Toward better decision tools for the management of frequent snow avalanches

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Cori Griffin
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tools for the management of frequent snow avalanches Jochen Veitinger, Walter

1 Natural risk management in a changing climate: Experiences in Adaptation Strategies from some European Projects December 14th, 2011 Toward better decision tools for the management of frequent snow avalanches Jochen Veitinger, Walter Steinkogler, Betty Sovilla WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland

2 Project overview Interreg Project Italy- Switzerland, STRADA Action 4: Analysis of small to medium sized avalanches Involved Partners: Coordination: Regione Autonoma Valle d Aosta Dipartimento difesa del suolo e risorse idriche. Partcipants: Regione Lombardia Direzione Generale Protezione Civile, Prevenzione e Polizia locale; ARPA Lombardia Regione Piemonte Agenzia Regionale per la Protezione dell Ambiente; Cantone dei Grigioni - Ufficio forestale dei Grigioni, Sezione pericoli naturali; Cantone del Vallese - Service des forêts et du paysage (SFP), section des dangers naturels

3 Climate change and avalanches Structure and distribution of the snow cover determines the probability of avalanche releases, their extension and their dynamics Structure and distribution of the snow cover are influenced by meteorological paramters like temperature, wind speed and direction as well as frequency and intensity of the precipitations. Climate changes which influence climatic paramters like intensity and frequency of precipiation events, and /or the principal wind regime can influence the formation, dynamics and the frequency of avalanches

4 Frequent avalanche management today Today, frequent avalanches create substantial damage, because of increasing human activity in the alps (transport, tourism) - Road and railways - Ski resorts (ski slopes, tourist pathes, ) Importance of frequent avalanches for hazard mapping (e.g. avalanches with return periods of 30 and 300 years are considered in Switzerland) Decision tools for the management of frequent snow avalanches do not exist

5 Frequent avalanche management today

.) Output: snow depth distribution, stability Modelling

6 New tool for frequent avalanche management Snow cover Snow cover - avalanche scenarios: Avalanche dynamics Integration 3D - Modelling of snow cover: e.g. Alpine 3D, snowpack Input: meteorological parameters (wind, precipitations, temperature,..) Output: snow depth distribution, stability Modelling of avalanche dynamics: e.g. RAMMS Input: DTM, Release areas, friction parameters Output : run-out, flow-height, pressure

7 New tool for frequent avalanche management Todays avalanche dynamic models are designed for extreme avalanches Input parameters (e.g. release areas) are not derived from real snow parameters. Key Questions: New methods and parameters for releases areas of frequent avalanches including snow cover properties Effect of snow cover on avalanche runout

8 New tool for frequent avalanche management New Data: New measurement technologies, e.g. Laserscanning Snow depth distribution Location, extent and volume of avalanche release areas and run-out Snow cover before avalanche Snow cover after avalanche

9 Experimental : Fieldsites - Davos (Steintälli) - Wallis (Vallée de la Sionne) Practical oriented : - Graubünden (Sedrun) - Wallis (Liddes) - Aosta (Gressoney) - Lombardia (Aprica) - Piemonte (Macugnaga) Adapted from

10 Davos: Fieldsites: Example Laserscanning 2 IMIS stations + profiles, pictures, 5 Sensorscope stations 2 Automatic cameras

11 Release areas: new methods and parameters Slab: thickness homogeneity surface bed Snow cover Terrain: slope aspect roughness

12 Release areas: Roughness Ruggedness (Sappington, 2007): Incorporates both aspect and gradient component of slope Measured ruggedness does not correlate with slope

13 Release areas: Roughness Example Vallée de la Sionne: Terrain roughness Snow cover roughness

14 Release areas - Preliminary results Roughness and avalanche size: Slab thickness and avalanche size: Decrease of roughness with increasing avalanche size Smoothing of terrain by the snow Increase of slab homogeneity with increasing avalanche size

2003, red) reaches beginning of run-out zone (blue bar) with much more energy!

15 Effect of snow cover on avalanche runout Similar release conditions but different energy balance due to entrainment of snow Example: Avalanche which entrains more snow ( , red) reaches beginning of run-out zone (blue bar) with much more energy! Snow available for potential entrainment and snow cover quality (new snow, crust, wet, etc.) is important! (Sovilla, 2006)

16 Summary and Outlook Release Area Algorithm Weather & Avalanche Scenarios Parameterisation (type, dimension, entrainment) RAMMS Thematic maps (e.g. 3-year returnperiod map)

e Polizia Locale Arpa Piemonte, Agenzia Regionale per la Protezione Ambientale Cantone Grigioni, Amt für

17 Partner: Regione Valle d Aosta, Dipartimento Difesa del Suolo e Risorse Idriche Regione Lombardia, Agenzia Regionale per la Protezione dell Ambiente Arpa Lombardia, Direzione Generale Protezione Civile, Prevenzione e Polizia Locale Arpa Piemonte, Agenzia Regionale per la Protezione Ambientale Cantone Grigioni, Amt für Wald Graubünden, Naturgefahren Cantone Vallese, Service des forêts et du paysage (SFP), section des dangers naturels

Avalanche mitigation study: Behrends Avenue avalanche path and White Subdivision avalanche path, Juneau, Alaska

Avalanche mitigation study: Behrends Avenue avalanche path and White Subdivision avalanche path, Juneau, Alaska WSL-Institut für Schnee- und Lawinenforschung SLF WSL Institut pour l'étude de la neige et des avalanches SLF WSL Istituto per lo studio della neve e delle valanghe SLF WSL Institute for Snow and Avalanche