Reference : Controls on knickpoint migration in a drainage network of the moderately uplifted Ard...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/190050
Controls on knickpoint migration in a drainage network of the moderately uplifted Ardennes Plateau, Western Europe
English
Beckers, Arnaud mailto [Université de Liège > Département de géographie > Géomorphologie et Géologie du Quaternaire >]
Bovy, Benoît mailto [Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe infra-rouge de phys. atmosph. et solaire (GIRPAS) >]
Hallot, Eric mailto [Université de Liège > Département de géographie > Hydrographie et géomorphologie fluviatile >]
Demoulin, Alain mailto [Université de Liège > Département de géographie > Unité de géographie physique et quaternaire (UGPQ) >]
2015
Earth Surface Processes and Landforms
John Wiley & Sons, Inc
40
357-374
Yes (verified by ORBi)
International
0197-9337
1096-9837
Chichester
United Kingdom
[en] fluvial incision ; knickpoint migration ; channel width ; rock resistance control ; erosion threshold ; Ardennes
[en] Much research has been devoted to the development of numerical models of river incision. In settings where bedrock channel erosion prevails, numerous studies have used field data to calibrate the widely acknowledged stream power model of incision and to discuss the impact of variables that do not appear explicitly in the model’s simplest form. However, most studies have been conducted in areas of active tectonics, displaying a clear geomorphic response to the tectonic signal. Here, we analyze the traces left in the drainage network 0.7 My after the Ardennes region (western Europe) underwent a moderate 100–150 m uplift. We identify a set of
knickpoints that have traveled far upstream in the Ourthe catchment, following this tectonic perturbation. Using a misfit function based on time residuals, our best fit of the stream power model parameters yields m= 0.75 and K = 4.63 × 10-8 m-0.5y-1. Linear regression of the
model time residuals against quantitative expressions of bedrock resistance to erosion shows that this variable does not correlate significantly with the residuals. By contrast, proxies for position in the drainage system prove to be able to explain 76% of the residual variance.
High time residuals correlate with knickpoint position in small tributaries located in the downstream part of the Ourthe catchment,where some threshold was reached very early in the catchment’s incision history. Removing the knickpoints stopped at such thresholds from the
data set, we calculate an improved m= 0.68 and derive a scaling exponent of channel width against drainage area of 0.32, consistent with the average value compiled by Lague for steady state incising bedrock rivers.
http://hdl.handle.net/2268/190050

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