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 ….