Item Details

Impacts of Fringing Oysters Reefs on Wave Attenuation and Marsh Erosion Rates

Taube, Sara Reid
Format
Thesis/Dissertation; Online
Author
Taube, Sara Reid
Advisor
Howard, Alan
Wiberg, Patricia
Reidenbach, Matt
McGlathery, Karen
Abstract
Mainland marshes in the Virginia Coast Reserve have been eroding at rates that vary both spatially and temporally. Data from these study sites showed statistically significant upward trends in the rate of shoreline retreat over the course of the last 52 years. This increase in erosion rates corresponds to an increase in the frequency of hurricanes and tropical storms passing within 100 km of the study sites. The correlation between hurricane frequency and erosion rates suggest that these high-energy storms could have been the main cause of rapid marsh-edge erosion. Average erosion rates from this study were similar to those measured by McLoughlin et al. (2011) on other mainland marshes in the Virginia Coast Reserve, as was the spatial variability. Erosion at the study sites was less than the regional erosion rate calculated in Hog Island Bay to be 1.2 m·yr -1 . Oyster reefs were shown to have successfully dissipated wind-wave energy, the primary driver of erosion in the Virginia Coast Reserve, and have the potential to work as an erosion control method. For significant waves, the mean dissipation of wave power was 49%. Attenuation of wave energy was determined by multiple factors, primarily water depth above the reef and significant wave height. An ideal range of depths at which reefs were most effective was identified, above which, additional increases in water depth diminished the interaction. This occurred because although waves continued to grow with greater water depth, the decay in orbital motion with depth was sufficient that the waves were no longer strongly modified by the underlying reef surface. Strategic installment of reefs based on prominent wind direction and fetch in relationship to marsh shorelines is likely key to greater erosion mitigation. Note: Abstract extracted from PDF text
Language
English
Date Received
20140123
Published
University of Virginia, Department of Environmental Sciences, MS (Master of Science), 2013
Published Date
2013-05-01
Degree
MS (Master of Science)
Collection
Libra ETD Repository
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