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New Implementation in SWAN for Quantifying Wave Attenuation by Vegetation

Author(s): Fernando Lopez Arias; Maria Maza; Javier L. Lara; Inigo J. Losada

Linked Author(s): Maria Maza

Keywords: Saltmarshes; Standing biomass; Wave height attenuation; SWAN; Predictive tool

Abstract: Intertidal vegetation, such as mangroves and saltmarshes, plays an important role in coastal protection service due to its ability to reduce the energy from waves. In last years, numerical models have been developed to reproduce the wave height decay along these ecosystems modeling the energy damping. Currently, the third-generation full-spectrum model SWAN (Simulating Waves Nearshore) is widely used to quantify wave height attenuation along coastal vegetation fields. This model is based on the definition of the vegetation field using parameters such as vegetation height, stem diameter and density, and a bulk drag coefficient obtained by empirical formulations, calibration methods or direct force measurements that are case-specific. A new formulation based on vegetation standing biomass has been considered to overcome these limitations. Thus, this work shows the implementation of this formula in SWAN and the validation carried out using laboratory and field data. The new implementation adequately reproduces the wave height decay observed along different saltmarsh species tested in the laboratory under different hydrodynamic conditions. Additionally, the implemented model is validated by using field measurements taken at two different locations where different species were present. Hence, the model is validated for six different saltmarsh species. This new implementation in SWAN represents a new predictive tool capable of obtaining the wave height decay produced by saltmarshes without the need for model calibration.


Year: 2022

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