Neumeier, U. & Amos, C. L. (2005, in press) Turbulence reduction
by the canopy of coastal Spartina salt-marshes. Journal of Coastal
Research, SI 39 (Proceedings of the 8th International Coastal Symposium),
pg - pg. Itajaí, SC - Brazil.
Abstract
Important features of coastal salt-marshes, that of enhancing sediment accretion
and protecting the shoreline from wave energy, are related to the capacity
of the vegetation to reduce water flow and turbulence. The present study investigates
the poorly understood processes of turbulence attenuation by the canopy.
Wave-dominated turbulence-profiles and turbulence profiles with unidirectional
flow were collected on a Spartina anglica salt-marsh in the Wash (eastern
England). The results showed a significant attenuation of orbital velocities
of waves by the vegetation. Under unidirectional flow, a region of high Reynolds-stress
in the upper part of the canopy separates a zone with reduced turbulence
and limited vertical exchanges in the denser canopy. Both kind of turbulence
reduction favour particle settling and limit vertical exchange in the denser
canopy.
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