Seabed Disturbance and Bedform Distribution and Mobility on the Storm-Dominated Sable Island Bank, Scotian Shelf

  1. Michael Z. Li2,
  2. Christopher R. Sherwood3 and
  3. Philip R. Hill4
  1. Michael Z. Li,
  2. Edward L. King and
  3. Robert H. Prescott

Published Online: 3 JAN 2013

DOI: 10.1002/9781118311172.ch10

Sediments, Morphology and Sedimentary Processes on Continental Shelves: Advances in Technologies, Research, and Applications

Sediments, Morphology and Sedimentary Processes on Continental Shelves: Advances in Technologies, Research, and Applications

How to Cite

Li, M. Z., King, E. L. and Prescott, R. H. (2012) Seabed Disturbance and Bedform Distribution and Mobility on the Storm-Dominated Sable Island Bank, Scotian Shelf, in Sediments, Morphology and Sedimentary Processes on Continental Shelves: Advances in Technologies, Research, and Applications (eds M. Z. Li, C. R. Sherwood and P. R. Hill), John Wiley & Sons, Ltd, Chichester, West Sussex, UK. doi: 10.1002/9781118311172.ch10

Editor Information

  1. 2

    Geological Survey of Canada (Atlantic), Natural Resources Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2 Canada

  2. 3

    U. S. Geological Survey, Woods Hole, MA 02543-1598 USA

  3. 4

    Natural Resources Canada, Sidney, BC, Canada V8L 4B2

Author Information

  1. Geological Survey of Canada — Atlantic, Bedford Institute of Oceanography, 1 Challenger Drive, Dartmouth, Nova Scotia, B2Y 4A2, Canada

Publication History

  1. Published Online: 3 JAN 2013
  2. Published Print: 26 JAN 2012

ISBN Information

Print ISBN: 9781444350821

Online ISBN: 9781118311172

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Keywords:

  • bedform distribution and mobility;
  • sand ridge migration;
  • seabed disturbance;
  • sediment mobilization;
  • bedform zones;
  • Scotian shelf

Summary

Regional bathymetry maps, sidescan sonar and multibeam bathymetric surveys, sediment samples, and predictions of seabed disturbance are integrated to characterize the distribution, metrics, and mobility of bedforms on the storm-dominated Sable Island Bank, Scotian Shelf. Sand ridges cover most of Sable Island Bank with a trend of decreasing size from west to east and from offshore to onshore. Shoreface sand ridges and sand waves are active on a yearly basis on the bank top. Portions of sand ridges can migrate up to 40 m annually both to the east and west, but the mode migration is near zero. The nearshore and inner bank is exposed to high waves and strong storm-induced currents and is characterized by shoreface ridges with superimposed sand waves, megaripples, and large wave ripples. All bedforms are active in this setting. The mid- and outer-bank experiences intermediate to moderately low energy, and is characterized by moribund offshore ridges with superimposed intermittently active sand waves and active megaripples. The occurrence of large wave ripples is decreased, while periodically active sand ribbons and specks (circular shell beds) become more abundant. The bank edge and upper slope are subject to very low energy and are generally devoid of bedforms with the exception of occasional ribbons. Numerical model predictions demonstrate that hydrodynamic forcing and sediment mobilization are strongly controlled by waves and wave-current interaction during winter storms. Tidal currents alone can cause sediment mobilization at least once a year over 36% of the bank area while wave action affects 71%. The combined action of waves and tides affects 93% of the bank. Based on the relationship between seabed disturbance magnitude and bedform distribution and mobility, seven new bedform zones with unique bedform association, energy level, and mobility characteristics are proposed.