SEDIMENT TRANSPORT PROCESSES AND BEDFORM MOBILITY DURING MAJOR STORMS ON GRAND BANKS
Severe winter storms and strong ocean currents create and mobilize various bedforms over the complex sediment texture on the Grand Banks of Newfoundland. Seabed samples and geophysical survey data are used to establish the distribution and morphometrics of major bedforms. Model-predicted wave, tidal, ocean and wind-driven currents for 22 major storms were input in a sediment transport model to predict seabed shear stresses and sediment transport, and to assess mobility of bedforms. The storm impact is mainly determined by wind speed, storm track and storm center translation speed. Maximum significant wave heights reach ~14 m and are generally to the northeast during most major storms. Surface wind-driven currents at the peaks of storms are dominantly to the southeast and reach as high as 140 cm/s; four times stronger than under non-storm conditions. Seabed shear velocity increases from <2 cm/s for non-storm conditions to >10 cm/s during major storms. These cause expansive and significant sediment transport on the Grand Banks. Maximum flux reaches about 2 kg/m/s and occurs on the western and southeastern Grand Banks. Particles as large as small pebbles can be transported and bedforms should be intermittently activated during major storms. Observations of minimal bedform pattern change on the short-term (years) are reconciled with these mobility quantifications.
Li, M. Z., Geological Survey of Canada, Bedford Institute of Oceanography, Dartmouth, NS, B2Y 4A2, Canada, email@example.com
Prescott, R. H., Prescott and Zou Consulting, Halifax, NS, Canada
Wu, Y., Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, NS, Canada
King, E. L., Geological Survey of Canada, Bedford Institute of Oceanography, Dartmouth, NS, Canada
Han, G., Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John’s, NL, Canada
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