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Soil Erosion induced by snow avalanchesMichele Freppaz
The snow avalanche paths
Avalanche tracks contributelargely to the landscapecomplexity of the European Alps
They are preferred habitats for animal species and have uniquevegetation and soilcharacteristics (e.g. Rixen et al., 2007; Freppaz et al., 2010)
Sediment transport
When avalanches involve:a) the whole depth of snow and/orb) run onto snow-free areas
they may incorporate large amounts of soil, organic and rock debris
a) b)
Methods of estimation
Freppaz M., Godone G., Filippa G., Maggioni M., Lunardi S., Williams M.W., Zanini E. (2010) Soil Erosion Caused by Snow Avalanches: a Case Study in the Aosta Valley (NW Italy). Arctic, Antarctic, and Alpine Research, Vol. 42, No. 4: 412–421
Sampling on the avalanche depositusing a gridded design (n=105)
Snow was collected at differenttimes from the upper 10 cm of theavalanche deposit (coring device: 200mL)
The runout area: sediment amount and characteristics
The mass accumulation rate in the runoutzone ranged between 9.8 and 240.8 Mgha-1
Freppaz M., Godone G., Filippa G., Maggioni M., Lunardi S., Williams M.W., Zanini E. (2010) Soil Erosion Caused by Snow Avalanches: a Case Study in the Aosta Valley (NW Italy). Arctic, Antarctic, and Alpine Research, Vol. 42, No. 4: 412–421
Rocks (%) (>2mm)
Freppaz M., Godone G., Filippa G., Maggioni M., Lunardi S., Williams M.W., Zanini E. (2010) Soil Erosion Caused by Snow Avalanches: a Case Study in the Aosta Valley (NW Italy). Arctic, Antarctic, and Alpine Research, Vol. 42, No. 4: 412–421
The runout area: soil characteristics
distance of maximum avalanche runout
Further erosion in the deposits, with theremoval of the finer material and theaccumulation of rocks fragments.
Haplic Regosol
Confortola, G., Maggioni, M., Freppaz, M., Bocchiola, D. (2012) Modelling soil removal from snow avalanches: a case study in the Italian Alps. Cold Regions Science and Technology 70: 43-52, 2012.
Modelling soil removal from snow avalanches
An already developed 1-D avalanchedynamics model was modified to includesoil erosion
SOIL EROSION COULD OCCUR ALONG THE WHOLE TRACK
Glide avalanches
Avalanches which involve the whole depth of snow
Snow gliding
Glide cracks
Glide avalanches
February, 27 March, 1
Photo Renzino Cosson
Stanchi S., Freppaz M., Ceaglio E., Maggioni M., Meusburger K-. Alewell C., Zanini E. (2014) Soil erosion in an avalanche release site (Valle d’Aosta: Italy ): towards a winter factor for RUSLE in the Alps, Nat. Hazards Earth Syst. Sci., 14, 1761–1771
Among other factors (e.g. little surfaceroughness) it depends upon free water atthe ground (soil)-snow interface
The production of a thin mud layer under the snowpack could reduce the roughness and friction at the snow-soil interface
Glide avalanches release
Ceaglio E., Mitterer C., Maggioni M., Ferrraris S., Freppaz M. (2017) The role of soil volumetric liquid water content during snow gliding processes. ColdRegions Science and Technology 136: 17-29
Removal of the soil materialfrom the release zone (vegetation is entrapped by the snow and the soil isoverturned?)
Snow avalanche suppression by means of avalanche barriers significantly influences the soil properties
Glide avalanches: soil removal mechanisms
Grass rolls
