Generation of Nearshore Bars by Multi-Domain Hybrid Numerical Model

Abstract

A multi-domain hybrid numerical model for the prediction of cross-shore sediment transport including bar generation and movement is developed in this paper based on the macro-scale sediment transport rate and conservation equations. The surf zone is divided into several sub-domains, such as numerical post-breaking zone and analytical breaking and pre-breaking zones. Different empirical sediment transport rate equations are defined in each region. In the post-breaking zone, an inhomogeneous diffusion equation is solved with moving boundary conditions. The solutions in each domain are matched at the patching boundaries by the continuity of the beach profile and sediment transport rate. It is verified that the present hybrid numerical model reasonably simulates beach erosion, dune recession, and bar formation and movement. The model conserves the overall sediment volume and converges toward a steady-state solution. The model is also validated through comparison with laboratory and field data. The numerical model can straight-forwardly be extended to generate multiple bars. Using the developed program, it is shown that the bar formation can be greatly influenced by the pattern of the storm surge hydrograph.