Modeling Attenuation of Storm Surge over Deformable Vegetation: Parametric Study
Publication: Journal of Engineering Mechanics
Volume 142, Issue 8
Abstract
This paper presents a parametric study on storm-surge reduction by flexible vegetation in coastal wetlands under idealized prototype conditions. A vegetation-induced flow resistance model that considers flow depth, flow velocity, and vegetation properties has been developed and verified using laboratory data. The model computes the drag resulting from deformable vegetation under both emergent and submerged conditions. Numerical experiments were conducted to reveal the potential of wetlands in reducing storm surge, and to examine the role of the vegetation field in obstructing surge water. Although a constant Manning’s coefficient is used commonly in hydrodynamic models simulating storm surge over coastal wetlands, the current study reveals the extraordinary temporal variation in the Manning’s coefficient. The dynamic Manning’s coefficient felt by the flow is not only a function of vegetation properties, such as stiffness, diameter, vegetation height and population density, but also varies with the water depth and flow velocity. Before vegetation becomes submerged during a storm event, the dynamic Manning’s coefficient increases with a rising water level; once the plants become submerged the coefficient decreases. The dynamic variation is attributed to the interaction between flow conditions and vegetation stiffness. Both the storm dynamics and vegetation biomechanical properties need to be taken into account for the parameterization of vegetation-induced drag and the assessment of flood risk reduction by coastal wetlands.
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Acknowledgments
Funding provided by the National Science Foundation (NSF Grants CCF-1539567 and SEES-1427389) and the Louisiana Sea Grant (LSG) College Program is greatly acknowledged. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the NSF and LSG.
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Information & Authors
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Published In
Journal of Engineering Mechanics
Volume 142 • Issue 8 • August 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Jun 7, 2015
Accepted: Mar 3, 2016
Published online: Apr 22, 2016
Published in print: Aug 1, 2016
Discussion open until: Sep 22, 2016
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