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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