Skip to Main Content
Book Chapter

Influence of incision rate, rock strength, and bedload supply on bedrock river gradients and valley-flat widths: Field-based evidence and calibrations from western Alpine rivers (southeast France)

By
G.Y. Brocard
G.Y. Brocard
Laboratoire de Géodynamique des Chaînes Alpines, Université Joseph Fourier, 38 041 Grenoble, France
Search for other works by this author on:
P.A. van der Beek
P.A. van der Beek
Laboratoire de Géodynamique des Chaînes Alpines, Université Joseph Fourier, 38 041 Grenoble, France
Search for other works by this author on:
Published:
January 01, 2006

Several process-based models of river incision have been proposed in recent years that attempt to describe fluvial landform development. Although some field tests have been performed, more data are required to test the ability of these models to predict the observed evolution of fluvial landforms. We have investigated several tens of rivers located in the French western Alps that flow across folded sedimentary rocks with strongly contrasting rock strengths. These rivers record significant variations in some of the parameters controlling river incision, notably bedrock lithology, stream power, incision rate, and sediment flux, potentially allowing discrimination between existing models. Variations in incision rates are driven by variations in the amount of disequilibrium introduced in the river profiles during the last glaciation. We use diagnostic indices to investigate transport- and detachment-limited conditions, which include the channel morphology, the occurrence of lithogenic knickpoints, the continuity of alluvial and bedrock reaches, and the slope-area scaling of the river long profile. We observe transitions from detachment-limited to transport-limited conditions with increasing discharge/drainage area and decreasing incision rate. Bedrock strength influences the location of the transition predictably. The formation of transport-limited rivers coincides with the development of a valley flat wider than the active channel, which accommodates variations in bedrock strength, stream power, and incision rate along the transport-limited reaches. We propose and calibrate a model for the development of valley flats along transport-limited rivers and explore some properties of landscape development in mountain ranges controlled by transport-limited rivers.

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

Figures & Tables

Contents

GSA Special Papers

Tectonics, Climate, and Landscape Evolution

Sean D. Willett
Sean D. Willett
Search for other works by this author on:
Niels Hovius
Niels Hovius
Search for other works by this author on:
Mark T. Brandon
Mark T. Brandon
Search for other works by this author on:
Donald M. Fisher
Donald M. Fisher
Search for other works by this author on:
Geological Society of America
Volume
398
ISBN print:
9780813723983
Publication date:
January 01, 2006

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