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The AAPG/Datapages Combined Publications Database

GCAGS Transactions


Gulf Coast Association of Geological Societies Transactions
Vol. 24 (1974), Pages 279-282

Effect of Artificial Sea-Grass on Previous HitWaveNext Hit Energy and Near-Shore Sand Transport

Christopher J. Wayne (1)


The emplacement of offshore, artificial sea-grass beds directly influences near-shore sand transport, Artificial sea-grass will decrease Previous HitwaveNext Hit energy due to bending of the fronds, increased bottom drag, internal deformation and refraction. The latter three effects change as a result of the increased bottom slope caused by the sea-grass beds. In turn, the mean longshore current and longshore component of Previous HitwaveNext Hit power are reduced. Total Previous HitwaveNext Hit power and incident angle to the beach specifies the longshore component of Previous HitwaveNext Hit power (PL) which is equated to the quantity of sand moved per unit distance (dq/dx).

The average bending moment per individual frond was calculated to be approximately 2.0 lb.-in. A dense bed of sea-grass has the potential to reduce Previous HitwaveNext Hit energy by twenty percent, based solely on energy lost to bending. The reduction of Previous HitwaveNext Hit height, corresponding to the energy loss, results in decreased Previous HitwaveNext Hit power per unit distance expended at the breaker zone.

Ginsburg and Lowenstam (1957), reported that Thallassia testudinum offers a suitable substrate for many benthic communities. Algae, Foraminifera, bryozoans, etc., attach to the fronds, while mollusks, echinoderms and crustaceans use the network of baffles for protection and food gathering. These organisms add substantially to the binding ability of the grass and sediment will be readily accumulated within the bed. Variations in the type of community present will depend on Previous HitwaveNext Hit energy (turbulence), temperature of the water, tidal range and salinity. In areas of low Previous HitwaveTop energy, embankments may grow, forming a series of offshore bars which will further influence approaching orthogonals.

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