Tidal sedimentology and geomorphology in the central Salish Sea straits, British Columbia and Washington State

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dc.contributor.author Mullan, Sean
dc.date.accessioned 2018-01-03T20:02:10Z
dc.date.copyright 2017 en_US
dc.date.issued 2018-01-03
dc.identifier.uri http://hdl.handle.net/1828/8943
dc.description.abstract Intra-archipelago waterways, including tidal strait networks, present a complex set of barriers to, and conduits for sediment transport between marine basins. Tidal straits may also be the least well understood tide-dominated sedimentary environment. To address these issues, currents, sediment transport pathways, and seabed sedimentology & geomorphology were studied in the central Salish Sea (Gulf and San Juan Islands region) of British Columbia, Canada and Washington State, USA. A variety of data types were integrated: 3D & 2D tidal models, multibeam bathymetry & backscatter, seabed video, grab samples, cores and seismic reflection. This dissertation included the first regional sediment transport modelling study of the central Salish Sea. Lagrangian particle dispersal simulations were driven by 2D tidal hydrodynamics (~59-days). It was found that flood-tide dominance through narrow intra-archipelago connecting straits resulted in the transfer of sediment into the inland Strait of Georgia, an apparent sediment sink. The formative/maintenance processes at a variety of seabed landforms, including a banner bank with giant dunes, were explained with modelled tides and sediment transport. Deglacial history and modern lateral sedimentological and morphological transitions were also considered. Based on this modern environment, adjustments to the tidal strait facies model were identified. In addition, erosion and deposition patterns across the banner bank (dune complex) were monitored with 8-repeat multibeam sonar surveys (~10 years). With these data, spatially variable bathymetric change detection techniques were explored: A) a cell-by-cell probabilistic depth uncertainty-based threshold (t-test); and B) coherent clusters of change pixels identified with the local Moran's Ii spatial autocorrelation statistic. Uncertainty about volumetric change is a considerable challenge in seabed change research, compared to terrestrial studies. Consideration of volumetric change confidence intervals tempers interpretations and communicates metadata. Techniques A & B may both be used to restrict volumetric change calculations in area, to exclude low relative bathymetric change signal areas. en_US
dc.language English eng
dc.language.iso en en_US
dc.rights Available to the World Wide Web en_US
dc.subject tidal strait networks en_US
dc.subject sediment transport pathways en_US
dc.subject seabed sedimentology en_US
dc.subject marine geomorphology en_US
dc.subject Salish Sea en_US
dc.subject Gulf Islands en_US
dc.subject San Juan Islands en_US
dc.subject multibeam bathymetry en_US
dc.subject Lagrangian particle dispersal en_US
dc.subject tidal hydrodynamics en_US
dc.subject Strait of Georgia en_US
dc.subject Strait of Juan de Fuca en_US
dc.subject banner bank en_US
dc.subject giant dunes en_US
dc.subject tidal strait facies model en_US
dc.subject bathymetric change detection en_US
dc.subject t-test en_US
dc.subject local Moran's Ii en_US
dc.subject depth uncertainty en_US
dc.subject volumetric change confidence intervals en_US
dc.subject deglacial history en_US
dc.subject repeat surveys en_US
dc.subject sand dynamics en_US
dc.subject tides en_US
dc.subject sonar en_US
dc.subject marine renewable energy en_US
dc.subject offshore pipelines and cables en_US
dc.subject benthic habitat en_US
dc.subject spatial autocorrelation en_US
dc.subject spatial analysis and statistics en_US
dc.subject geographic information system (GIS) en_US
dc.subject finite element method (FEM) en_US
dc.title Tidal sedimentology and geomorphology in the central Salish Sea straits, British Columbia and Washington State en_US
dc.type Thesis en_US
dc.contributor.supervisor Barrie, James Vaughn
dc.contributor.supervisor Pospelova, Vera
dc.degree.department School of Earth and Ocean Sciences en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.description.scholarlevel Graduate en_US
dc.description.embargo 2018-12-07

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