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Steve Elgar. Hoefel, Fernanda Gemael, 1973- Joint Program in Oceanography/Applied Ocean Science and Engineering. Woods Hole Oceanographic Institution Joint Program in Oceanography/Applied Ocean Science and Engineering Massachusetts Institute of Technology. Department of Ocean Engineering 2005-09-27T17:21:10Z 2005-09-27T17:21:10Z 2004 2004 http://hdl.handle.net/1721.1/28619 57561548 Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2004. Includes bibliographical references. Onshore sediment transport and sandbar migration are important to the morphological evolution of beaches, but are not understood well. Here, a new model that accounts for accelerations of wave-orbital velocities predicts onshore sandbar migration observed on an ocean beach. In both the observations and the model, the location of the maximum acceleration-induced transport moves shoreward with the sandbar, resulting in feedback between waves and morphology that drives the bar shoreward until conditions change. A model that combines the effects of transport by waves and mean currents simulates both onshore and offshore bar migration observed over a 45-day period. A stochastic nonlinear Boussinesq model for the evolution of waves in shallow water is coupled with the wave-acceleration-driven sediment transport model to predict observed onshore sediment transport and sandbar migration given observations of the offshore wave field and initial bathymetry. The Boussinesq-wave model has skill in predicting wave spectra, as well as velocity and acceleration statistics across the surfzone, but it underpredicts acceleration skewness on top of the sandbar. As a result, the coupled wave-sediment transport model underpredicts sediment transport, and thus fails to move the sandbar onshore. Although the coupled wave and sediment model can be tuned to yield skillful predictions of onshore sandbar migration, in general, closer agreement between observed and modeled statistics of the wave field is essential for the successful application of wave models to predict sediment transport. by Fernanda Gemael Hoefel. Ph.D. 61 leaves 3012035 bytes 3017570 bytes application/pdf application/pdf en_US Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Woods Hole Oceanographic Institution. Earth, Atmospheric, and Planetary Sciences. /Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering. Observations and modeling of wave-acceleration-induced sediment transport in the surfzone Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="10729cfd-ec24-4ae2-b923-ea05f8b0668e"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>en_US</Language> <Title>Observations and modeling of wave-acceleration-induced sediment transport in the surfzone</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2004</PublicationDate> <Authors> <Author> <DisplayName>Hoefel, Fernanda Gemael, 1973-</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Woods Hole Oceanographic Institution.</Keyword> <Keyword>Earth, Atmospheric, and Planetary Sciences.</Keyword> <Keyword>/Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering.</Keyword> <Abstract>Onshore sediment transport and sandbar migration are important to the morphological evolution of beaches, but are not understood well. Here, a new model that accounts for accelerations of wave-orbital velocities predicts onshore sandbar migration observed on an ocean beach. In both the observations and the model, the location of the maximum acceleration-induced transport moves shoreward with the sandbar, resulting in feedback between waves and morphology that drives the bar shoreward until conditions change. A model that combines the effects of transport by waves and mean currents simulates both onshore and offshore bar migration observed over a 45-day period. A stochastic nonlinear Boussinesq model for the evolution of waves in shallow water is coupled with the wave-acceleration-driven sediment transport model to predict observed onshore sediment transport and sandbar migration given observations of the offshore wave field and initial bathymetry. The Boussinesq-wave model has skill in predicting wave spectra, as well as velocity and acceleration statistics across the surfzone, but it underpredicts acceleration skewness on top of the sandbar. As a result, the coupled wave-sediment transport model underpredicts sediment transport, and thus fails to move the sandbar onshore. Although the coupled wave and sediment model can be tuned to yield skillful predictions of onshore sandbar migration, in general, closer agreement between observed and modeled statistics of the wave field is essential for the successful application of wave models to predict sediment transport.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>