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)

Brocard, Gilles; Beek, Peter van der

doi:10.1130/2006.2398(07)

Cited by 76 publications

(138 citation statements)

References 49 publications

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“…A potential method to estimate the importance of pre-glacial fluvial incision is to model river profiles based on stream-power models (Brocklehurst and Whipple, 2006). Brocard and van der Beek (2006) showed that rivers in non-glaciated catchments of the western Alps are well-described by a simple stream-power equation, such that river slope S is a power-law function of contributing drainage area A: Finally, we stress that the interpolated surface does not constitute a paleosurface (or relict landscape) such that it could be used as an absolute marker of erosion, for two reasons.…”

Section: Assessing Glacial Erosion and Reboundmentioning

confidence: 99%

A quantification of the glacial imprint on relief development in the French western Alps

Beek

Bourbon

2008

Geomorphology

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Mail: pvdbeek@ujf-grenoble.fr AbstractThe morphology of the western Alps has been strongly influenced by Quaternary glaciations.On the basis of observations of glacial morphology in the Belledonne, Grandes-Rousses, Taillefer and Pelvoux-Ecrins Massifs (south-eastern France), we reconstitute the glacial trimline and equilibrium line altitude (ELA) during the most extensive glaciation (MEG). Our best estimate of the MEG ELA is 1800±100 m. Using digital elevation models, we compare our glacial reconstruction with the relief structure of 9 major catchments draining the massifs. This number is insufficient to substantially offset topographic lowering due to regional denudation, and we conclude that the isostatic response to glacial valley carving has not increased peak elevations significantly.

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Section: Assessing Glacial Erosion and Reboundmentioning

confidence: 99%

A quantification of the glacial imprint on relief development in the French western Alps

Beek

Bourbon

2008

Geomorphology

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“…Hurtrez et al, 1999;Kirby and Whipple, 2001), and fluvial strath terraces (e.g. Pazzaglia et al, 1998;Berryman et al, 2000;Avouac, 2000, 2001;Pazzaglia and Brandon, 2001;Brocard et al, 2003;Tomkin et al, 2003;Brocard and van der Beek, 2006). For example, Lavé and Avouac (2001) and Tomkin et al (2003) tested stream erosion models using data on spatial variations in channel incision rate in the central Nepal Himalayas, and the Olympic Mountains, northwestern USA, respectively.…”

Section: Natural Experiments In Landscape Evolution 1455mentioning

confidence: 99%

Natural experiments in landscape evolution

Tucker

2009

Earth Surf Processes Landf

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A natural experiment in landscape evolution is a case study of landform development in which only one element varies significantly, and for which the driving forces, initial conditions, and/or boundary conditions are well constrained. Natural experiments provide a means of testing landscape evolution theory on the large space and time scales to which that theory applies. Natural experiments can involve either steady or transient conditions. Cases with steady conditions allow one to test predictions about the relationships among topography, erosion rates, and various attributes related to climate and material properties. Transient cases are valuable for distinguishing between models whose predictions might be similar, and therefore indistinguishable, under steady conditions. Essential ingredients of a natural experiment include minimal variation in all but one factor, good constraints on timing and/or rates, well-characterized processes, and high quality topographic data. Other useful ingredients include information about intermediate topographic states (such as a former valley profile revealed by strath terraces), and knowledge of the time history of erosion rates. In order to deepen our understanding of the physics and chemistry of longterm landscape evolution, there is a pressing need to identify natural experiments and develop the necessary databases to take advantage of them.

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“…Several studies demonstrate that significant lateral erosion in rapidly incising rivers is accomplished by large flood events (Hartshorn et al, 2002;Barbour et al, 2009) resulting from cover on the bed during extreme flood events (Turowski et al, 2008) and exposure of the bedrock walls to sediment and flow (Beer et al, 2017). Sediment cover on the bed that suppresses vertical incision and allows lateral erosion to continue unimpeded is a critical element for the development of wide bedrock valleys, as determined from modeling, field, and experimental studies (Hancock and Anderson, 2002;Brocard and Van der Beek, 2006;Johnson and Whipple, 2010). Lateral erosion that outpaces vertical incision and creates wide bedrock valleys and strath terraces has been linked to weak underlying lithology, such as shale (Montgomery, 2004;Snyder and Kammer, 2008;Schanz and Montgomery, 2016), although strath terraces certainly exist in stronger lithologies, such as quartzite (Pratt-Sitaula et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Developing and exploring a theory for the lateral erosion of bedrock channels for use in landscape evolution models

Langston

Tucker

2018

Earth Surf. Dynam.

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Abstract. Understanding how a bedrock river erodes its banks laterally is a frontier in geomorphology. Theories for the vertical incision of bedrock channels are widely implemented in the current generation of landscape evolution models. However, in general existing models do not seek to implement the lateral migration of bedrock channel walls. This is problematic, as modeling geomorphic processes such as terrace formation and hillslopechannel coupling depends on the accurate simulation of valley widening. We have developed and implemented a theory for the lateral migration of bedrock channel walls in a catchment-scale landscape evolution model. Two model formulations are presented, one representing the slow process of widening a bedrock canyon and the other representing undercutting, slumping, and rapid downstream sediment transport that occurs in softer bedrock. Model experiments were run with a range of values for bedrock erodibility and tendency towards transport-or detachment-limited behavior and varying magnitudes of sediment flux and water discharge in order to determine the role that each plays in the development of wide bedrock valleys. The results show that this simple, physicsbased theory for the lateral erosion of bedrock channels produces bedrock valleys that are many times wider than the grid discretization scale. This theory for the lateral erosion of bedrock channel walls and the numerical implementation of the theory in a catchment-scale landscape evolution model is a significant first step towards understanding the factors that control the rates and spatial extent of wide bedrock valleys.

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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)

Cited by 76 publications

References 49 publications

A quantification of the glacial imprint on relief development in the French western Alps

A quantification of the glacial imprint on relief development in the French western Alps

Natural experiments in landscape evolution

Developing and exploring a theory for the lateral erosion of bedrock channels for use in landscape evolution models

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