Subaquatic slope instabilities: the aftermath of river correction and artificial dumps in Lake Biel (Switzerland)

Article Article scientifique Article Subaquatic slope instabilities: the aftermath of river correction and artificial dumps in Lake Biel (Switzerland) eng 2020 author Dubois Nathalie author Råman Vinnå Love author Rabold Marvin author Hilbe Michael author Anselmetti Flavio S. author Wüest Alfred author Meuriot Laetitia author Jeannet Alice 594896 author Girardclos Stéphanie 40596 971-990 10.1111/sed.12669 1365-3091 https://onlinelibrary.wiley.com/doi/abs/10.1111/sed.12669 River engineering projects are developing rapidly across the globe, drastically modifying water courses and sediment transfer. Investigation of the impact of engineering works focuses usually on short-term impacts, thus a longer-term perspective is still missing on the effects that such projects have. The ‘Jura Water Corrections' – the largest river engineering project ever undertaken in Switzerland – radically modified the hydrological system of Lake Biel in the 19th and 20th Century. The deviation of the Aare River into Lake Biel more than 140 years ago, in 1878, thus represents an ideal case study to investigate the long-term sedimentological impacts of such large-scale river rerouting. Sediment cores, along with new high-resolution bathymetric and seismic reflection datasets were acquired in Lake Biel to document the consequences of the Jura Water Corrections on the sedimentation history of Lake Biel. Numerous subaquatic mass transport structures were detected on all of the slopes of the lake. Notably, a relatively large mass transport complex (0_86 km2) was observed on the eastern shore, along the path of the Aare River intrusion. The large amount of sediment delivered by the Aare River since its deviation into the lake likely caused sediment overloading resulting in subaquatic mass transport. Alternatively, the dumping since 1963 in a subaquatic landfill of material excavated during the second phase of river engineering, when the channels flowing into and out of Lake Biel were widened and deepened, might have triggered the largest mass transport, dated to 1964 or 1965. Additional potential triggers include two nearby small earthquakes in 1964 and 1965 (MW 3_9 and 3_2, respectively). The data for this study indicate that relatively large mass transports have become recurrent in Lake Biel following the deviation of the Aare River, thus modifying hazard frequency for the neighbouring communities and infrastructure. High-resolution bathymetry Lake sedimentology Mass-transport deposits River engineering Slope stability Subaquatic landfill Lake Biel Switzerland 21st century 19th century 20th century Lake dumping Jura water corrections Aare river Lake hazard Dewey 333.7-333.9 Dewey 550 Swiss National Science Foundation 200020‐146889 CH Swiss National Science Foundation 200021‐121666 CH 18 Institut des sciences de l'environnement 0DB 42 Département des sciences de la Terre 154 false 943 ISE Climat 944 ISE Eau 945 ISE Energie 938 ISE Pôle Sciences 946 ISE Villes et territoires 753 Limnology and Environmental Geology 664 Limnology and Geomicrobiology Sedimentology 67 2 93db5f59-2f4f-4a42-aab0-107b267e49b8 Article (Published version) Public article_Dubois_2020.pdf 6939830 application/pdf openAccess Centres et instituts / Institut des sciences de l'environnement Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département des sciences de la Terre

Title	Published in	Year	Views	Downloads

Subaquatic slope instabilities: the aftermath of river correction and artificial dumps in Lake Biel (Switzerland)	Sedimentology	2020	329	204
Lake Biel sediment record during the last 7500 years and impact of the Aare River deviation in 1878 AD		2012	420	10

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