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Tidal mass exchange between a submersed aquatic vegetation bed and the main channel of the Potomac River

By:
, , ,
Edited by:
Shane Richard M.

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Abstract

Tidal mass exchange between a submersed aquatic vegetation (SAV) bed and the main channel of the Potomac River was investigated. Water levels were recorded at 5 minute intervals from August (when plants were present) through December (when plants were absent). Velocities were measured during individual tidal cycles both in the presence and absence of plants. Flow patterns were found to be altered significantly when plants were present. SAV impeded flow onto the shoal causing a water level phase lag between the bed and the channel, a reduction in flow speed and a change in flow direction. The phase lag was enhanced when the low frequency (subtidal) water level in the channel was below normal. The phase lag was further enhanced during spring tides. Ebb flow in the presence of plants was perpendicular to the edge of the SAV bed in the direction of the pressure gradient established by the lagging water level. Flood flow did not follow such a predictable pattern despite the strongest pressure gradients occurring during flood tides. In the absence of plants the flow speed increased by nearly an order of magnitude and the water-level phase lag disappeared.

Additional Publication Details

Publication type:
Conference Paper
Publication Subtype:
Conference Paper
Title:
Tidal mass exchange between a submersed aquatic vegetation bed and the main channel of the Potomac River
ISBN:
0872628167
Year Published:
1991
Language:
English
Publisher:
Publ by ASCE
Publisher location:
New York, NY, United States
First page:
298
Last page:
304
Number of Pages:
7
Conference Title:
Proceedings of the 1991 National Conference on Hydraulic Engineering
Conference Location:
Nashville, TN, USA
Conference Date:
29 July 1991 through 2 August 1991