Assessing Subaquatic Mass Movement Hazards: an Integrated Observational and Hydrodynamic Modelling Approach
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Assessing Subaquatic Mass Movement Hazards: an Integrated Observational and Hydrodynamic Modelling Approach Love Råman Vinnå 1,2 & Damien Bouffard 2 & Alfred Wüest 1,2 Stéphanie Girardclos 3,4 & Nathalie Dubois 5,6
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Received: 27 March 2020 / Accepted: 31 August 2020/ # The Author(s) 2020
Abstract
High-resolution lake and reservoir bathymetric surveys can pinpoint locations that may experience underwater landslides (subaquatic sedimentary mass movements). These can pose a risk to underwater and shoreline infrastructure. This paper outlines an approach for using spatial variation in sedimentary patterns to identify areas susceptible to subaquatic mass movements in lakes and reservoirs. This study focusses on Lake Biel (Switzerland), which has experienced a protracted history of upstream alteration of river flow. Altered flow patterns increase risk of unstable sedimentary features and subaquatic mass movements. Data from sediment traps and cores, Acoustic Doppler Current Profilers and results from a 3D hydrodynamic model gave a consistent picture of spatial and temporal variation in weather-related sedimentation. Erosion caused by short-term rain events contributes the largest proportion of sediments to the lake. Strong rain events combine with typical wind patterns to drive lake circulation. The net effect results in preferential sedimentation onto a steeply sloping shelf prone to subaquatic slides. The integrated approach outlined here incorporates short- and long-term sediment dynamics to provide a systematic assessment of lake sedimentation and potential mass movement hazards. This research represents a first step in developing a risk-evaluation tool for aquatic hazard evaluation. Keywords Subaquatic mass movements . Coastal infrastructure . Weather-dependent sedimentation . River redirection . Geological engineering . Risk evaluation tool
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11269-02002660-y) contains supplementary material, which is available to authorized users.
* Love Råman Vinnå [email protected] * Damien Bouffard [email protected] Extended author information available on the last page of the article
Vinnå L.R. et al.
1 Introduction Shorelines of both inland and coastal waters are often highly altered geomorphological environments that accommodate major infrastructure including harbours, roads, railways, underwater pipelines, transmission cables and water intakes. Slope failures resulting in massive, rapid downslope movement of sediment, also known as subaquatic mass movements, can damage this infrastructure and disrupt lake ecosystems. Coastal examples include the destruction of the entire dock area in the town of Valdes, Alaska (Coulter and Migliaccio 1966), a landfill collapse at an airport in Nice, France (Kopf et al. 2010) or the recent 2020 destruction of eight houses in Alta, Norway caught on camera (e.g. https://www.nytimes. com/2020/06/05/world/europe/norway-landslide.html). These events can damage submarine infrastruct
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