Field Observations of Wave-Induced Streaming through a Submerged Seagrass (Posidonia Oceanica) Meadow
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Author(s)
Orfila, Alejandro
Terrados, Jorge
Luhar, Mitul
Infantes Oanes, Eduardo
Nepf, Heidi
Date Issued
March 2013
Journal
Journal of Geophysical Research: Oceans
Publisher
American Geophysical Union (AGU)
Citation
Luhar, Mitul et al “Field Observations of Wave-Induced Streaming through a Submerged Seagrass (Posidonia Oceanica) Meadow.” Journal of Geophysical Research: Oceans 118, 4 (April 2013): 1955–1968 © 2013 American Geophysical Union
Version
Final published version
Abstract
This paper reports the findings of a 2 week field campaign designed to study wave-induced flows within a meadow of Posidonia oceanica at water depth 9 m. Previous laboratory experiments suggest that waves induce a mean mass drift in the direction of wave propagation ("streaming") through submerged canopies of vegetation. This paper provides the first field measurements of this wave-induced streaming. During periods of high wave activity, streaming flows with magnitudes as high as 20% of the near-bed oscillatory velocity were measured within the meadow. In addition to presenting field measurements of wave-induced streaming, this paper also considers the damping of wave-induced oscillatory flow within the seagrass meadow. Oscillatory velocities measured within the meadow were reduced by less than 30% relative to those above the meadow over the duration of the study. This is in agreement with previous laboratory and field measurements which show that oscillatory flows are damped less within submerged canopies compared to unidirectional flows. Existing analytical models underpredict the magnitude of the streaming flow and overpredict oscillatory velocity reductions. These discrepancies are thought to arise because the drag generated by flexible seagrasses moving with wave-induced flow is not well described. Key Points We present field measurements of wave-induced flow through a seagrass meadow A mean current in the direction of wave propagation is generated within meadow Wave-induced oscillatory velocities are reduced by less than 30% within meadow. Keywords: seagrass; vegetated flow; canopy flow; streaming; wave-induced current; oscillatory flow reduction
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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DOI of Published Version
https://doi.org/10.1002/JGRC.20162
