The dynamics of a gravel-sand transition

Astrid Blom, Victor Chavarrias Borras, Enrica Viparelli

Research output: Contribution to conferenceAbstractScientific


A gravel-sand transition (GST) seems to be the result of a gravel wedge. Such a wedge can prograde, halt, and even retreat. It is typical of an ungraded or transient reach (Blom et al., 2016), where profile concavity and downstream fining can be much stronger than in a graded or equilibrium river reach. The GST migration speed decreases in time and is likely of the order of a few meters or less per year. The effect of abrasion on GST migration is limited to mainly affecting the sand and silt load transported into the sand-bed reach and so its slope. Our simple GST migration model describes GST dynamics fairly well. It provides an estimate of the time scale of GST migration and a criterion for the onset for a GST to halt or retreat. We recommend analysis of temporal change in bed elevation and bed surface texture in GST zones, and the development of new techniques to measure the bed surface texture to assess GST dynamics in the field

Original languageEnglish
Publication statusPublished - 2017
Event10th Symposium on River coastal and estuarine morphodynamics: Back to Italy - Trento - Padova, Italy
Duration: 15 Sep 201722 Sep 2017
Conference number: 10


Conference10th Symposium on River coastal and estuarine morphodynamics
Abbreviated titleRCEM2017
CityTrento - Padova
Internet address

Bibliographical note

Host publication:The 10th Symposium on River, Coastal and Estuarine Morphodynamics, Trento-Padova, 15-22 September 2017, Book of Abstracts

Editors: Lanzoni, S., Redolfi, M., Zolezzi, G.
ISBN (Print): 978-88-8443-752-5


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