EESS talk on "Sediment transfer in the Rhône Basin: the role of localized Alpine severe storms on the triggering of turbidity currents in Lake Geneva"

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Event details

Date and time 17.11.2020 12:1513:00  
Place and room
ZOOM
Speaker Dr François Mettra, scientist, Ecological Engineering Laboratory, EPFL
Category Conferences - Seminars
Abstract:
In the Eastern Lake Geneva, the sublacustrine Rhône delta presents a deep canyon, the Rhône Canyon. Former studies and recent observations show that winter underflows and summer turbidity currents are frequent in the Rhône Canyon. Winter underflows are long-lasting and slow, whereas summer turbidity currents are brief and occasionally showing high velocities. In this talk, we revisit the three different event types triggering turbidity currents in the Rhône Canyon in Summer: large-scale floods, sublacustrine slides on the Rhône delta and high concentration sediment clouds traveling in the Rhône River due to localized severe storms.

After an introduction on the Rhône Canyon underflows and seasonal characteristic of sediment export in the Rhône Basin, the evidence of isolated storms leading to turbidity currents in deep Lake Geneva is shown using simultaneous observations from the Rhône Canyon and the Rhône Basin. Then, preliminary estimations of the frequency of turbidity currents relative to their type of triggering and their significant influence on the total sediment load that ends in Lake Geneva are discussed. Finally, future work on the sediment concentration estimations in the Rhône and bathymetry measurements on the sublacustrine Rhône delta are briefly mentioned.

Short biography:
François Mettra is a scientist at the Ecological Engineering Laboratory (ECOL), headed by Prof. D. Andrew Barry, of the Swiss Federal Institute of Technology Lausanne (EPFL). After studying fluid mechanics and environmental hydraulics, he earned an engineering diploma from the Engineering School of Hydraulics and Mechanics Grenoble, France and his Masters from University of Grenoble Alps, France. He moved to Lausanne where he completed his PhD on the experimental study of bedload transport in steep channels at the Environmental Hydraulics Laboratory of EPFL. He continued his career as a weather forecaster and hydrologist in the private sector and as a lecturer at the University of Lausanne where his research was focused on sediment exports in small Alpine catchments. His recent interest on the influence of high sediment load from Alpine rivers on turbidity currents in Lake Geneva brought him to study lake circulation and density currents at ECOL laboratory.

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Practical information

  • General public
  • Free
  • This event is internal

Organizer

  • EESS - IIE

Contact

Tags

Rhône River Lake Geneva turbidity currents suspended sediment load

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