Quantification of basal friction for technical and silvicultural glide-snow avalanche mitigation measures

Feistl, Thomas; Bebi, Peter; Dreier, Lisa; Hanewinkel, Marc; Bartelt, Perry

doi:10.5194/nhess-14-2921-2014

Cited by 29 publications

(17 citation statements)

References 8 publications

(17 reference statements)

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“…The differences in inclination and vegetation between the sites might also explain why in March 2014 the combination of a snowfall followed by an increase in air temperature produced a glide avalanche only in Pista Nera and not in Sant'Anna. However, despite some differences between the two sites, they both belong to classes which present a low basal friction, favourable for snow gliding (Feistl et al, 2014).…”

Section: Predisposing Factor For Glide Avalanche Eventsmentioning

confidence: 94%

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

Maggioni

Godone

Frigo

et al. 2019

Nat. Hazards Earth Syst. Sci.

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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.

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Section: Predisposing Factor For Glide Avalanche Eventsmentioning

confidence: 94%

“…Moreover, after specific gliding events, we performed ad hoc snow surveys at the study sites. Observations were performed according to Fierz et al (2009).…”

Section: Data Collectionmentioning

confidence: 99%

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

Maggioni

Godone

Frigo

et al. 2019

Nat. Hazards Earth Syst. Sci.

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“…10a). In winter they are pressed down to the ground by the snowpack but form a snow-free layer at the bottom of the snowpack which can have a depth of a few centimeters to decimeters (Feistl et al, 2014). This leads to a systematic underestimation of HS mapped with photogrammetry (snow-free DSM is too high) as well as a systematic overestimation of HS measured manually with the avalanche probe because the probe penetrates the snowfree bottom layer and sometimes even the first layers of the ground.…”

Section: Underlying Vegetationmentioning

confidence: 99%

Mapping snow depth in alpine terrain with unmanned aerial systems (UASs): potential and limitations

Bühler¹,

et al. 2016

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Abstract. Detailed information on the spatiotemporal snow depth distribution is a crucial input for numerous applications in hydrology, climatology, ecology and avalanche research. Today, snow depth distribution is usually estimated by combining point measurements from weather stations or observers in the field with spatial interpolation algorithms. However, even a dense measurement network like the one in Switzerland, with more than one measurement station per 10 km2 on average, is not able to capture the large spatial variability of snow depth present in alpine terrain.Remote sensing methods, such as laser scanning or digital photogrammetry, have recently been successfully applied to map snow depth variability at local and regional scales. However, in most countries such data acquisition is costly if manned airplanes are involved. The effectiveness of ground-based measurements on the other hand is often hindered by occlusions, due to the complex terrain or acute viewing angles. In this paper, we investigate the application of unmanned aerial systems (UASs), in combination with structure-from-motion photogrammetry, to map snow depth distribution. Compared to manual measurements, such systems are relatively cost-effective and can be applied very flexibly to cover terrain not accessible from the ground. In this study, we map snow depth at two different locations: (a) a sheltered location at the bottom of the Flüela valley (1900 m a.s.l.) and (b) an exposed location on a peak (2500 m a.s.l.) in the ski resort Jakobshorn, both in the vicinity of Davos, Switzerland. At the first test site, we monitor the ablation on three different dates. We validate the photogrammetric snow depth maps using simultaneously acquired manual snow depth measurements. The resulting snow depth values have a root mean square error (RMSE) of less than 0.07 to 0.15 m on meadows and rocks and a RMSE of less than 0.30 m on sections covered by bushes or tall grass, compared to manual probe measurements. This new measurement technology opens the door for efficient, flexible, repeatable and cost-effective snow depth monitoring over areas of several hectares for various applications, if the national and regional regulations permit the application of UASs.

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“…The first (we term it "creep pressure model", CPM) is based on the Swiss guidelines on avalanche protection measures (Margreth, 2007) and the report of the European commission (Johannesson et al, 2009). The second method (we term it "sliding block model", SBM) was used to investigate the formation of glide snow avalanches, based on the failure of the stauchwall (Bartelt et al, 2012a;Feistl et al, 2014a). In this model the stauchwall is replaced by the tree.…”

Section: Four Avalanche Flow Regimesmentioning

confidence: 99%

Forest damage and snow avalanche flow regime

Feistl

Bebi²,

Christen³

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Snow avalanches break, uproot and overturn trees causing damage to forests. The extent of forest damage provides useful information on avalanche frequency and intensity. However, impact forces depend on avalanche flow regime. In this paper, we define avalanche loading cases representing four different avalanche flow regimes: powder, intermittent, dry and wet. Using a numerical model that simulates both powder and wet snow avalanches, we study documented events with forest damage. First we show that in the powder regime, although the applied impact pressures can be small, large bending moments in the tree stem can be produced due to the torque action of the blast. The impact area of the blast extends over the entire tree crown. We find that, powder clouds with velocities over 20 m s −1 can break tree stems. Second we demonstrate that intermittent granular loadings are equivalent to low-density uniform dry snow loadings under the assumption of homogeneous particle distributions. The intermittent regime seldom controls tree breakage. Third we calculate quasi-static pressures of wet snow avalanches and show that they can be much higher than pressures calculated using dynamic pressure formulas. Wet snow pressure depends both on avalanche volume and terrain features upstream of the tree.

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Quantification of basal friction for technical and silvicultural glide-snow avalanche mitigation measures

Cited by 29 publications

References 8 publications

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

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

Mapping snow depth in alpine terrain with unmanned aerial systems (UASs): potential and limitations

Forest damage and snow avalanche flow regime

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