QUASI-2-DIMENSIONAL SIMULATION OF SCOUR AND DEPOSITION IN ALLUVIAL CHANNELS

Most existing sediment routing models are one-dimensional models and h ence they cannot be used Co simulate lateral channel bed deformations. Conversely, a two-dimensional model is computationally time consuming , and is not suitable for long-term simulation. Using the stream tube concept, a one-dimensional model is extended to a quasi-two-dimensiona l model in this study. It is capable of simulating lateral variations of channel cross section through the adjustments of stream tube bounda ries. The model has an option to treat the suspended load and bed load separately and hence is able to simulate the deposition behavior of t he suspended sediment under a nonequilibrium process. The model also p rovides options to solve either de Saint Venant equation or energy equ ation and hence can be applied in both steady and unsteady flow condit ions. An assessment of this model's performance has been conducted thr ough a comparison to an analytical solution and a set of experimental data, The application of this model to the Keelung River and the Shiem en Reservoir in Taiwan also gave convincing results.