Skip to Main Content
Book Chapter

Tracer pebble entrainment and deposition loci: influence of flow character and implications for riffle-pool maintenance

By
D. J. Milan
D. J. Milan
School of Environment, University of Gloucestershire, Cheltenham GL50 4AZ, UK (e-mail: dmilan@glos.ac.uk)
Search for other works by this author on:
G. L. Heritage
G. L. Heritage
Division of Geography, School of Environmental and Life Sciences, University of Salford, Manchester, M5 4WT, UK
Search for other works by this author on:
A. R. G. Large
A. R. G. Large
Department of Geography, University of Newcastle upon Tyne NE1 7RU, UK
Search for other works by this author on:
Published:
January 01, 2002

Abstract

This paper considers the influence of flow character upon scour and deposition loci of tracer clasts in a gravel-bed river, and discusses implications for riffle–pool maintenance. Overall, bars were found to be the dominant depositional zones where over 54% of the tracer clasts accumulated during a 13-month period, followed by riffles (31%) and, finally, pools (<15%). Variability in the location of scour and deposition zones were apparent and could be broadly linked to four flow categories: (i) low-magnitude, high-frequency flows below 29% bankfull appeared responsible for intra-unit re-distribution of sediment particles; (ii) medium-magnitude and -frequency flows (up to 70% bankfull) appeared capable of inter-unit transfer, with pool scour and immediate deposition on riffle heads downstream, and some movement from riffles to bar edges and heads; (iii) high-magnitude, low-frequency flows (70–90% bankfull) appeared capable of riffle–riffle transport, with routing around bar edges; and (iv) very high-magnitude, very low-frequency flows (bankfull and over) capable of bar to bar transport and clast transport distances exceeding the length of a single riffle–pool unit. Tracers originating from riffles do not appear to be fed into pools on the outside of meander bends, instead they appear to be routed over shallower bar surfaces. High competence and low sediment supply explains the coarse nature of the pools (D50 =110 mm) in comparison to the riffles (D50 = 85 mm). An improved understanding of the sediment transport mechanisms operating during different flood types is needed to better predict morphological response to changes in hydrological regime and sediment

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables

Contents

Geological Society, London, Special Publications

Sediment Flux to Basins: Causes, Controls and Consequences

S.J. Jones
S.J. Jones
University of Durham, UK
Search for other works by this author on:
L.E. Frostick
L.E. Frostick
University of Hull, UK
Search for other works by this author on:
Geological Society of London
Volume
191
ISBN electronic:
9781862394391
Publication date:
January 01, 2002

GeoRef

References

Related

A comprehensive resource of eBooks for researchers in the Earth Sciences

This Feature Is Available To Subscribers Only

Sign In or Create an Account

This PDF is available to Subscribers Only

View Article Abstract & Purchase Options

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

Subscribe Now