Wave Transformation Through Mangrove Coasts

A Model Study with XBeach-Surfbeat

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Coastal defense mechanisms are an integral part in the safety of infrastructure and communities residing on coastlines around the globe. In long temporal and spatial scales, traditional “hard structures” for coastal defense can become infeasible. Incorporation of soft engineering methods for coastal defense can then be a viable solution. Vegetation belts along the coasts can be a prominent soft engineering application.
Many previous studies have been done to identify the protection offered by coastal vegetation. This thesis aims to identify mangrove vegetation interactions under hazardous wave conditions. Moreover, the study includes a comprehensive parameter space by accommodating the variation in wave climate, vegetation and bathymetry observed in the field.
The hydrodynamic-mangrove interactions are analyzed from the perspective of coastal hazard mitigation by vegetation. The study focuses on wave attenuation, setup variation and runup reduction by mangroves.
The investigations are carried out using a numerical modeling scheme, XBeach-Surfbeat.
Mangrove vegetation can substantially mitigate the effects of coastal hazards by waves (wave energy, wave induced flooding) faced in the hinterland. However, the level of mitigation depends on several factors. The most important factors are, vegetation density, mangrove forest width, wave height and water level.
Denser mangrove vegetation and wider forests increases the wave attenuation while deeper water depths in mangrove forests reduces the attenuation capacity.
The improved understanding of the hydrodynamic-vegetation interactions gained in this study can be used as a foundation for a Bayesian network. A better understanding of the effect of the different parameters on flood mitigation can then be attained.