competence center environment & sustainability of the eth domain tramm – triggering of rapid...
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Competence Center Environment & Sustainability of the ETH Domain
www.cces.ethz.ch
TRAMM – Triggering of Rapid Mass Movements in Steep Terrain
Manfred Stähli
WSL, Mountain Hydrology and Torrents
Rapid mass movements – ubiquitous and costly
Motivation
8 units of the ETH domain joining forces
WSL – Mountain Hydrology and Torrents
Hillslope Hydrology,
ETHZ – Soil and Terrestrial Environmental Physics
Soil Physics, Bioengineering
EPFL – Laboratory of Soil Mechanics
Soil Mechanics,
TRAMM partnership
WSL – Snow and Permafrost Research
Snow Physics WSL – Avalanche, Debris flows and Rock Fall
Fluid dynamics
ETHZ –Geotechnical Engineering
Soil Mechanics,
EPFL – Environmental Hydraulics Laboratory
Fluid dynamics, EPFL – Eng. and Env. Geology Laboratory
Hydrogeology
External partners: UNI Lausanne – Institute of Geophysics Geophysics,UNI Zürich – Department of Geography Hillslope hydrology
June 1, 2006; NG 4
Project approach• Exploit similarities of the three processes
• Develop concepts, models and technologies applicable to all of these rapid mass movements
• Perform common large-scale experiments
Project approach
Example of a technique applicable to different rapid mass movements
5
Acoustic sensors to capture precursors
Sensor development
Example of a model applicable to different rapid mass movements
Self-Organized Criticality Model
Fiber bundle model
Model development
Cohen et al. 2009. Water Resources Research
Field experiments
7
Field experiments
Wannengrat (Davos)Snow avalanche test site
Rüdlingen (SH)Artificial landslide triggering
Illgraben (Susten VS)Debris flow erosion
Rufiberg (Arth SZ)Hydrology of a hillslopeWiler (Lötschental VS)
Hydrology of a hillslope
The Rüdlingen experimentpresented by Sarah Springman (IGT ETHZ)
Main results and achievements of TRAMM
1. Disposition2. Precursors
3. Prediction
4. Vegetation
5. Transition
6. Flow
Spatial statistical models are useful for assessing the disposition of a slope to trigger shallow landslides.
Von Rütte et al., submitted to Geomorphology.
Analysis of landslide inventories (Rickli, WSL)
Model with only geomorphic parameters
Results / Achievements
(1) Disposition
Susceptibility map for a catchment in the Napf-regionbased on logistic regression.
black dots = observed shallow landslides
van Herwijnen and Schweizer, submitted to Journal of Glaciology.
Recognition of rapid mass movements with acoustic sensors is possible but not yet operational.
Potential to record precursors of avalanches and landslides was demonstrated.
Major problems: a) limited wave propagation; b) noise filtering
Seismic signals associated with the release of a natural snow slab avalanche.
Results / Achievements
(2) Precursors
A new geomechanical model accounting for spatially variable saturation was developed.
Results / Achievements
(3) Prediction
2-dimensional
finite element discretization
deformation = f(soil water content and pore pressure)
Localization of shear strains during infiltration (case study: Rüdlingen)
Nuth and Laloui, 2008, Computers and Geotechnics.
Root reinforcement was quantified and implemented in a landslide triggering model framework.
Results / Achievements
(4) Vegetation
Lab experiment: Pullout tests of single roots
Schwarz et al., 2010, Earth Surface Processes and Landform.
Schwarz et al., in press, Journal of Geophysical Research
Progressive failure of root bundles
Roots not only break, but also slip.
The progressive failure of a hillslope can be reproduced with a combination of SOC and fiber bundle model.
Results / Achievements
(5) Transition
Failure patterns simulated with SOC model.
Cohen et al., 2009, Water Resources Research
Lehmann et al. in prep. Water Resources Research
Combination of randomness and known hydro-mechanical controls.
Not a threshold phenomenon, but a propagation of a local failure
Berger et al., 2010, Water Resources Research
Berger et al., in press, Journal of Geophysical Research
Inner organization of moving avalanches or debris flows is important for run-out prediction.
Results / Achievements
(6) Flow
Front of an avalanching mass enlightened by a vertical laser sheet (laboratory EPFL).
Sediment entrainment of debris flows quantified.
Critical role of the solid concentration for the stability of flow motion
Erosion (red) and deposition (blue) areas of a debris flow (1 July 2008) in the Illgraben.
Monte Verità-conference (April 2010)
16
International exchange
Communication to Natural Hazard Experts in Switzerland (FAN) and local authorities
June 1, 2006; NG
Stakeholder dialog
Synthesis report
Dissemination
• Main achievements
• 2-page summary of sub-projects
• For natural hazard experts and decision makers
Acknowledgment
• The Competence Centre Environment and Sustainability (CCES) of the ETH Domain for financial support and promotion of the TRAMM project
• The Swiss National Foundation (SNF) for funding of grants No. 206021-117407 / 1 ( R’Equip) and 200021-122299 / 1 (Dissertation Jonas Von Rütte)
• Gemeinde Rüdlingen (Gemeindepräsidentin K. Leutenegger) für die Bewilligung und grosse Unterstützung bei der Durchführung des Hangrutsch-Experiments Rüdlingen und Gemeinde Buchberg für die Hilfe bei der Wassserversorgung
• (Burger-)Gemeinde Wiler (Lötschental, VS; Gemeindepräsident: B. Rieder) für die Bewilligung und Unterstützung bei der Durchführung des Hang-Experiments Wiler – Obre Wald.
• Forstdienst Wiler für Geländearbeiten und Bereitstellung eines Bewässerungssystems beim Hangexperiment Wiler – Obre Wald
• Unterallmeid-Korporation Arth (Herr K. Weber) und Herr Kenel (Rufiberg) für die Bewilligung und Unterstützung bei der Durchführung des Hangexperiments Rufiberg.
• FAN – Fachleute Naturgefahren Schweiz – für die Möglichkeit, Ergebnisse aus dem Projekt in der FAN-Agenda zu publizieren
• Geobrugg AG, Romanshorn, für die Bereitstellung eines Sicherheitsnetzes beim Rüdlingen-Experiment
• Centro Stefano Franscini and the staff of Monte Verita for hosting the TRAMM International Conference on Triggering of Rapid Mass Movements in Steep Terrain and providing a financial contribution.
The TRAMM consortium is grateful to ….