Present address: P. V. Villard, Geomorphic Solutions, 141 Brunel Road, Mississauga, Ontario, Canada L4Z 1X3.
Bar and dune development during a freshet: Fraser River Estuary, British Columbia, Canada
Article first published online: 11 JUL 2005
Volume 52, Issue 4, pages 737–756, August 2005
How to Cite
VILLARD, P. V. and CHURCH, M. (2005), Bar and dune development during a freshet: Fraser River Estuary, British Columbia, Canada. Sedimentology, 52: 737–756. doi: 10.1111/j.1365-3091.2005.00721.x
- Issue published online: 11 JUL 2005
- Article first published online: 11 JUL 2005
- Manuscript received 2 January 2004; revision accepted 8 April 2005
- estuarine sedimentation;
- sand bar;
- sand transport
Bi-weekly multi-track sonar surveys collected along a 2-km reach of the estuarine South Arm of the Fraser River, British Columbia, Canada, during seasonal high flows document the initiation, development and interaction of dune and bar morphologies. Bedforms of several scales developed in well-delineated fields. Bedforms that appear to fit accepted equilibrium depth-scaling developed in the main channel during rising discharge when there was little local aggradation. During the rising stage, a bar also formed along the tidal shelf of the channel, migrated downstream and expanded into the main channel. Dunes that formed along the bar crest, a region of rapid deposition, lagged flow conditions and were larger than expected based on depth-scaling relations. The larger dunes developed simultaneously, although bar growth lagged dune development and was initially partially obscured by the more rapidly developing dune field. It appears that rapid deposition enhances dune development along the channel tidal shelf to dimensions larger than would be expected by simple depth-scaling rules. Smaller dunes that fit equilibrium depth-scaling relations re-established themselves throughout the study area during falling discharge when there was again little or no aggradation. Bed-material transport rates estimated from the migration rates of the large dunes suggest that, at high flows, the dunes transport the majority of the material found within the bar.