Wave train model for knickpoint migration

Type Article
Date 2009-05
Language English
Author(s) Loget Nicolas1, 2, Van Den Driessche Jean3
Affiliation(s) 1 : IFREMER, French Res Inst Exploitat Sea, DRO GM, F-29280 Plouzane, France.
2 : Coll France, Chaire Geodynam, F-13545 Aix En Provence, France.
3 : Univ Rennes 1, UMR 6118, F-35042 Rennes, France.
Source Geomorphology (0169-555X) (Elsevier Science Bv), 2009-05 , Vol. 106 , N. 3-4 , P. 376-382
DOI 10.1016/j.geomorph.2008.10.017
WOS© Times Cited 85
Keyword(s) Knickpoint, Migration rate, Wave train, Messinian Salinity Crisis, Base level drop
Abstract Rivers respond to a drop in their base level by incising the topography. The upstream propagation of an incision, as usually depicted by a knickpoint migration, is thought to depend on several parameters such as the drainage area, lithology, and the amplitude of the base level drop. We first investigate the case of the Messinian Salinity Crisis that was characterized by the extreme base level fall (1500 m) of the Mediterranean Sea at the end of the Miocene. The response of drainage areas of three orders of magnitude (10(3) to 10(6) km(2)) highlights the dominant role of the drainage area (with a square root relationship) in controlling the knickpoint migration after a base level fall. A compilation of mean rates of knickpoint propagation for time durations ranging from 10(2) to 10(7) years displays a similar relationship indicating that successive wave trains of knickpoint can migrate in a river: first, wave trains linked to the release of the alluvial cover and then, wave trains related to the bedrock incision, which correspond to the real time response of rivers. Wave trains with very low retreat rates (long lived knickpoints >1 My) rather correspond to the response time of regional landscape. (C) 2008 Elsevier B.V. All rights reserved.
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