Thesis
Wave dissipation through flexible salt marsh vegetation
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/101999
Abstract
Measurement of waves propagating through an emergent vegetated canopy were used to test models for dissipation by rigid or flexible vegetation. A transect of 3 pulse-coherent Acoustic Doppler Current Profilers (ADCPs) extending 46 m into a natural salt marsh recorded velocity, at 8 Hz every 0.04 m along vertical profiles extending 0.07 - 0.27 m above the bed, and pressure. Stem lengths, basal diameters and densities were 0.03 - 1.36 m, 3.4 - 8.5 mm and 264 - 1168 stems/m2 respectively. Water depths varied tidally from 0 to 1.1 m. Most (56 - 81%) of the wave energy was dissipated within 19 m of the marsh edge. Two wave dissipation models, the first assuming rigid vegetation, and the second simulating wave-forced vegetation motion, were tested against the observed dissipation. Both models yielded a good fit to the observed dissipation (skill score = 0.95 - 0.99). However, best fit drag coefficients for the rigid model (0.58 - 0.78) were below the range (1.2 - 2.5) expected for the observed Reynolds numbers, whereas drag coefficients for the flexible model (0.97 - 1.57) were nearer the expected range. These results suggest that vegetation motion reduced wave dissipation, thus indicating the importance of including vegetation motion for accurate wave dissipation predictions.
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Details
- Title
- Wave dissipation through flexible salt marsh vegetation
- Creators
- Kassondera Celest Dallavis
- Contributors
- Stephen M. Henderson (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525144601842
- Language
- English
- Resource Type
- Thesis