Controls on knickpoint migration in a drainage network of the moderately uplifted Ardennes Plateau, Western Europe

Abstract

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. Copyright © 2014 John Wiley & Sons, Ltd.

Patterns of Quaternary uplift of the Corinth rift southern border (N Peloponnese, Greece) revealed by fluvial landscape morphometry

“…However, possibly because the control of K on steepness is damped by sorting and attrition effects on bedload grain size with distance, the lower segments of the I<rios and Trikalitikos do not show the low steepness expected from their lithological conditions. This not only confirms the minor role of bedrock resistance to erosion in the long-term process of river incision (Roberts and White, 2010;Whittaker and Boulton, 2012;Beckers et al, 2014), but also shows that, except in the far west of the study area, the current episode of uplift is more intense than the previous one.…”

Applying Pattern Oriented Sampling in current fieldwork practice to enable more effective model evaluation in fluvial landscape evolution research

“…Beckers et al 2015) or reliably reconstructed and dated palaeosurfaces (e.g. For example, when incision over time is the main focus, it may be possible to determine surfaces within the landscape from which incision is likely to have started using modern land-surface DEMs as a starting point, such as relict long profiles (e.g.…”

“…Evidence for catchment response to climate change can be seen by comparing the coincidence of fossil or isotope based climatic reconstructions (e.g. Table I, Beckers et al 2015). Lewis et al 2001;Schmitz and Pujalte 2007).…”

“…chi plots, hypsometric integrals, geophysical relief, R/SRe.g. Berlin and Anderson 2007;Beckers et al 2015) and evaluate the role of additional controls on incision (e.g. Significantly more work is needed to quantify the match between field and modelled data in relation to long profiles however.…”

“…For example, when incision over time is the main focus, it may be possible to determine surfaces within the landscape from which incision is likely to have started using modern land-surface DEMs as a starting point, such as relict long profiles (e.g. Beckers et al 2015) or reliably reconstructed and dated palaeosurfaces (e.g. Fuchs et al 2012).…”