| Abstract: | This paper aims to explore the coupling mechanism between flow movement, sediment transport and riverbed evolution in currently widely used mathematical models for sediment transport. Based on characteristic theory, analytic forms of eigenvalues, eigenvectors and characteristic relationships of total-sediment transport model, bed-load transport model and suspened- load transport model were derived, respectively. The singular perturbation technology was implemented to obtain the asymptotic solutions to different families of eigenvalues. The results indicate that, interactions between motion variables were explicitly coupled in the characteristics of total-sediment transport model and bed-load transport model. Further qualitative and quantitative analysis demonstrates that high sediment transport intensity and significant riverbed change will inevitably affect the property of flow movement. In the process of deposition, sediment-laden flow will move faster when sediment transport intensity becomes stronger. In contrast, the wave of flow will propagate at slower speed as erosion intensity becomes stronger. For most existing suspended-load transport models, however, the characteristics are decoupled as the interactions between motion variables cannot be integrally illustrated in eigenvalues, eigenvectors and characteristic relationship. |
