Simulating complex storm surge dynamics: Three‐dimensionality, vegetation effect, and onshore sediment transport

The 3D hydrodynamics of storm surge events, including the effects of vegetation and impact on onshore transport of marine sediment, have important consequences for coastal communities. Here, complex storm surge dynamics during Hurricane Ike are investigated using a three-dimensional (3D), vegetation-resolving storm surge-wave model (CH3D-SWAN) which includes such effects of vegetation as profile drag, skin friction, and production, dissipation, and transport of turbulence. This vegetation-resolving 3D model features a turbulent kinetic energy (TKE) closure model, which uses momentum equations with vegetation induced profile and skin friction drags, a dynamic q2 equation including turbulence production and dissipation by vegetation, as well as vegetation-dependent algebraic length scale equations, and a Smagorinsky type horizontal turbulence model. This vegetation model has been verified using extensive laboratory tests, but this study is a comparison of 2D and 3D simulations of complex storm surge dynamics during Hurricane Ike. We examine the value of 3D storm surge models relative to 2D models for simulating coastal currents, effects of vegetation on surge, and sediment transport during storm events. Comparisons are made between results obtained using simple 2D formulations for bottom friction, the Manning coefficient (MC) approach, and physics-based 3D vegetation-modeling (VM) approach. Lastly, the role that the 3D hydrodynamics on onshore transport and deposition of marine sediments during the storm is investigated. While both the 3D and 2D results simulated the water level dynamics, results of the physics-based 3D VM approach, as compared to the 2D MC approach, more accurately captures the complex storm surge dynamics. This article is protected by copyright. All rights reserved.