Development of Numerical Model of Unsteady Flow Semi-Coupled with Sediment Transport in River Systems

In recent two decades using the numerical models is common for simulating flow and sediment transport. Numerical models are valuable tools for estimating flow conditions and sediment transport, and are widely applied in water resources management. The main goal of this study is to develop one dimensional, unsteady, hydrodynamic model in which flow and sediment transport can be simulated as semi-coupled in river systems. In this research, the Saint- Venant’s equations are numerically solved for river systems and a semi implicit finite difference scheme is developed to solve the Saint- Venant equations for unsteady flow. The linear equations are produced based on the partial differential equations and the staggered technique. After solving the above equations, the computed hydraulic parameters in this part are sent to the sediment transport segment. The dynamic advection- dispersion equation and the sediment continuity partial differential equation are applied to calculate the suspended sediment and bed load transport rates, respectively. The Exner equation is then used to predict the changes in the river bed elevations. Finally, the model is compared to the Hec-Ras Model and the results show that the developed model has a good accuracy. There are differences in the predicted depth for scour and deposition, which are not unexpected due to differences in the bases of numerical models and between the equilibrium and non-equilibrium conditions of the Exner equation.