A method is presented which enables the computation of the bed-load transport as the product of the saltation height, the particle velocity and the bed-load concentration. The equations of motions for a solitary particle are solved numerically to determine the saltation height and particle velocity. Experiments with gravel particles (transported as bed load) are selected to calibrate the mathematical model using the lift coefficient as a free parameter. The model is used to compute the saltation heights and lengths for a range of flow conditions. The computational results are used to determine simple relationships for the saltation characteristics. Measured transport rates of the bed load are used to compute the sediment concentration in the bed-load layer. A simple expression specifying the bed-load concentration as a function of the flow and sediment conditions is proposed. A verification analysis using about 600 (alternative) data shows that about 77% of the predicted bed-load-transport rates are within 0.5 and 2 times the observed values.

Sediment transport; Part I, Bed load transport

A method is presented that makes the classification of bed forms, the prediction of the bed‐form dimensions and the effective hydraulic roughness of the bed forms feasible. The proposed relationships are based on the analysis of reliable flume and field data. A verification analysis using about 1,500 (alternative) reliable flume and field data shows good results in predicting the hydraulic roughness (friction factor). For field conditions, the proposed method yields considerably better results than previously proposed methods, which are reviewed here. The proposed method has also been used to predict the flow depth and the total bed‐material load.

Sediment Transport, Part III: Bed Forms and Alluvial Roughness

Attention is given to the properties of sediment beds over the full range of conditions (silts to gravel), in particular the effect of fine silt on the bed composition and on initiation of motion (critical conditions) is discussed. High-quality bed-load transport data sets are identified and analyzed, showing that the bed-load transport in the sand range is related to velocity to power 2.5. The bed-load transport is not much affected by particle size. The prediction of bed roughness is addressed and the prediction of bed-load transport in steady river flow is extended to coastal flow applying an intrawave approach. Simplified bed-load transport formulas are presented, which can be used to obtain a quick estimate of bed-load transport in river and coastal flows. It is shown that the sediment transport of fine silts to coarse sand can be described in a unified model framework using fairly simple expressions. The proposed model is fully predictive in the sense that only the basic hydrodynamic parameters (dep...

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Unified view of sediment transport by currents and waves. I: Initiation of motion, bed roughness, and bed-load transport

Closure of "Sediment Transport, Part III: Bed Forms and Alluvial Roughness"

The pioneering predictor of fluvial bed-load transport rate proposed by Meyer-Peter and Muller in 1948 is still extensively used in basic research and engineering applications. A review of the basis for its formulation reveals, however, that an unnecessary bed roughness correction was applied to cases of plane-bed morphodynamic equilibrium. Its inclusion followed a flow resistance parameterization in terms of the Nikuradse roughness height, which has been shown (well after the publication of their work) to be inappropriate for the characterization of mobile bed rough conditions in rivers. Removing the unnecessary correction and incorporating an improved correction of the boundary shear stress due to sidewall effects allow elucidation of the most parsimonious form of the bed-load relation of Meyer-Peter and Muller that is dictated by their own data set. The new predictor is presented in terms of two alternative power law forms. These amended forms show that, in the case of lower-regime plane-bed equilibrium transport of uniform bed sediment, the new estimates of volume bed-load transport rates are less than or equal to half the values that would be obtained with the original relation of Meyer-Peter and Muller in the absence of the unnecessary bed roughness correction. The meticulous database and clear analysis of the original work of Meyer-Peter and Muller greatly aided the present writers in their reanalysis, which liberally uses the hindsight offered by 58 years of subsequent research.

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Reanalysis and Correction of Bed-Load Relation of Meyer-Peter and Müller Using Their Own Database

Experimental research has been performed to determine the sediment pick-up by a uniform flow without initial sediment load. A sediment lift was designed by which the sediment particles were moved upwards at a constant rate through a circular opening in the flume bottom. Five types of bed material (sand) have been used with D\d5\d0-values in the range 130-1500μm. The mean flow velocities were in the range 9.5-1.0 m/s. The experimental results have been used to derive an empirical pick-up function. The results have also been used to evaluate several existing pick-up functions. Finally, the proposed empirical pick-up function has been applied to predict the bed-load and suspended load transport. In the latter application the proposed function has been used as a bed-boundary condition in a mathematical model for suspended sediment transport.

Sediment Pick‐Up Functions

The eguivalent roughness of a movable bed is considered. Relationships are given which can be used to determine the equivalent bed roughness from the bed material size and the bed-form dimensions. In the case of a plane bed the equivalent roughness is related to the D 9 0 of the bed material. Based on flume and field data, the equivalent roughness may vary from 1-10 D 9 0 . Similar values were reported by other research-workers. In the case of bed forms the equivalent roughness is related to the average height and length of the bed forms. Both flume and field data were used to determine a functional relationship. The proposed relationship yields values which are considerably smaller than other existing relationships.

C Leo

Papers

Sediment transport; Part I, Bed load transport

Sediment Transport, Part III: Bed Forms and Alluvial Roughness

Closure of "Sediment Transport, Part III: Bed Forms and Alluvial Roughness"

Sediment Pick‐Up Functions

Equivalent Roughness of Alluvial Bed