thumbnail

Transport of fine sediment over a coarse, immobile riverbed

Journal of Geophysical Research F: Earth Surface

By:
and
DOI: 10.1002/2013JF002925

Links

Abstract

Sediment transport in cobble-boulder rivers consists mostly of fine sediment moving over a coarse, immobile bed. Transport rate depends on several interrelated factors: boundary shear stress, the grain size and volume of fine sediment, and the configuration of fine sediment into interstitial deposits and bed forms. Existing models do not incorporate all of these factors. Approaches that partition stress face a daunting challenge because most of the boundary shear is exerted on immobile grains. We present an alternative approach that divides the bed into sand patches and interstitial deposits and is well constrained by two clear end-member cases: full sand cover and absence of sand. Entrainment from sand patches is a function of their aerial coverage. Entrainment from interstices among immobile grains is a function of sand elevation relative to the size of the immobile grains. The bed-sand coverage function is used to predict the ratio of the rate of entrainment from a partially covered bed to the rate of entrainment from a completely sand-covered bed, which is determined using a standard sand transport model. We implement the bed-sand coverage function in a morphodynamic routing model and test it against observations of sand bed elevation and suspended sand concentration for conditions of nonuniform fine sediment transport in a large flume with steady uniform flow over immobile hemispheres. The results suggest that this approach may provide a simple and robust method for predicting the transport and migration of fine sediment through rivers with coarse, immobile beds.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Transport of fine sediment over a coarse, immobile riverbed
Series title:
Journal of Geophysical Research F: Earth Surface
DOI:
10.1002/2013JF002925
Volume
119
Issue:
2
Year Published:
2014
Language:
English
Publisher:
Wiley
Contributing office(s):
Southwest Biological Science Center
Description:
24 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research F: Earth Surface
First page:
188
Last page:
211
Number of Pages:
24