Abstract:
In the aftermath of the Indian Ocean tsunami in 2004 the protection offered by coastal vegetation
became evident in many countries affected and the role of coastal green belts in mitigating tsunami impacts has
now been clearly recognized. Coastal green belts also attract attention as an environmental friendly and cost
effective measure of impact mitigation. In this study, expanding the previous works conducted, further
experiments were conducted to assess the energy dissipation and impact mitigation characteristics of coastal
vegetation in detail. The resistance offered towards the flow which depends on the characteristics of individual
plants and characteristics of the vegetation as a whole were assessed. Tests were conducted in a hydraulic flume
in which vegetation was represented by geometrically similar small scale models. The energy dissipation of
flow through vegetation was determined under steady flow conditions and reduction in inundation extent was
assessed under unsteady flow conditions. Energy dissipation levels up to 48 % and inundation reduction levels
up to 35 % were obtained in the experiments which clearly indicate the effectiveness of coastal green belts in
tsunami impact mitigation. The dependence of the level of inundation reduction on the level of energy
dissipation was also investigated.
