CGRG Bibliography of Canadian Geomorphology
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Author : Ashmore, P.; and Buffin-Bélanger, T.
Date : 2008.
Title : Flow versus morphological control of particle movement in gravel-bed rivers.
Publication : Joint Annual Meeting of the Canadian Geophysical Union and the Canadian Geomorphology Research Group. May 11-14, Banff, Alberta.
Issue :
Page(s) :
Abstract
Bed material transport can be viewed as the aggregate displacement of individual bed particles and measurement of the number and length of displacements is one approach to estimating bedload flux. These particle displacements also constitute the process by which major elements of bed topography (e.g. bars and pools) develop and evolve. At present, there is only rudimentary understanding of the interaction between particle displacements and bedform development in gravel-bed rivers. Displacement of particles involves both hydraulic control and morphological constraints and the significance of each of these effects may vary with flow stage. However, at channel-forming flows, the longitudinal scale and pattern of displacements must affect the characteristic morphology and particles deposited within the bars are then constrained in subsequent movements by the bar kinetics. These relationships have been investigated using flume experiments in simple alternate bar channels with well-defined bar wavelengths and constant discharge. In complex (braided) morphology under diurnal discharge variation the controls are less clear. Particles tend to move incrementally over short distances but displacement lengths tend to increase with total discharge in the river. However, particles move rapidly and continuously through confluence scour pools and deposit on the bar immediately downstream. The kinetics of particle movement and bedform development at bar scale requires much more empirical and theoretical development and studies of migrating aeolian dunes may be a useful analogue.
Bibliography of Canadian Geomorphology