<div class="csl-bib-body">
<div class="csl-entry">Thorez, S., Lemmin, U., Barry, D. A., & Blanckaert, K. (2025, May 2). <i>Hydro-sedimentary processes of a lofting turbidity current revealed by gridded ADCP measurements in the field</i> [Poster Presentation]. EGU General Assembly 2025, Wien, Austria. http://hdl.handle.net/20.500.12708/223555</div>
</div>
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dc.identifier.uri
http://hdl.handle.net/20.500.12708/223555
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dc.description.abstract
Hyperpycnal (negatively buoyant) river inflows into lakes or reservoirs plunge upon entry, generating gravity-driven underflows near the bed. When the density excess of these underflows is primarily due to high sediment concentrations, they are referred to as turbidity currents. If these underflows encounter a layer of equal density, they will detach from the bed and intrude into the water column, forming an interflow. In turbidity currents, such underflow-interflow transitions often happen through a process called ‘lofting’, whereby a flow that is initially negatively buoyant undergoes a buoyancy reversal due to sedimentation of particles. Direct observations of lofting are sparse, particularly in the field. As turbidity currents transport various constituents – not only sediment, but also contaminants, nutrients, and oxygen – originating from the river or eroded from the bed, their trajectory and final destination significantly influence the water quality of lakes and reservoirs. The latter highlights the importance of studying flow transitions such as lofting.
Field measurements of the turbidity current fed by the plunging Rhône River in Lake Geneva were conducted using a boat-towed ADCP along a grid of transects. The ADCP backscatter signal was used to achieve a first order estimate for the sediment concentration.
The measured velocity field reveals that in the longitudinal direction the Rhône River turbidity current initially breaks through the Lake Geneva pycnocline, detaches from the bed, rises vertically and intrudes into the pycnocline. Additionally, in the transverse direction the outermost parts of the current peel off and similarly rise and intrude into the pycnocline. This infers the presence of lofting in both longitudinal and transverse direction. In man-made dammed-river reservoirs, river valley walls provide a high degree of transverse confinement for turbidity currents, which might suppress the development of flow processes in transverse direction, such as transverse lofting. In most natural lakes, such confinement is not present. This infers a potentially significantly different underflow-interflow transition mechanism and resulting morphological impact between reservoir and lake settings.
The estimated sediment concentrations uncover a capacity of the lofting current to transport sediment-rich water away from the turbidity current centerline in transverse direction. This might influence the local bathymetry and support levee-building.
en
dc.description.sponsorship
FWF - Österr. Wissenschaftsfonds
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dc.language.iso
en
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dc.subject
ADCP
en
dc.subject
hyperpycnal
en
dc.subject
river plume
en
dc.subject
turbidity current
en
dc.subject
gravity current
en
dc.subject
sediment transport
en
dc.subject
lofting
en
dc.subject
buoyancy reversal
en
dc.title
Hydro-sedimentary processes of a lofting turbidity current revealed by gridded ADCP measurements in the field
en
dc.type
Presentation
en
dc.type
Vortrag
de
dc.contributor.affiliation
École Polytechnique Fédérale de Lausanne, Switzerland
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dc.relation.grantno
I 6180-N
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dc.type.category
Poster Presentation
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tuw.project.title
Hyperpycnal sedimentladen river plumes in lakes
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tuw.researchTopic.id
C2
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tuw.researchTopic.id
E4
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tuw.researchTopic.name
Computational Fluid Dynamics
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tuw.researchTopic.name
Environmental Monitoring and Climate Adaptation
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tuw.researchTopic.value
30
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tuw.researchTopic.value
70
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tuw.publication.orgunit
E222-01 - Forschungsbereich Wasserbau und Umwelthydraulik
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tuw.author.orcid
0000-0002-2282-2449
-
tuw.author.orcid
0000-0001-8561-0665
-
tuw.author.orcid
0000-0002-8621-0425
-
tuw.author.orcid
0000-0002-6630-3683
-
tuw.event.name
EGU General Assembly 2025
en
tuw.event.startdate
27-04-2025
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tuw.event.enddate
02-05-2025
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tuw.event.online
On Site
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tuw.event.type
Event for scientific audience
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tuw.event.place
Wien
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tuw.event.country
AT
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tuw.event.presenter
Thorez, Stan
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wb.sciencebranch
Bauingenieurwesen
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wb.sciencebranch
Umwelttechnik
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wb.sciencebranch
Hydrologie
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wb.sciencebranch.oefos
2011
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wb.sciencebranch.oefos
2071
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wb.sciencebranch.oefos
1053
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wb.sciencebranch.value
30
-
wb.sciencebranch.value
20
-
wb.sciencebranch.value
50
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item.fulltext
no Fulltext
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item.grantfulltext
restricted
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item.openairecristype
http://purl.org/coar/resource_type/c_18co
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item.cerifentitytype
Publications
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item.languageiso639-1
en
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item.openairetype
conference poster not in proceedings
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crisitem.author.dept
E222-01 - Forschungsbereich Wasserbau
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crisitem.author.dept
École Polytechnique Fédérale de Lausanne
-
crisitem.author.dept
E222-01 - Forschungsbereich Wasserbau
-
crisitem.author.orcid
0000-0002-2282-2449
-
crisitem.author.orcid
0000-0001-8561-0665
-
crisitem.author.orcid
0000-0002-8621-0425
-
crisitem.author.orcid
0000-0002-6630-3683
-
crisitem.author.parentorg
E222 - Institut für Wasserbau und Ingenieurhydrologie
-
crisitem.author.parentorg
E222 - Institut für Wasserbau und Ingenieurhydrologie
