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WAVE-CURRENT INTERACTIONS AND THEIR EFFECT ON SEDIMENT SUSPENSION WITHIN A ZOSTERA MARINA SEAGRASS BED

Wave motion can interact with the sea floor in shallow coastal areas, including many regions dominated by submerged aquatic vegetation. In combined wave-current flow, bed shear stress is governed by wave boundary layer dynamics adjacent to the sediment-water interface. Stresses exceeding a critical shear stress can locally suspend sediment, attenuating light necessary for the survival of aquatic plants. Within a shallow Virginia coastal bay vegetated by the seagrass Zostera marina, high resolution velocity profiles were collected using acoustic Doppler profilers, while wave attenuation across the 2-km long seagrass bed were quantified using pressure sensors. Turbulence structure and stress distributions due to both waves and currents were quantified after a wave-turbulence decomposition was performed and compared to an unvegetated site to assess the influence of seagrass on boundary layer processes. Reduced wave activity and shear stress within the seagrass bed correlated to reductions in sediment suspension as compared to the unvegetated site, and seagrasses were found to reduce wave heights by up to 50%. However, wave reductions were dependent upon season.

Author

Reidenbach, M. A., University of Virginia, USA, reidenbach@virginia.edu

Details

Oral presentation

Session #:092
Date: 03/02/2017
Time: 15:00
Location: 323 C

Presentation is given by student: No