Snow gliding and glide-snow avalanches: recent outcomes from two experimental test sites in Aosta Valley (northwestern Italian Alps)

Abstract

Abstract. Snow gliding and glide-snow avalanches are gaining importance among scientists as global warming might induce conditions favourable to those phenomena. Our aim is to analyse such processes with a particular focus on the potential driving factors associated with the soil conditions. We equipped two experimental test sites in the Aosta Valley region (NW Italy) with glide-snow shoes, temperature and volumetric liquid water content (VLWC) sensors in the soil and in the basal snowpack layer; snow and weather parameters were also collected by automatic weather stations and at manual snow measuring sites. In the two monitoring seasons 2013–2014 and 2014–2015 we registered nine glide-snow avalanches, two cold and seven warm events, which were characterized by different snow and soil conditions. In the only warm glide-snow avalanche event, which presented a continuous gliding before, the daily glide rate showed a significant exponential relationship with the soil VLWC. We also found, though without a general trend, that gliding and non-gliding periods (either considering warm and cold periods separately or together) were characterized by significantly different predisposing factors. This study contributes to the assessment of the importance of soil VLWC, which seems to be one of the most important driving factors for gliding processes. Therefore, it supports the need, already suggested by other scientists, for analysing such processes with an interdisciplinary approach which integrates snow and soil sciences.

Characteristics and hazards of different snow avalanche types in a continental snow climate region in the Central Tianshan Mountains

“…Full-depth avalanches (FDAs and FWAs), where the entire snowpack is mobilized down to the ground, mainly occurred at the beginning and end of the snow season (Fig. 5), which was consistent with observations of other places in the Northern Hemisphere (Ma and Hu, 1990;Clarke and McClung, 1999;Dreier et al, 2016;Maggioni et al, 2019). Surface-layer avalanches (SDAs and SWAs) mainly occurred during the middle of the snow season and the transition from the middle to the end of the snow season in the region (Fig.…”

“…For the full-depth avalanches with different snow characteristics, the occurrence time and formation mechanisms of FDAs and FWAs varied significantly. Because of the pressure difference between the snow and soil, the snow at the bottom of the snowpack can absorb the water from the soil, which leads to an increase in the water content of the snow at the bottom of the snowpack, resulting in reduced friction at the snow-soil interface (Dreier et al, 2016;Ceaglio et al, 2017;Maggioni et al, 2019). Therefore, the increase in water content at the bottom of the snow due to geothermal and free water transport in the surface soil caused a decrease in snow-soil interface friction, which led to FDA release in the early snow season.…”

“…Full-depth avalanche releases have been summarized in previous reviewing publications (Höller, 2014;Ancey and Bain, 2015), which concluded that a full-depth avalanche originates from a failure at the snow-soil interface when it is wet so that the basal friction is reduced. It is agreed that the snow-soil interface becomes wet for the following reasons: warm ground temperatures stored in the ground before the snow season melt the lowermost snow layer (Höller, 2014;Ceaglio et al, 2017); a strong hydraulic pressure gradient causes the free water in the soil to move into the snow layer at the bottom of the snowpack (Ceaglio et al, 2017;Maggioni et al, 2019); and meltwater or rain percolates from the snow surface to the snow-soil interface (Conway and Raymond, 1993;Peitzsch et al, 2012;Höller, 2014).…”

Physical Modeling of Snow Gliding: A Case Study in the NW Italian Alps

“…The study area, located in Aosta Valley in the north-western Italian Alps, very close to the Mont Blanc Massif (4810 m asl), consists of an avalanche site called "Torrent des Marais-Mont de la Saxe", running on a west exposed slope, from 2115 m to 1250 m asl (Figure 1). The long-term yearly mean precipitation in the study area is 840 mm yr −1 (1995-2010), and the mean annual air temperature is +2.8 • C (1993-2010, data from the AWS Courmayeur-Mont de la Saxe at 2076 m asl of the Ufficio Centro Funzionale, Aosta Region, [24]). The average cumulative annual snowfall is 275 cm at 1250 m asl and about 450 cm at 2000 m asl [25].…”

Towards an Ensemble Machine Learning Model of Random Subspace Based Functional Tree Classifier for Snow Avalanche Susceptibility Mapping

“…Snow avalanche, as a natural disaster severely affects socio-economic and geomorphic processes through damaging ecosystems, vegetation, landscape, infrastructures, transportation networks, and human life [3], [4]. The recent frequency, irregularity, and uncertainty in the occurrence regime of avalanche had been strongly linked to climate change and global warming [5]- [8]. Therefore, an avalanche is fast becoming a significant risk in more nations [9]- [11].…”