Abstract
The paper presents recommendations for using the results obtained in sediment transport simulation and modeling of channel deformations in rivers. This work relates to the issues of empirical modeling of the water flow characteristics in natural riverbeds with a movable bottom (alluvial channels) which are extremely complex. The study shows that in the simulation of sediment transport and calculation of channel deformations in the rivers, it is expedient to use the calculation dependences of Chézy’s coefficient for assessing the roughness of the bottom sediment mixture, or the dependences of the form based on the field investigation data. Three models are most commonly used and based on the original formulas of Meyer-Peter and Müller (1948), Einstein (1950) and van Rijn (1984). This work deals with assessing the hydraulic resistance of the channel and improving the river sediment transport model in a simulation of riverbed transformation on the basis of previous research to verify it based on 296 field measurements on the Central-East European lowland rivers. The performed test calculations show that the modified van Rijn formula gives the best results from all the considered variants.
Highlights
The problem of forecasting channel transformations in riverbeds with a movable bottom is one of the most complex in fluvial hydraulics [1]
The analysis of research published on this work shows that the formula of form (4) has been extensively verified based on the field measurements and laboratory data and is recommended for use in calculations by a number of other authors [9,10,11,12,13,14]. These results indicate the increasing hydraulic resistance when passing from experiments in the trays to the river original flows
The structure of the transport model for non-uniform grain-size sediments test calculations showed that of all the options considered, the best calculation results are obtained based on the original van Rijn formula [24,25], developed by the author for calculating the fine-grained sediment discharge in rivers [31]
Summary
The problem of forecasting channel transformations in riverbeds with a movable bottom (alluvial channels) is one of the most complex in fluvial hydraulics [1]. The task is to perform hydraulic calculations of the water flow characteristics and sediment transport parameters (bottom deformations) in rivers. This boils down to solving by numerical methods a known set of equations of water movement, continuity and deformations at the given initial and boundary conditions. This set of equations in five unknowns is closed by two additional calculation dependences—the hydraulic resistance law in the form of Chézy’s formula and sediment discharge formula. The quality of channel predictions largely depends on reliability of the energy loss estimates over the length and sediment transport parameters in the deformable channel
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