Multimode Morphodynamic Model for Sediment-Laden Flows and Geomorphic Impacts

Abstract

Sediment-laden flows are a complex solid-fluid interaction process. This study presents a multimode morphodynamic model system combined with shallow water theory and a nonequilibrium assumption for sediment transport. The model system aims to simulate the morphological change caused by sediment-laden flows with various sediment transport modes. It involves three modules: a hydrodynamic module, a sediment transport module, and a morphological evolution module. The hydrodynamic model is governed by modified shallow water equations considering the interaction effects of flow and sediment. A flexible sediment transport model is presented that incorporates a weight coefficient. The model can adaptively choose an appropriate transport mode according to local, real-time flow conditions. Bedload, suspended load, and total mixed sediment load are all involved. The model is solved by a second-order Godunov-type finite-volume method that is robust and accurate. Validation is demonstrated through a series of test cases. The results indicate that the model can attain good agreement with measured data, thereby demonstrating the capabilities of the multimode morphodynamic model system in predicting sediment-laden flows and resulting morphological change.