The dynamics of a gravel-sand transition

Astrid Blom; Victor Chavarrias Borras; Enrica Viparelli

Abstract

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 language	English
Pages	158
Publication status	Published - 2017
Event	10th Symposium on River coastal and estuarine morphodynamics: Back to Italy - Trento - Padova, Italy Duration: 15 Sept 2017 → 22 Sept 2017 Conference number: 10 http://cirefluvial.com/eventos_ver.php?id=246

Conference

Conference	10th Symposium on River coastal and estuarine morphodynamics
Abbreviated title	RCEM2017
Country/Territory	Italy
City	Trento - Padova
Period	15/09/17 → 22/09/17
Internet address	http://cirefluvial.com/eventos_ver.php?id=246

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

Cite this

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title = "The dynamics of a gravel-sand transition",

abstract = "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 ",

author = "Astrid Blom and {Chavarrias Borras}, Victor and Enrica Viparelli",

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; 10th Symposium on River coastal and estuarine morphodynamics : Back to Italy, RCEM2017 ; Conference date: 15-09-2017 Through 22-09-2017",

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language = "English",

pages = "158",

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T1 - The dynamics of a gravel-sand transition

AU - Blom, Astrid

AU - Chavarrias Borras, Victor

AU - Viparelli, Enrica

N1 - Conference code: 10

PY - 2017

Y1 - 2017

N2 - 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

AB - 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

M3 - Abstract

SP - 158

T2 - 10th Symposium on River coastal and estuarine morphodynamics

Y2 - 15 September 2017 through 22 September 2017

ER -

The dynamics of a gravel-sand transition

Abstract

Conference

Bibliographical note

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