Three-dimensional modeling of tsunami waves with rigid vegetation.

Maria Maza, Javier L. Lara, Inigo J. Losada

Wednesday 1 july 2015

8:45 - 9:00h at Amazon (level 1)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 8C. Coastal Engineering

Last years tsunami events have pointed out the necessity of searching for new ways of coastal protection against coastal erosion and flooding. Different authors have reported the coastal protection by mangrove forest. Human and economic damage reduction has been reported at dense mangrove forests locations in comparison with bare sand areas (e.g. Tanaka et al., 2007; Vo-Luong and Massel, 2008). This study presents a three-dimensional CFD numerical analysis of the interaction of tsunami waves with mangrove forest. The IHFOAM model (Higuera et al., 2013) is used to determine tsunami wave damping by rigid vegetation and wave-exerted forces in the vegetation field. Tsunami waves are reproduced considering solitary waves. The mangrove forest is represented using emergent rigid cylinders. The study presents a first approach based on a macroscopic modeling of the flow within the cylinders field considering a drag force to model the momentum damping. Considering the exact geometry of the cylinders field in the model motivates the second approach. The model is validated using laboratory data. The ability and the suitability of the use of both approaches are discussed showing their capacity in determining the wave height evolution along the field and the forces exerted in the cylinders. The second approach allows studying flow characteristics around each individual cylinder and new features, such as the influence of the cylinders spatial distribution in wave damping, are studied.