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TitleSediment transport processes and bedform mobility during major storms on Grand Banks
AuthorLi, M Z; Prescott, R H; Wu, Y; King, E L; Han, G
SourceOcean Sciences Meeting 2014, abstracts; 2014 p. 1
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20130335
PublisherAmerican Geophysical Union
MeetingAmerican Geophysical Union's Ocean Sciences Meeting 2014; Honolulu; US; February 22-29, 2014
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatjpg
ProvinceEastern offshore region
AreaGrand Banks
Subjectsmarine geology; storms; storm deposits; bedforms; bedform movement; sediment transport; transportation; submarine transport
ProgramMarine Geohazards, Public Safety Geoscience
LinksOnline - En ligne
AbstractSevere 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.
Summary(Plain Language Summary, not published)
Severe winter storms and strong ocean currents create and mobilize various bedforms on the Grand Banks, Newfoundland. Seabed samples and geophysical data are used to establish the distribution and morphology of major bedforms. Model-predicted wave, tidal and ocean currents for 22 major storms were used in a sediment transport model to predict seabed shear stresses and sediment transport. These results are then used to assess mobility of bedforms. The storm impact is mainly determined by wind speed, storm track and how fast the storm moves. Maximum significant wave heights reach ~14 m and are to NE during major storms. Surface wind-driven currents at the peaks of storms are dominantly to the SE and reach as high as 1.4 m/s. Storms cause wide occurrence of significant sediment transport on the Grand Banks and maximum flux reaches about 2 kg/m/s. Most bedforms on Grand Banks should be intermittently activated during major storms.
GEOSCAN ID293346