Lake Geneva sediments reveal anthropogenic activities and some effects of climate change in the Rhone River watershed.

Préparation d’un prélèvement de sédiments du Léman à l’aide d’un carottier de 6 m de long, par une équipe de l’Université de Genève, aidée de spécialistes de l’ETHZ (photo : J.-L. Loizeau).

 “The team of the Earth Sciences Section, assisting ETHZ colleagues in the collection of long cores (6 m) of sediments in Lake Geneva (Photo Robert Hofmann).”

As part of a Sinergia* project financed by the Swiss National Science Foundation on the production and transport of sediments in the Rhône Valley in Valais and their deposition in Lake Geneva, the authors of a study** published in "Nature Scientific Reports" show the complex relationships between changes in sediment accumulation rates in the lake and the development of hydroelectric facilities in the catchment area but offset by accelerated glacier melting. The effect of the 2008 economic crisis can also be seen in the sedimentary inputs to the lake.

Researchers from the Department of Earth Sciences and the F.-A. Forel Department of Environmental and Water Sciences, also a member of the Institute for Environmental Sciences (Tiago Silva, Stéphanie Girardclos and Jean-Luc Loizeau) have particularly highlighted variations in sediment accumulation rates in the Rhône Delta, with a decrease of sediment loads after the 1960s, and an increase of inputs at the end of the 1980s.

Understanding sediment dynamics is particularly important for river management, for example in flood prevention.

(*) « SEDFATE: Sediment fate in a changing watershed during the Anthropocene » is a collaboration between the Institute of Earth Surface Dynamics of the University of Lausanne, the Department of Civil, Environmental and Geomatic Engineering of ETH Zurich, the Department of Earth Sciences, the Institute for Environmental Science and the Department F.-A. Forel for Environmental and Aquatic Sciences of the University of Geneva, and the Institute of Geological Sciences of the University of Bern.

(**) S. N. Lane, M. Bakker, A. Costa, S. Girardclos, J.-L. Loizeau, P. Molnar, T. Silva, L. Stutenbecker and F. Schlunegger: Making stratigraphy in the Anthropocene: climate change impacts and economic conditions controlling the supply of sediment to Lake Geneva (Scientific Reports, 2019). doi: 10.1038/s41598-019-44914-9

7 July 2019

News 2019