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Imaging Active Mass-Wasting and Sediment Flows on a Fjord Delta, Squamish, British Columbia

  • John E. Hughes Clarke
  • Carlos R. Vidiera Marques
  • Danar Pratomo
Chapter
Part of the Advances in Natural and Technological Hazards Research book series (NTHR, volume 37)

Abstract

An active fjord head delta in Squamish British Columbia, was selected as the location for a repetitive multibeam survey program to monitor temporal evolution of the prodelta morphology. Daily resurveys in 2011 established the style and extent of submarine mass movements, their typical periodicity and the conditions associated with the most active periods. This has now been followed by an hourly resurvey program in 2012 during those most active periods to actually witness the progression of activity immediately preceding, during and subsequent to a singular event.

The delta front in depths of 20–50 m is often the apparent start point for trains of sequential erosive and depositional events associated with upslope bedform migration along prodelta channels. Heavy targets on the channel floors were monitored in 2011 and indicated rare, abrupt down channel displacements of a few hundred metres, indicating that a small subset of events involved bulk translation of the seabed. In 2011, a bottom-mounted ADCP beyond one channel mouth recorded clear turbidity current events for a subset of the channel bedform migration periods.

In 2012, using multibeam water column imaging and a rapidly dipping towed optical backscatter probe, the evolution of a descending suspended sediment plume below the overlying river plume was monitored on an hourly basis. Towards low water, that descending plume was seen to occasionally feed a near seabed higher suspended sediment layer. On the development of this layer, the water column imaging revealed a thin basal flow that lasted about an hour and corresponded directly with the period of migration of the channel floor bedforms. Delta-lip failures are associated with the upslope end of about half of the bedform trains suggesting an alternate initiating mechanism.

Keywords

Prodelta mass wasting Surface differences Cyclic steps Bedform translation Turbidity current Water column imaging 

Notes

Acknowledgements

This research has been funded by an NSERC Discovery Grant “Precise Seabed Change Monitoring” to the first author as well as research sponsorship of the Chair in Ocean Mapping at UNB from Rijkswaterstaat and Kongsberg Maritime. The professional operation of the CSL Heron was undertaken by Gordon Allison. The implementation of much of the survey component was undertaken by Steve Brucker, Ian Church, Doug Cartwright, James Muggah, Travis Hamilton and Pim Kuus. This paper significantly benefited from reviews by Peter Talling and Phil Hill.

References

  1. Brucker S, Hughes Clarke JE, Beaudoin J, Lessels C, Czotter K, Loschiavo R, Iwanowska K, Hill P (2007) Monitoring flood-related change in bathymetry and sediment distribution over the Squamish Delta, Howe Sound, British Columbia. In: Proceedings of the United States hydrographic conference 2007, 16 pp. The 2007 conference paper is maintained by the Hydrographic Society of America on their website: http://www.thsoa.org/us07papers.htm
  2. Heezen BC, Ewing M (1952) Turbidity currents and submarine slumps, and the 1929 Grand Banks earthquake. Am J Sci 250:849–873CrossRefGoogle Scholar
  3. Hickin EJ (1989) Contemporary Squamish River sediment flux to Howe Sound, British Columbia. Can J Earth Sci 26:1953–1963CrossRefGoogle Scholar
  4. Hill P (2012) Changes in submarine channel morphology and slope sedimentation patterns from repeat multibeam surveys in the Fraser River delta, western Canada. Int Assoc Sedimentol Spec Publ 44:47–70Google Scholar
  5. Hsu S-K, Kuo J, Lo C-L, Tsai C-H, Doo W-B, Ku C-Y Sibuet J-C (2008) Turbidity currents, submarine landslides and the 2006 Pingtung earthquake off SW Taiwan. Terr Atmos Ocean Sci 19(6):767–772CrossRefGoogle Scholar
  6. Hughes Clarke JE, Brucker S, Muggah, J, Church I, Cartwright D, Kuus P, Hamilton T, Pratomo D, Eisan B (2012) The Squamish ProDelta: monitoring active landslides and turbidity currents: Canadian hydrographic conference 2012, proceedings, 15 pp. The 2012 conference paper is maintained by the Canadian Hydrographic Association on their website: http://hydrography.ca/2012-conference.html
  7. Marques CRV (2012) Automatic mid-water target detection using multibeam water column. M.Sc. Eng. thesis, University of New Brunswick, 209 ppGoogle Scholar
  8. Mulder T, Syvitski JPM (1995) Turbidity currents generated at river mouths during exceptional discharges to the world oceans. J Geol 103:285–299CrossRefGoogle Scholar
  9. Parsons JD, Bush JWM, Syvitski JPM (2001) Hyperpycnal plume formation from riverine outflows with small sediment concentrations. Sedimentology 48:465–478CrossRefGoogle Scholar
  10. Paull CK, Ussler W III, Caress DW, Lundsten E, Barry J, Covault JA, Maier KL, Xu J, Augenstein S (2010) Origins of large crescent-shaped bedforms within the axial channel of Monterey Canyon. Geosphere 6:755–774CrossRefGoogle Scholar
  11. Prior DB, Bornhold BD, Wiseman WJ Jr, Lowe DR (1987) Turbidity current activity in a British Columbia fjord. Science 237:1330–1333CrossRefGoogle Scholar
  12. Syvitski JPM, Murray JW (1981) Particle interaction in fjord suspended sediment. Mar Geol 39:215–242CrossRefGoogle Scholar
  13. Xu JP, Noble MA, Rosenfeld LK (2004) In-situ measurements of velocity structure within turbidity currents. Geophys Res Lett 31:L09311. doi: 10.1029/2004GL019718 Google Scholar

Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • John E. Hughes Clarke
    • 1
  • Carlos R. Vidiera Marques
    • 1
  • Danar Pratomo
    • 1
  1. 1.Department of Geodesy and Geomatics EngineeringUniversity of New BrunswickFrederictonCanada

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