Completed projects

Human impact and recent climate change from clastic lacustrine records

Quantifying human impact and recent climate change using clastic sediments from lacustrine records in Western Switzerland

Map of Switzerland showing Lake Biel and Lake Geneva with respective Aare river and Rhône river alpine catchments (blue contour).

Description : This research project aims to reconstruct recent past changes in clastic input from two peri-alpine lakes (Lake Geneva and Lake Biel) with a focus on flood deposit analysis. The frequency and sedimentary characteristics of these beds will be analyzed and linked to historical large flood events, and interpreted using available instrumental meteorological and hydrological records to establish a quantified ‘flood event typology’. Special attention will be given to analysis and comparison of flood deposit record before and after the regional river management was put in place, which will reveal how human-made modifications of Rhône and Aare river systems changed the clastic input and impacted sedimentological processes controlling the formation of Rhône and Aare deltas in Lake Geneva and Lake Biel, respectively.

The research proposes a bipartite - geophysical and sedimentological - approach to investigate the clastic sediment and flood record. Detailed 3.5 kHz seismic reflexion survey will allow the quasi-3D imaging of the basin geometry, and sediment cores, chosen at key locations from seismic surveys, will calibrate seismic data and provide material to date and analyze the lacustrine sediment record with confirmed petrophysical and sedimentological methods. These measurements will generate a) seismic site survey for coring, b) seismic stratigraphy data and volumetric quantification of past few centuries/millennia, and c) detailed sediment record of clastic input and flooding events that will be linked to historic human impact and paleoclimatology, and analyzed along with available instrumental hydrologic and climatic data. The distinct human impact history of Lake Geneva and Lake Biel catchments, as well as their contrasted position (proximal vs. distal) in peri-alpine river systems, offers an excellent opportunity to compare and understand clastic sedimentology processes from similar climate and matching time scales.

Framework/Financing : projet SNSF nr. 200021-121666/1 (2009-2011).

Collaborations : co-applicant Daniel Ariztegui (Departement of Geology and Paleontology, University of Geneva), co-applicant Stéphane Goyette (C3i Climatic Change and Climate Impacts, Geneva Environment Institute, University of Geneva), Flavio Anselmetti (EAWAG Dübendorf), Adrian Gilli (ETH Zurich) .

Supervisor and colleagues directly involved : Stéphanie Girardclos, Daniel Ariztegui.