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A comparison between fluid shear stress reduction by halophytic plants in Venice Lagoon, Italy and Rustico Bay, Canada - analyses of in situ measurements

A comparison between fluid shear stress reduction by halophytic plants in Venice Lagoon, Italy and Rustico Bay, Canada - analyses of in situ measurements
A comparison between fluid shear stress reduction by halophytic plants in Venice Lagoon, Italy and Rustico Bay, Canada - analyses of in situ measurements
A series of in situ experiments on bed stability were carried out at three sites across Venice Lagoon using the benthic annular flume—Sea Carousel. Turbulence measurements were made at a range of flow speeds over different vegetated beds as well as ‘smooth’ muddy beds. The drag induced by the various bed types was estimated using flow deceleration. Bed shear stress was also estimated using three methods, and the results were compared with the bed shear stress as determined over a smooth bed in a laboratory equivalent of Sea Carousel—Lab Carousel. The stress was found to increase with increasing bed roughness and with the addition of vegetation in the form of the sea grasses Cymodocea nodosa and Zostera noltii. The stress was also found to be affected by the bending of the sea grass blades under flow velocities exceeding 0.4 m s?1, the sea grasses became flattened and the shear stress was found to decrease to produce skimming flow. It was concluded that the presence of sea grasses decreases erosion due to (1) stress reduction and (2) stabilization of the bed, thus reduction of the distribution of sea grass beds in Venice Lagoon will likely enhance bed erosion and hence habitat destruction. Stress was also reduced by an increase in levels of turbidity level in the water column.
stress, sea grass, bed
0924-7963
293-308
Thompson, C.E.L.
2a304aa6-761e-4d99-b227-cedb67129bfb
Amos, C.L.
d0a18a13-bccd-4fdc-8901-aea595d4ed5c
Umgiesser, G.
715016aa-c166-4598-89fc-cf2af5a85c78
Thompson, C.E.L.
2a304aa6-761e-4d99-b227-cedb67129bfb
Amos, C.L.
d0a18a13-bccd-4fdc-8901-aea595d4ed5c
Umgiesser, G.
715016aa-c166-4598-89fc-cf2af5a85c78

Thompson, C.E.L., Amos, C.L. and Umgiesser, G. (2004) A comparison between fluid shear stress reduction by halophytic plants in Venice Lagoon, Italy and Rustico Bay, Canada - analyses of in situ measurements. Journal of Marine Systems, 51 (1-4), 293-308. (doi:10.1016/j.jmarsys.2004.05.017).

Record type: Article

Abstract

A series of in situ experiments on bed stability were carried out at three sites across Venice Lagoon using the benthic annular flume—Sea Carousel. Turbulence measurements were made at a range of flow speeds over different vegetated beds as well as ‘smooth’ muddy beds. The drag induced by the various bed types was estimated using flow deceleration. Bed shear stress was also estimated using three methods, and the results were compared with the bed shear stress as determined over a smooth bed in a laboratory equivalent of Sea Carousel—Lab Carousel. The stress was found to increase with increasing bed roughness and with the addition of vegetation in the form of the sea grasses Cymodocea nodosa and Zostera noltii. The stress was also found to be affected by the bending of the sea grass blades under flow velocities exceeding 0.4 m s?1, the sea grasses became flattened and the shear stress was found to decrease to produce skimming flow. It was concluded that the presence of sea grasses decreases erosion due to (1) stress reduction and (2) stabilization of the bed, thus reduction of the distribution of sea grass beds in Venice Lagoon will likely enhance bed erosion and hence habitat destruction. Stress was also reduced by an increase in levels of turbidity level in the water column.

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More information

Published date: 2004
Keywords: stress, sea grass, bed

Identifiers

Local EPrints ID: 28703
URI: http://eprints.soton.ac.uk/id/eprint/28703
ISSN: 0924-7963
PURE UUID: 256b634b-bfd7-4939-97a9-61219152ec56
ORCID for C.E.L. Thompson: ORCID iD orcid.org/0000-0003-1105-6838

Catalogue record

Date deposited: 04 May 2006
Last modified: 16 Mar 2024 03:14

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Author: C.E.L. Thompson ORCID iD
Author: C.L. Amos
Author: G. Umgiesser

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