Rip channels, megacusps, and shoreline change: measurements and modeling

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dc.contributor.advisorThornton, Edward B.
dc.contributor.authorOrzech, Mark D.
dc.contributor.departmentOceanography (OC)
dc.dateJune 2010
dc.date.accessioned2012-08-22T15:32:40Z
dc.date.available2012-08-22T15:32:40Z
dc.date.issued2010-06
dc.description.abstractTo investigate the relationship between alongshore rip channel migration rates and alongshore sediment transport rates, multi-year surf-zone video and wave datasets are examined at three sites along Monterey Bay, on the coast of California. Time-averaged, rectified video images are used to estimate daily rip migration rates, and the CERC formula is used to compute concurrent bulk alongshore sediment transport rates. Correlation coefficients between daily rates of transport and migration are low, but they improve with frequency-based filtering. While higher frequency migration events (on time scales shorter than eight days) are often obscured below the "noise floor," longer period oscillations (spring/neap tidal and seasonal cycles) show up more clearly. Cumulatively summed mean rip migration distance and net alongshore sediment transport correlate well (with correlation coefficient r = 0.76 - 0.94), indicating that an approximately linear relationship exists at longer timescales. To examine the nature of megacusp formation on rip channel bathymetries and identify dominant sediment transport components, five years of surf-zone video and ADCP wave data are analyzed and the XBeach 2DH nearshore model is applied in a series of simulations over realistic bathymetries. XBeach is shown to hindcast measured shoreline change with moderate skill for lower wave energies. A process-based analysis is used to identify significant forcing terms at mean, infragravity, and very-low-frequency timescales. Observations and model results both suggest that megacusps can form shoreward of either rip channels or shoals, depending on forcing conditions. In all model simulations, mean advective sediment transport plays the most important role in the creation of megacusps.en_US
dc.description.urihttp://archive.org/details/ripchannelsmegac1094510532
dc.format.extentxxii, 109 p. : ill. maps. ; 28 cm.en_US
dc.identifier.urihttps://hdl.handle.net/10945/10532
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.en_US
dc.subject.authorRip channelsen_US
dc.subject.authormegacuspsen_US
dc.subject.authoralongshore sediment transporten_US
dc.subject.authormorphodynamicsen_US
dc.subject.authorXBeachen_US
dc.subject.authorsurf-zone videoen_US
dc.subject.authorcorrelationsen_US
dc.subject.authorinfragravityen_US
dc.subject.authorVLFen_US
dc.subject.lcshMeasurement.en_US
dc.titleRip channels, megacusps, and shoreline change: measurements and modelingen_US
dc.typeThesisen_US
dspace.entity.typePublication
etd.thesisdegree.disciplinePhysical Oceanographyen_US
etd.thesisdegree.grantorNaval Postgraduate Schoolen_US
etd.thesisdegree.levelDoctoralen_US
etd.thesisdegree.nameDoctor Of Philosophy in Physical Oceanographyen_US
relation.isDepartmentOfPublication26f8a402-a71f-4404-879b-8121771ae440
relation.isDepartmentOfPublication.latestForDiscovery26f8a402-a71f-4404-879b-8121771ae440
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