Articles | Volume 17, issue 5
https://doi.org/10.5194/nhess-17-693-2017
https://doi.org/10.5194/nhess-17-693-2017
Research article
 | 
16 May 2017
Research article |  | 16 May 2017

Simulations of moving effect of coastal vegetation on tsunami damping

Ching-Piao Tsai, Ying-Chi Chen, Tri Octaviani Sihombing, and Chang Lin

Abstract. A coupled wave–vegetation simulation is presented for the moving effect of the coastal vegetation on tsunami wave height damping. The problem is idealized by solitary wave propagation on a group of emergent cylinders. The numerical model is based on general Reynolds-averaged Navier–Stokes equations with renormalization group turbulent closure model by using volume of fluid technique. The general moving object (GMO) model developed in computational fluid dynamics (CFD) code Flow-3D is applied to simulate the coupled motion of vegetation with wave dynamically. The damping of wave height and the turbulent kinetic energy along moving and stationary cylinders are discussed. The simulated results show that the damping of wave height and the turbulent kinetic energy by the moving cylinders are clearly less than by the stationary cylinders. The result implies that the wave decay by the coastal vegetation may be overestimated if the vegetation was represented as stationary state.

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Short summary
A huge tsunami in Southeast Asia in 2004 has stimulated a debate about the role played by coastal ecosystems in protecting coastal area. Previous approaches assumed that vegetation is stationary and neglected the plant motion with wave. This may lead to overestimation of the effectiveness of coastal vegetation on tsunami damping. We present a coupled wave–vegetation simulation and conclude that the tsunami wave height damping may be overestimated if vegetation motion with wave is neglected.
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