Knickpoint retreat and transient bedrock channel morphology triggered by base-level fall in small bedrock river catchments: The case of the Isle of Jura, Scotland

Geomorphology ◽  
2013 ◽  
Vol 180-181 ◽  
pp. 1-9 ◽  
Author(s):  
Miguel Castillo ◽  
Paul Bishop ◽  
John D. Jansen
Keyword(s):  
Channel Morphology ◽  
Base Level ◽  
Bedrock Channel ◽  
River Catchments

scholarly journals A probabilistic framework for the cover effect in bedrock erosion

2016 ◽  
Author(s):  
Jens M. Turowski ◽  
Rebecca Hodge
Keyword(s):  
Time Scales ◽  
Channel Morphology ◽  
Scale Model ◽  
Probabilistic Framework ◽  
Channel Dynamics ◽  
Base Level ◽  
Bedrock Channel ◽  
Bedrock Erosion ◽  
Long Time ◽  
Bedrock Channels

Abstract. The cover effect in fluvial bedrock erosion is a major control on bedrock channel morphology and long-term channel dynamics. Here, we suggest a probabilistic framework for the description of the cover effect that can be applied to field, laboratory and modelling data and thus allows the comparison of results from different sources. The framework describes the formation of sediment cover as a function of the probability of sediment being deposited on already alleviated areas of the bed. We define benchmark cases and suggest physical interpretations of deviations from these benchmarks. Furthermore, we develop a reach-scale model for sediment transfer in a bedrock channel and use it to clarify the relations between the sediment mass residing on the bed, the exposed bedrock fraction and the transport stage. We derive system time scales and investigate cover response to cyclic perturbations. The model predicts that bedrock channels achieve grade in steady state by adjusting bed cover. Thus, bedrock channels have at least two characteristic time scales of response. Over short time scales, the degree of bed cover is adjusted such that they can just transport the supplied sediment load, while over long time scales, channel morphology evolves such that the bedrock incision rate matches the tectonic uplift or base level lowering rate.

scholarly journals A probabilistic framework for the cover effect in bedrock erosion

2017 ◽  
Vol 5 (2) ◽  
pp. 311-330 ◽  
Author(s):  
Jens M. Turowski ◽  
Rebecca Hodge
Keyword(s):  
Channel Morphology ◽  
Scale Model ◽  
Probabilistic Framework ◽  
Channel Dynamics ◽  
Base Level ◽  
Bedrock Channel ◽  
Sediment Mass ◽  
Bedrock Erosion ◽  
Long Timescales ◽  
Bedrock Channels

Abstract. The cover effect in fluvial bedrock erosion is a major control on bedrock channel morphology and long-term channel dynamics. Here, we suggest a probabilistic framework for the description of the cover effect that can be applied to field, laboratory, and modelling data and thus allows the comparison of results from different sources. The framework describes the formation of sediment cover as a function of the probability of sediment being deposited on already alluviated areas of the bed. We define benchmark cases and suggest physical interpretations of deviations from these benchmarks. Furthermore, we develop a reach-scale model for sediment transfer in a bedrock channel and use it to clarify the relations between the sediment mass residing on the bed, the exposed bedrock fraction, and the transport stage. We derive system timescales and investigate cover response to cyclic perturbations. The model predicts that bedrock channels can achieve grade in steady state by adjusting bed cover. Thus, bedrock channels have at least two characteristic timescales of response. Over short timescales, the degree of bed cover is adjusted such that the supplied sediment load can just be transported, while over long timescales, channel morphology evolves such that the bedrock incision rate matches the tectonic uplift or base-level lowering rate.

Bedrock channel morphology

2001 ◽  
Vol 113 (9) ◽  
pp. 1205-1212 ◽  
Author(s):  
Ellen E. Wohl ◽  
David M. Merritt
Keyword(s):  
Channel Morphology ◽  
Bedrock Channel

Numerical Simulation of Effects of Sediment Supply on Bedrock Channel Morphology

2016 ◽  
Vol 142 (7) ◽  
pp. 04016014 ◽  
Author(s):  
T. Inoue ◽  
T. Iwasaki ◽  
G. Parker ◽  
Y. Shimizu ◽  
N. Izumi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Channel Morphology ◽  
Sediment Supply ◽  
Bedrock Channel

Linkages Between Lithology, Bedrock River Morphology, Alluvial Cover, and Riparian Vegetation Abundance in Canyons

2019 ◽  
Author(s):  
Daniel N. Scott ◽  
José Ortega-Becerril
Keyword(s):  
Riparian Vegetation ◽  
Channel Morphology ◽  
Advisory Board ◽  
Rock Properties ◽  
River Morphology ◽  
Field Observations ◽  
Bedrock Rivers ◽  
Bedrock Channel ◽  
Spanish Pyrenees ◽  
Sediment Cover

The EarthArXiv Advisory Board has accepted the authors request to withdrawal this paper based on a declaration of major errors in the work that the authors feel cannot be corrected. Narrow, incised canyons exemplify an end member of bedrock rivers in which incision has outpaced widening and morphologic adjustments are sensitive to changes in the balance between driving erosive forces and lithologic resistance to erosion. We use canyons as an ideal environment to observe how variability in rock properties influences bedrock channel morphology and resulting sediment cover and riparian vegetation abundance. We present statistical analysis of field observations from canyons in the Spanish Pyrenees and Utah Canyonlands to explore these linkages.

scholarly journals Steady state, continuity, and the erosion of layered rocks

2016 ◽  
Author(s):  
Matija Perne ◽  
Matthew D. Covington ◽  
Evan A. Thaler ◽  
Joseph M. Myre
Keyword(s):  
Steady State ◽  
Inverse Function ◽  
General Description ◽  
Mathematical Tool ◽  
Uplift Rate ◽  
Stream Power ◽  
Direction Parallel ◽  
Base Level ◽  
Bedrock Channel ◽  
Special Case

Abstract. Considerations of landscape steady state have substantially informed our understanding of the relationships between landscapes, tectonics, climate, and lithology. Topographic steady state, where topography is fixed in time, is a particularly important tool in the interpretation of landscape features, such as bedrock channel profiles, within a context of uplift patterns and rock strength. However, topographic steady state cannot strictly be attained in a landscape with layered rocks with non-vertical contacts. Using a combination of analytical solutions, stream erosion simulations, and full landscape evolution simulations, we show that an assumption of channel continuity, where channel retreat rates in the direction parallel to a contact are equal above and below the contact, provides a more general description of steady state landscapes in layered rocks. Topographic steady state is a special case of the steady state derived from continuity. Contrary to prior work, continuity predicts that channels will be steeper in weaker rocks in the case of subhorizontal rock layers when the stream power erosion exponent n < 1. For subhorizontal layered rocks with different erodibilities, continuity also predicts larger slope contrasts than would be predicted by topographic steady state. Continuity steady state is a type of flux steady state, where uplift is balanced on average by erosion. If uplift rate is constant, continuity steady state is perturbed near base level. These perturbations decay over a length scale that is an inverse function of the contrast in erodibility, such that erodibility contrasts of more than approximately a factor of three lead to rapid decay. Though examples explored here utilze the stream power erosion law, continuity steady state provides a general mathematical tool that can be used to explore the development of landscapes in layered rocks using any erosion model.

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