The effects of wave non-linearity on wave attenuation by vegetation

Phan Khanh, L.; Stive, M.J.F.; Zijlema, M.; Truong, H.T.X.; Aarninkhof, S.G.J.

doi:10.1016/j.coastaleng.2019.01.004

The effects of wave non-linearity on wave attenuation by vegetation

Title

The effects of wave non-linearity on wave attenuation by vegetation

Author

Phan Khanh, L. (TU Delft Coastal Engineering)
Stive, M.J.F. (TU Delft Coastal Engineering)
Zijlema, M. (TU Delft Environmental Fluid Mechanics)
Truong, H.T.X. (TU Delft Structural Integrity & Composites; Thuy Loi University)
Aarninkhof, S.G.J. (TU Delft Coastal Engineering)

Date

2019

Abstract

Wave attenuation through mangrove forests has received more and more attention, especially in the context of increasing coastal erosion and sea-level-rise. Numerous studies have focused on studying the reduction of wave height in a mangrove forest. However, the understanding of this attenuation process is still in its infancy. In order to obtain more insight, a laboratory experiment, mimicking the processes of wave attenuation by coastal mangroves in the Mekong Delta, Vietnam was conducted. The reduction of wave height for different scenarios of mangrove densities and wave conditions was investigated. A new method to quantify vegetation attenuation induced by vegetation is presented. The wave height reduction is presented over a relative length scale (viz. the number of wavelengths), instead of an absolute length scale of the forest (e.g per meter or per 100 m). The effects of wave non-linearity on the wave height attenuation over the mangrove forest were investigated using the Ursell number. It is suggested that the non-linear character of waves has a strong influence on the attenuation of the waves inside the mangrove forest. A numerical model, mimicking the experiment was constructed in SWASH and validated using the experimental data. Finally, the data set was extended through numerical modelling so that a larger ranging relationship between wave attenuation per wave length and the Ursell number could be formulated.

Subject

Numerical model
Physical model
Vegetation
Wave height attenuation
Wave non-linearity

To reference this document use:

http://resolver.tudelft.nl/uuid:db9ebf80-82bb-48b3-a686-0a1ff0be1eca

DOI

https://doi.org/10.1016/j.coastaleng.2019.01.004

ISSN

0378-3839

Source

Coastal Engineering, 147, 63-74

Part of collection

Institutional Repository