A Depth-averaged 2-d Simulation for Coastal Barrier Breaching Processes

A depth-averaged 2-D model has been developed for simulating coastal barrier breaching processes. The model solves the generalized shallow water equations and the non-equilibrium sediment transport and bed change equations in a coupled fashion using an explicit finite volume method on a rectangular grid. It considers interactions among transient flow, strong sediment transport, and rapid bed change by including bed change and variable flow density in the flow continuity and momentum equations. The model adopts the HLL approximate Riemann solver to handle the mixed-regime flows near the breach and the wetting-drying problem. The developed model has been tested against a lab experiment of dike-break flow over movable bed and a field experiment of sea dike breaching. The simulation results demonstrate that the model is capable of calculating the initial development stage of coastal barrier breaching under supercritical flow. Future work will improve the model to include waves for more general application in the coastal context.