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Slope‐induced changes in channel character along a gravel‐bed stream: The Allt Dubhaig, Scotland

Slope‐induced changes in channel character along a gravel‐bed stream: The Allt Dubhaig, Scotland Changes in channel character along a small river in the Scottish Highlands are described using measurements in seven reaches over a 3 km length with no significant tributaries but a decline in slope from 0.02 to 0.00015 because of local baselevel control. This decline in slope is associated with rapid downstream fining of the gravel bed followed by an abrupt transition to a sand bed. The channel pattern alters progressively rather than abruptly, in the sequence (1) near‐braided, (2) meandering with active point‐bar chutes, (3) meandering with active outer‐bank talweg, (4) stable equiwidth sinuous. The changes in channel pattern and hydraulic geometry are predicted better by rational approaches based on critical shear stress or other physical concepts than by purely empirical discriminant or trend equations. Measurements in five reaches confirm a downstream decrease in shear stress and the amount and calibre of bedload. It is argued that the downstream changes in channel character in this stream are induced by profile concavity inherited from deglacial conditions, are typical of many streams in mountainous areas and can be understood in terms of slope‐induced changes in hydraulic properties. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Earth Surface Processes and Landforms Wiley

Slope‐induced changes in channel character along a gravel‐bed stream: The Allt Dubhaig, Scotland

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References (35)

Publisher
Wiley
Copyright
Copyright © 1991 John Wiley & Sons, Ltd
ISSN
0197-9337
eISSN
1096-9837
DOI
10.1002/esp.3290160108
Publisher site
See Article on Publisher Site

Abstract

Changes in channel character along a small river in the Scottish Highlands are described using measurements in seven reaches over a 3 km length with no significant tributaries but a decline in slope from 0.02 to 0.00015 because of local baselevel control. This decline in slope is associated with rapid downstream fining of the gravel bed followed by an abrupt transition to a sand bed. The channel pattern alters progressively rather than abruptly, in the sequence (1) near‐braided, (2) meandering with active point‐bar chutes, (3) meandering with active outer‐bank talweg, (4) stable equiwidth sinuous. The changes in channel pattern and hydraulic geometry are predicted better by rational approaches based on critical shear stress or other physical concepts than by purely empirical discriminant or trend equations. Measurements in five reaches confirm a downstream decrease in shear stress and the amount and calibre of bedload. It is argued that the downstream changes in channel character in this stream are induced by profile concavity inherited from deglacial conditions, are typical of many streams in mountainous areas and can be understood in terms of slope‐induced changes in hydraulic properties.

Journal

Earth Surface Processes and Landforms – Wiley

Published: Feb 1, 1991

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