| Title | Modelling seabed disturbance and sediment mobility on the Canadian Atlantic Shelf |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Li, M Z ; Wu, Y;
Hannah, C G; Perrie, W A; Shen, H; King, E L |
| Source | Geological Survey of Canada, Open File 8805, 2021, 50 pages, https://doi.org/10.4095/328363  Open Access |
| Image |  |
| Year | 2021 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Eastern offshore region; Northern offshore region; Newfoundland and Labrador; Nova Scotia; Prince Edward Island; New Brunswick; Nunavut; Quebec; British Columbia; Alberta; Saskatchewan; Manitoba;
Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut; Canada |
| NTS | 1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 24; 25; 26; 27; 28; 29; 37; 38; 39; 120 |
| Area | Atlantic Ocean; Hudson Strait; Gulf of St. Lawrence; Davis Strait; Labrador Sea; Baffin Bay; Nares Strait; Bay of Fundy; Scotian Shelf; The Grand Banks of Newfoundland; Canada; Greenland; Denmark |
| Lat/Long WENS | -80.0000 -42.0000 84.0000 39.0000 |
| Subjects | marine geology; surficial geology/geomorphology; sedimentology; environmental geology; Nature and Environment; Science and Technology; marine sediments; marine environments; continental margins;
continental shelf; oceanography; currents; current circulation; storms; sediment stability; sediment distribution; sediment dispersal; sediment transport; grain size analyses; shear stress; stress analyses; bathymetry; benthos; modelling; models;
statistical analyses; Atlantic Continental Shelf; Seabed Disturbance Index (SDI); Sediment Mobility Index (SMI); Habitats; Land management; Methodology; Classification |
| Illustrations | geoscientific sketch maps; location maps; tables |
| Program | Marine Geoscience for Marine Spatial Planning |
| Released | 2021 06 08 |
| Abstract | (Summary)
Ocean surface waves and tidal currents can interact to produce strong seabed shear stress and mobilization of sediments that can significantly impact the seabed stability and benthic
habitats on continental shelves. Therefore the knowledge of the magnitude and frequency of seabed disturbance by waves and currents and the resulting mobilisation of sediment on continental shelves is critical for the spatial planning and management
of Canada's offshore lands. Modelled waves, tidal current and circulation current data for a 3-year period were used in a combined-flow sediment transport model to simulate the seabed shear stresses and the mobilization of observed sediment grain
size on the Canadian Atlantic Shelf. The modelling results are presented and analyzed to derive updated framework of seabed disturbance and sediment mobility on the Atlantic Shelf.
The Atlantic Shelf is affected by strong waves and tidal currents.
Maximum mean significant wave height can reach 3.5 m and that of the mean tidal currents up to 1.2 m·s-1. Our modeled results indicate that the mean wave and tidal current shear velocities both reach the maximum values of ~4 cm·s-1. Our models
predict that observed sediments on the Atlantic Shelf can be mobilized by tidal currents at least once during the modelled 3 year period over 30% of the shelf area while storms can mobilize sediments over 35% of the shelf area suggesting slightly
stronger sediment mobilization by storms. Further more waves and currents interact to cause enhanced combined wave-current shear velocity >5 cm·s-1 that is capable to mobilize sediments over 63% of the shelf area, double that due to either tides or
waves.
The spatial variation of the relative importance of waves, tidal current and circulation current in mobilizing sediments was used to classify the Atlantic Shelf into six disturbance types. Wave dominant and tide dominant disturbance types
are equally important and both occupy ~25% of the shelf area. Mixed disturbance is insignificant and accounts for only 3% of the shelf area. Universal indices of Seabed Disturbance (SDI) and Sediment Mobility (SMI) were applied to better quantify the
exposure of the seabed to oceanographic processes and sediment mobility incorporating both the magnitude and frequency of these processes. The applications of these indices have produced different and probably more adequate quantification of seabed
forcing and sediment mobility for many areas on the Atlantic Shelf. The values of SDI and SMI on the Canadian Atlantic Shelf are found to be comparable to those on the Australian shelf. These indices, together with the seabed disturbance type
classification scheme, potentially can be used as standard parameters to best quantify seabed disturbance and sediment mobility on other shelves of the world. |
| Summary | (Plain Language Summary, not published)
Modelling Seabed Disturbance and Sediment Mobility on the Canadian Atlantic Shelf Modelled waves, tidal current and circulation current for a 3-year
period were used in a sediment transport model to quantify the seabed shear stresses and the mobilization of observed sediment grain size on the Canadian Atlantic Shelf. The study results led to the updated framework of seabed disturbance and
sediment mobility on the Atlantic Shelf. Strong waves and tidal currents produce mean bed shear velocity > 5 cm/s and cause sediment mobilization for >60% of the time over the Atlantic Shelf. The relative importance of waves, tidal current and
circulation current in mobilizing sediments was used to classify the Atlantic Shelf into six disturbance types. The results of the study are important for environmental assessments, planning for seabed infrastructure, and better understanding of
seabed fisheries. |
| GEOSCAN ID | 328363 |
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