <5% uncertainty. The results contribute to the improvement of numerical sediment transport modeling as well as to the field implementation of bed load transport measurements.

scholarly journals A Shear Reynolds Number Based Investigation Method of the Bed Load Transport in Large Rivers with Complex Morphodynamics

2018 ◽  
Author(s):  
Gergely T. Török ◽  
János Józsa ◽  
Sándor Baranya
Keyword(s):  
Reynolds Number ◽  
Sediment Transport ◽  
Measurement Data ◽  
Large Rivers ◽  
Engineering Practice ◽  
Bed Load ◽  
Load Transport ◽  
Bed Load Transport ◽  
Novel Method ◽  
Bed Material

The aim of this study is to introduce a novel method which can separate sand or gravel dominated bed load transport in rivers with mixed-size bed material. In engineering practice, the Shields-Parker diagram could be used for such purposes, however, the method has certain applicability limits, due to the fact that it is based on uniform bed material and provides information rather on river-scale, instead of reach or local scale. When dealing with large rivers with complex hydrodynamics and morphodynamics the bed load transport modes can also indicate strong variation even locally, which requires a more suitable approach to estimate the locally unique behavior of the sediment transport. Here, we suggest that the decision criteria utilizes the shear Reynolds number (Re*). The method was verified against field and laboratory measurement data, both performed at non-uniform bed material compositions. The comparative assessment of the results show that the shear Reynolds number based method operates more reliably than the Shields-Parker diagram and it is expected to predict the sand or gravel transport domination with a &lt; 5% uncertainty. The introduced results can greatly contribute to the improvement of numerical sediment transport modeling as well as to the field implementation of bed load transport measurements.

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.

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 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 BED LOAD TRANSPORT DUE TO NON-LINEAR WAVE MOTION

1988 ◽  
Vol 1 (21) ◽  
pp. 133 ◽  
Author(s):  
Hitoshi Tanaka
Keyword(s):  
Sediment Transport ◽  
Wave Motion ◽  
Surf Zone ◽  
Function Theory ◽  
Transport Rate ◽  
Bed Load ◽  
Linear Wave ◽  
Wave Flume ◽  
Load Transport ◽  
Bed Load Transport

The bed load transport rate due to wave motion is measured in a wave flume. The modified stream function theory of the author ( Tanaka (1988) ) is applied to the formulation of the sediment transport rate in order to include the non-linearity. The proposed formula predicts well except near the surf zone where the effect of the acceleration plays an important role.

On the formation of ripples on an erodible bed

1984 ◽  
Vol 144 ◽  
pp. 177-190 ◽  
Author(s):  
B. Mutlu Sumer ◽  
Mehmet Bakioglu
Keyword(s):  
Reynolds Number ◽  
Stability Analysis ◽  
Linear Stability Analysis ◽  
Present Theory ◽  
Bed Load ◽  
Wave Stability ◽  
Load Transport ◽  
Bed Load Transport ◽  
Limiting Values ◽  
Good Agreement

A linear stability analysis is presented of both hydraulically smooth and transitional flows over an erodible bed. The present theory is developed to account for the formation of ripples. It is essentially an extension of the theory of Richards (1980) to include the effect of viscosity upon the bed wave stability. The theory takes into consideration that the formation of ripples does not depend on flow depths, and that only the bed-load transport is involved in the formation of ripples. The effect of gravity is included in the analysis through the local inclination of the wavy bed surface. The results show that the bed is unstable (i.e. ripples exist) when the grain Reynolds number is less than a certain value. The limiting values of the grain Reynolds number for ripple existence obtained through present analysis are found to be in good agreement with observations.

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.

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