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| Titel |
The role of the hyporheic flow on sediment transport processes : an experimental approach using particle image velocimetry |
| VerfasserIn |
Gauthier Rousseau, Angeliki Sklivaniti, Daniel Vito Papa, Christophe Ancey |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250149162
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| Publikation (Nr.) |
 EGU/EGU2017-13488.pdf |
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| Zusammenfassung |
| The study of river dynamics usually considers a turbulent stream on an impervious
bed. However, it is known that part of the total discharge takes place through the
erodible bed, especially for mountain rivers. This hyporheic flow (or subsurface flow)
is likely to play an active role in the stability of the erodible bed. The question
then arises: How does the hyporheic flow affect bed stability and thereby bed load
transport?
Monitoring hyporheic flow under natural conditions remains a key challenge.
Laboratory experiments and new measurement techniques shed new light on this
problem.
Using PIV-LIF method (Particle Image Velocimetry - Laser Induced Fluorescence) we
investigate hyporheic flows through erodible beds.
The experiment is conducted in a 2-m-long and 6-cm-width flume with 2-mm-diameter
glass beads and 4-mm-diameter natural pebbles under turbulent stream conditions.
In parallel, we develop a simple analytical model that accounts for the interaction
between the surface and subsurface flows at the bed interface. As the Reynolds
number of the hyporheic flow is fairly high (10 to 100), inertia cannot be neglected.
This leads us to use the Darcy-Forchheimer law instead of Darcy’s law to model
hyporheic flows. We show that this model is consistent with the PIV-LIF experimental
results.
Moreover, the PIV-LIF data show that hyporheic flows modify the velocity profile and
turbulence.
Our measurements and empirical model emphasize the exchange processes in
coarse-grained river for incipient sediment motion. |
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