Canton du Valais, Service des forêts et du paysage (SFP), section des dangers naturels

Kanton Graubünden, Amt für Wald Graubünden, Naturgefahren

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

http://www.progettostrada.net/

WSL Institute for Snow and Avalanche Research SLF

"Toward better decision tools for the management of frequent avalanches:

an introduction"  Be$y  Sovilla1  

Walter  Steinkogler1,2,  Jochen  Vei9nger1,3,  Michael  Lehning1,2,  Ross  Purves3,    1WSL-­‐Ins)tut  für  Schnee-­‐  und  Lawinenforschung  SLF  

2CRYOS,  Faculté  de  L’environnement  naturel,  architectural  et  construit  ,  EPFL,  Lausanne  3Geographisches  Ins)tut,    Universität  Zürich  

Frequent avalanches

Avalanche safety personnel often face the problem of whether to close a road, train or a ski slope. Those decisions are often very difficult to make, as they demand forecasting of meteorological conditions and corresponding snow cover characteristics as well as their influence on avalanche dynamics and prospective run-out distances.

Photo: P. Caviezel, TBA GR. Lawine Val Raschitsch überfliesst die Engadinerstrasse (2002)

Frequent avalanches

Exemple  1   Exemple  2  

To predict volume and the runout of a frequent avalanche it is important to understand how snow influences position and extension of the release zone as well as the avalanche dynamics

Avalanche site Valleé de la Sionne, Switzerland

Frequent avalanches

Exemple  1   Exemple  2  

There are many possible release areas at the VDLS test site. Why this location and this extension? How the snow in the release and along the path has influenced the flow dynamics (powder, dense, wet flows regimes and runout distances)?

Extreme avalanches Present avalanche mitigation methods are mainly dedicated to extreme avalanches. Traditionally, these methods do not directly associate snow cover properties with avalanche dynamics.          

   

 

As a result, no specific decision making tools exist for frequent avalanches. The STRADA project was founded in 2010 to fill this gap.

Ramms, Christen et all. 2006

New survey methods and models

   

In  the  last  years,  there  have  been  a  rapid  increase  in  both  survey  techniques  and  modelling  capabili<es  in  the  field  of  snow  and  avalanches.    These  improvements  allow  to  link  two  research  fields  which  were  tradi<onally  disjoined.      

Snow cover characterization airborne/ terrestrial laser scanning

Laser  scanning,  performed  before  and  aDer  an  avalanche    release,  allows  to  reconstruct  snow  depth  distribu<on,  loca<on  and  extension  of  release  zones,  and  the  avalanche  mass  balance  (i.e  quan<fy  erosion  and  deposi<on  along  the  path).    

SNOWPACK: it simulates the snow cover structure by using input data from weather stations

•  Air temperature •  Humidity •  Wind speed •  Short wave

radiation •  Long wave radiation •  Snow surface

temperature •  Snow height •  Ground temperature

 Lehning et al., Cold Regions and Technology, 1999

Snow cover characterization Simulations with SNOWPACK

Snow cover characterization Simulations with ALPINE3D

ALPINE3D: It  spa<ally  interpolates  data  from  weather  sta<ons  and  it    virtually  allows  to  reconstruct  snow  cover  stra<graphy  with  SNOWPACK  with  high  spa<al  resolu<on    

•  The GEODAR is a FMCW (Frequency Modulated Continuous Wave) phased array radar. The system penetrates the powder cloud and directly images the dense core with a resolution of around 1 m at 50 Hz over the entire slope.

•  Developed by a consortium of English universities (Cambridge, College London and Sheffield) and installed at the Vallée de la Sionne

Avalanche flow regimes and transitions The GEODAR

•  It can map hidden fronts, surges and transitions from dry to wet avalanche flow

(a)  

Vriend N. M., J. N. McElwaine, B. Sovilla, C. J. Keylock, M. Ash, and P. V. Brennan. High resolution radar measurements of snow avalanches. Geophys. Res. Lett., 2012. under review.

Modelling avalanche dynamics RAMMS avalanches

Frontal  erosion     Basal  erosion    

Different κ-values were chosen to simulate frontal and basal erosion

Modelling avalanche dynamics RAMMS entrainment

Modelling avalanche dynamics RAMMS temperature

 (Vera  et.  al.,  Thermal  temperature  in  avalanche  flow;  ISSW  2012)    

•  New technologies and tools are still to complex for a direct practical application. In the future it should be easier

•  Process understanding is directly applicable to all days situations already now…

We are here to discuss how ............

The present and the future