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Wave energy and wave-induced flow reduction by full-scale model Posidonia oceanica seagrass

Wave energy and wave-induced flow reduction by full-scale model Posidonia oceanica seagrass
Wave energy and wave-induced flow reduction by full-scale model Posidonia oceanica seagrass
This paper presents results from experiments in a large flume on wave and flow attenuation by a full-scale artificial Posidonia oceanica seagrass meadow in shallow water. Wave height and in-canopy wave-induced flows were reduced by the meadow under all tested regular and irregular wave conditions, and were affected by seagrass density, submergence and distance from the leading edge. The energy of irregular waves was reduced at all components of the spectra, but reduction was greater at the peak spectral frequency. Energy dissipation factors were largest for waves with small orbital amplitudes and at low wave Reynolds numbers. An empirical model, commonly applied to predict friction factors by rough beds, proved applicable to the Posidonia oceanica bed. However at the lowest Reynolds numbers, under irregular waves, the data deviated significantly from the model. In addition, the wave-induced flow dissipation in the lower canopy increased with increasing wave orbital amplitude and increasing density of the mimics. The analysis of the wave-induced flow spectra confirm this trend: the reduction of flow was greatest at the longer period component of the spectra. Finally, we discuss the implications of these findings for sediment dynamics and the role of Posidonia oceanica beds in protecting the shore from erosion.
Posidonia oceanica, Seagrass, Wave-induced flow, Energy dissipation factor, Wave-vegetation interactions
0278-4343
100-116
Manca, E.
b18a8474-73fc-47b3-8ec3-c4a94af8e402
Caceres, I.
bd1d8f9f-0028-4c1e-9ee5-c67e8fd132b0
Alsina, J.
d0e42f0b-fdc3-46af-b56b-b45b271db388
Stratigaki, V.
8f289096-ef82-4afc-be75-7779ac67f52c
Townend, I.
ffb3f596-04b2-4eee-a871-e285cdc85a4c
Amos, C.L.
d0a18a13-bccd-4fdc-8901-aea595d4ed5c
Manca, E.
b18a8474-73fc-47b3-8ec3-c4a94af8e402
Caceres, I.
bd1d8f9f-0028-4c1e-9ee5-c67e8fd132b0
Alsina, J.
d0e42f0b-fdc3-46af-b56b-b45b271db388
Stratigaki, V.
8f289096-ef82-4afc-be75-7779ac67f52c
Townend, I.
ffb3f596-04b2-4eee-a871-e285cdc85a4c
Amos, C.L.
d0a18a13-bccd-4fdc-8901-aea595d4ed5c

Manca, E., Caceres, I., Alsina, J., Stratigaki, V., Townend, I. and Amos, C.L. (2012) Wave energy and wave-induced flow reduction by full-scale model Posidonia oceanica seagrass. Continental Shelf Research, 50-51, 100-116. (doi:10.1016/j.csr.2012.10.008).

Record type: Article

Abstract

This paper presents results from experiments in a large flume on wave and flow attenuation by a full-scale artificial Posidonia oceanica seagrass meadow in shallow water. Wave height and in-canopy wave-induced flows were reduced by the meadow under all tested regular and irregular wave conditions, and were affected by seagrass density, submergence and distance from the leading edge. The energy of irregular waves was reduced at all components of the spectra, but reduction was greater at the peak spectral frequency. Energy dissipation factors were largest for waves with small orbital amplitudes and at low wave Reynolds numbers. An empirical model, commonly applied to predict friction factors by rough beds, proved applicable to the Posidonia oceanica bed. However at the lowest Reynolds numbers, under irregular waves, the data deviated significantly from the model. In addition, the wave-induced flow dissipation in the lower canopy increased with increasing wave orbital amplitude and increasing density of the mimics. The analysis of the wave-induced flow spectra confirm this trend: the reduction of flow was greatest at the longer period component of the spectra. Finally, we discuss the implications of these findings for sediment dynamics and the role of Posidonia oceanica beds in protecting the shore from erosion.

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More information

e-pub ahead of print date: 29 October 2012
Published date: 15 December 2012
Keywords: Posidonia oceanica, Seagrass, Wave-induced flow, Energy dissipation factor, Wave-vegetation interactions
Organisations: Coastal & Shelf Research

Identifiers

Local EPrints ID: 344771
URI: http://eprints.soton.ac.uk/id/eprint/344771
ISSN: 0278-4343
PURE UUID: 60509817-f83b-4a93-b29e-a0fd8be1ac15

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Date deposited: 31 Oct 2012 09:28
Last modified: 14 Mar 2024 12:18

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Contributors

Author: E. Manca
Author: I. Caceres
Author: J. Alsina
Author: V. Stratigaki
Author: I. Townend
Author: C.L. Amos

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