Modelling River Bed Form Dynamics: Large Scale Application

This work presents the application of a physically-based morphodynamic model to address the bed form evolution processes in large scale and real-world situation under steady flow as well as moderate flood conditions. Two advanced numerical models were used in this study. Firstly, we examined a fundamental aspect of different sediment transport mechanisms and their effects by using a three-dimensional high-resolution morphodynamic model with an advanced sediment transport modeling approach. The model includes the sliding, pick-up and transport of sediment particles by saltation/suspension. This approach provided a better insight into the physics of sediment transport mechanisms as distinct subsystems and their effects on the bed form morphodynamics. Subsequently, we employed a vertical two-dimensional model with a non-hydrostatic and free-surface flow condition, coupled with equilibrium and non-equilibrium sediment transport approaches. We evaluated and analyzed the relevant issues associated with the effect of different sediment transport approaches on morphodynamic simulation of micro-scale bed forms with a focus on field scale application. We attempted to replicate numerically the bed form evolution in the Chiyoda experimental channel in the Tokachi River (Japan) and field observations in the Waal River (The Netherlands).