Bar Development and Channel Changes in the Gravelly River Feshie, Scotland

  1. J. D. Collinson and
  2. J. Lewin
  1. R. I. Ferguson1 and
  2. A. Werritty2

Published Online: 29 APR 2009

DOI: 10.1002/9781444303773.ch14

Modern and Ancient Fluvial Systems

Modern and Ancient Fluvial Systems

How to Cite

Ferguson, R. I. and Werritty, A. (1983) Bar Development and Channel Changes in the Gravelly River Feshie, Scotland, in Modern and Ancient Fluvial Systems (eds J. D. Collinson and J. Lewin), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303773.ch14

Author Information

  1. 1

    Department of Environmental Science, University of Stirling, Stirling FK9 4LA, UK

  2. 2

    Department of Geography, University of St Andrews, St Andrews KY16 9AL, UK

Publication History

  1. Published Online: 29 APR 2009
  2. Published Print: 7 FEB 1983

ISBN Information

Print ISBN: 9780632009978

Online ISBN: 9781444303773

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Keywords:

  • bar development and channel changes in gravelly River Feshie, Scotland;
  • River Feshie in Cairngorm Mountains;
  • mid-channel bars;
  • diagonal bar evolution;
  • bar development and channel changes

Summary

Unconfined reaches of the River Feshie in the Cairngorm Mountains have active low-sinuosity moderately divided patterns in which glacial outwash gravel is reworked by floods of up to 100 m3 sec−1 on a gradient of 0·009. Alternate bars of diagonal or lateral form are characteristic; they may develop from lobate or elongate medial bars, and advance episodically during floods. A model involving diagonal-bar progradation and consequent bank erosion opposite accreting bar margins, interrupted by avulsion within the channel by chute incision or from the channel by ponded-pool overflow, is used to explain surveyed changes in one sub-reach since its initiation by avulsion in 1976. The main oblique bar front advanced 160 m by 1981 and its exposed portion changed from medial to lateral to medial through avulsion around or across the bar. The channel widened by 136% from 1977 to 1981 with bank erosion locally exceeding 10 m yr−1. Bar progradation into sloughs, and sheet transport over vegetated floodplain, led to coarsening-upward sedimentation with a falling-stage veneer of finer deposits on bar tops and lee margins. The behaviour of this wandering gravel river resembles laboratory pseudo-meandering and may represent a balance between divergent meandering and braiding tendencies.