Skip to Main content Skip to Navigation
Journal articles

Experimental migration of knickpoints: influence of style of base-level fall and bed lithology

Abstract : Knickpoints are fascinating and common geomorphic features whose dynamics influence the development of landscapes and source-to-sink systems – in particular the upstream propagation of erosion. Here, we study river profiles and associated knickpoints experimentally in a microflume filled with a cohesive substrate made of silica, water and kaolinite. We focus on the effect on knickpoint dynamics of varying the distribution of base-level fall (rate, increment, and period) and substrate strength, i.e., kaolinite content. Such simple cases are directly comparable to both bedrock and alluvial river systems. Under a constant rate of base-level fall, knickpoints of similar shape are periodically generated, highlighting self-organized dynamics in which steady forcing leads to multiple knickpoint events. Temporary shielding of the bed by alluvium controls the spacing between these unit knickpoints. Shielding is, however, not effective when base-level drops exceed alluvium thickness. While the base-level fall rate controls the overall slope of experiments, it is not instrumental in dictating the major characteristics of unit knickpoints. Instead the velocity, face slope and associated plunge pool depth of these knickpoints are all strongly influenced by lithology. The period between knickpoints is set by both alluvium thickness and base-level fall rate, allowing use of knickpoint spacing along rivers as an indicator of base-level fall rate.
Document type :
Journal articles
Complete list of metadata

Cited literature [47 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-01481371
Contributor : Jean-Louis Grimaud Connect in order to contact the contributor
Submitted on : Thursday, March 2, 2017 - 3:04:34 PM
Last modification on : Saturday, June 25, 2022 - 10:55:39 AM
Long-term archiving on: : Wednesday, May 31, 2017 - 2:43:17 PM

File

Grimaud&al2016_Knickpoints.pdf
Publisher files allowed on an open archive

Identifiers

Collections

Citation

Jean-Louis Grimaud, Chris Paola, Vaughan Voller. Experimental migration of knickpoints: influence of style of base-level fall and bed lithology. Earth Surface Dynamics, European Geosciences Union, 2016, 4, ⟨10.5194/esurf-4-11-2016⟩. ⟨hal-01481371⟩

Share

Metrics

Record views

104

Files downloads

279