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

Margherita Maggioni,Danilo Godone,Michele Freppaz,Barbara Frigo

doi:10.5194/nhess-19-2667-2019

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.

Highlights

Snow gliding processes have recently gained importance among scientists as climate change might influence the snow cover and the related processes, leading to a reduction of dry snowpacks and an increase in wet ones (Castebrunet et al, 2014)
As WCR probes were mainly designed to measure volumetric liquid water content in soils, we were able to transform the values recorded by the instrument place in the basal snowpack layer following the corrections found by Godio et al (2018) during an experimental campaign carried out at the vicinity of the manual measuring site of Sant’Anna
We did not find any relationship between the glide rate and the soil volumetric liquid water content (VLWC) in the continuous cold gliding period in Pista Nera, as we have recently found at another experimental test site in the same region (Ceaglio et al, 2017)

Summary

Introduction

Snow gliding processes have recently gained importance among scientists as climate change might influence the snow cover and the related processes, leading to a reduction of dry snowpacks and an increase in wet ones (Castebrunet et al, 2014). The approach commonly used for studying snow gliding and glide-snow avalanches starts from the distinction between cold and warm temperature events (Clarke and McClung, 1999). This distinction is based on the origin of liquid water at the snow–soil interface: in a cold event, the nec-. The most recent studies by Ceaglio et al (2017) and Fromm et al (2018) underline the importance of soil moisture as a driving factor for snow gliding. Our goal is to quantify the linkages between soil water content and snow gliding processes and to assess the factors predisposing the glide avalanche release, under different meteorological and snowpack conditions (warm vs cold events)

Study area

Data collection

Data analysis

Predisposing factor for glide avalanche events

Predisposing factors for snow gliding

Conclusions