Computational Modelling of Fluvial Flat Bed Regime

Abstract

This work presents detailed morphodynamics modelling of the bedform under variable discharges and simulates the conditions in which the bed of the river is flattened out in upper plane bed regime. This scenario is simulated by detailed hydrodynamics, sediment transport and morphodynamics models, which is an extension for the model developed by Nabi 1) . Several discharge hydrographs are examined here. In the first case, the discharge increase linearly, and then stay constant. We found that dunes are generated before the condition reaches the upper plane bed regime. As the flow condition fall in the upper plane bed regime, high frequency ripples generate and they flattened the bed out. As the discharge stay constant, the bed remains smooth with small high frequency ripples. Later, four different scenarios are simulated, in which the discharge decreases again after a certain period. It is observed that the bed regenerates again in the case the discharge decreases. The model shows its capability in simulating the flood wave events.