Canton du Valais, Service des forêts et du paysage (SFP), section des dangers naturels Kanton Graubünden, Amt für Wald Graubünden, Naturgefahren

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Eleanore Singleton
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1 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

2 "Toward better decision tools for the management of frequent avalanches: an introduction" Be$y Sovilla 1 Walter Steinkogler 1,2, Jochen Vei9nger 1,3, Michael Lehning 1,2, Ross Purves 3, 1 WSL- Ins)tut für Schnee- und Lawinenforschung SLF 2 CRYOS, Faculté de L environnement naturel, architectural et construit, EPFL, Lausanne 3 Geographisches Ins)tut, Universität Zürich WSL Institute for Snow and Avalanche Research SLF

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

4 Frequent avalanches Exemple 2 Exemple 1 Avalanche site Valleé de la Sionne, Switzerland 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

5 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)?

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

7 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.

8 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).

9 Snow cover characterization Simulations with SNOWPACK 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

10 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

11 Avalanche flow regimes and transitions The GEODAR 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 It can map hidden fronts, surges and transitions from dry to wet avalanche flow

12 (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., under review.

13 Modelling avalanche dynamics RAMMS avalanches

14 Modelling avalanche dynamics RAMMS entrainment Different κ-values were chosen to simulate frontal and basal erosion Frontal erosion Basal erosion

15 Modelling avalanche dynamics RAMMS temperature (Vera et. al., Thermal temperature in avalanche ﬂow; ISSW 2012)

16 The present and the future 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...

LINKING SNOW COVER PROPERTIES AND AVALANCHE DYNAMICS

LINKING SNOW COVER PROPERTIES AND AVALANCHE DYNAMICS Walter Steinkogler 1,2, Betty Sovilla 1 and Michael Lehning 1,2 1 WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland 2 CRYOS,