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Evolution of an advancing gravel front: observations from Vedder Canal, British Columbia

Ferguson, R.I.; Bloomer, D.J.; Church, M.


R.I. Ferguson

D.J. Bloomer

M. Church


Channelization of the lowermost part of Vedder River in 1922 initiated a natural experiment relevant to the unresolved question of how abrupt gravel–sand transitions develop along rivers. The new channel (Vedder Canal) had a fine bed and a much lower slope than the gravel-bed river immediately upstream. Changes in morphology and sedimentology as gravel advanced into and along the Canal are documented using air photos, historical surveys, and fieldwork. The channel aggraded and steepened until stabilized by occasional gravel extraction in recent decades. The deposited material fines progressively along the Canal but the gravel front has retained an abrupt appearance because it has advanced by the sequential development of discrete gravel tops on initially sandy alternate bars. Near the gravel front the bed is highly bimodal and there is a sharper drop in the extent of gravel-framework surface facies than in bulk gravel content. Ahead of the front, gravel is restricted to thin ribbons which often become buried by migrating sand. Calculations show that even though the gravel bed at the head of the Canal is almost unimodal, size-selective transport during floods can account for the strong bimodality farther downstream.


Ferguson, R., Bloomer, D., & Church, M. (2011). Evolution of an advancing gravel front: observations from Vedder Canal, British Columbia. Earth Surface Processes and Landforms, 36(9), 1172-1182.

Journal Article Type Article
Publication Date Jan 1, 2011
Deposit Date Jun 30, 2011
Journal Earth Surface Processes and Landforms
Print ISSN 0197-9337
Electronic ISSN 1096-9837
Publisher British Society for Geomorphology
Peer Reviewed Peer Reviewed
Volume 36
Issue 9
Pages 1172-1182
Keywords Gravel–sand transition, Aggradation, Bimodality, Selective transport, Sediment patches.