Temperatures in two boreholes at Flüela Pass, Eastern Swiss Alps: the effect of snow redistribution on permafrost distribution patterns in high mountain areas

Abstract

Snow cover distribution strongly affects soil temperatures and, thus, plays a decisive role in determining permafrost distribution patterns. Redistribution of snow by avalanches and snow drift significantly affects the snow-melt pattern and soil temperatures in steep avalanche slopes of high mountain areas. At Flüela Pass, 2380 m a.s.l., eastern Swiss Alps, the presence and origin of permafrost that occurs at the base of an avalanche-affected slope below the regional lower limit of discontinuous permafrost was studied by field investigations and numerical simulations. Local permafrost distribution has been determined in former studies by applying geophysical methods and this was confirmed with two boreholes drilled at the slope base and in the avalanche starting zone. Temperature measurements confirm the presence of a 10 m thick permafrost body with temperatures close to the freezing point at the slope base. Numerical simulations of different snow-cover scenarios for 2002/03 demonstrate the particular effect on soil temperatures of high snow drift accompanying intense snow falls in early winter, controlling the duration of constant zero temperatures at the base of the snow pack at the beginning of the snow period.

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

“…These results are also in accordance with the pioneer work of Haeberli (1975) and the more recent studies carried out on other alpine periglacial talus slopes (e.g. Lerjen et al, 2003;Lütschg et al, 2004;Delaloye and Lambiel, 2005;Otto and Sass, 2006;Lambiel and Pieracci, 2008;Pieracci et al 2008;. Unfortunately, because no measurements could be made in the uppermost part of the study sites, it was not possible to determine if permafrost is present in the upper sections of the talus, as was observed by Lambiel and Pieracci (2008) in other sites.…”

“…Recent studies carried out in other regions of the Swiss Alps focused on the controlling factors and confirmed the heterogeneity of permafrost distribution in talus slopes (e.g. Lerjen et al, 2003;Lütschg et al, 2004;Delaloye and Lambiel, 2005;Lambiel, 2006;Lambiel and Pieracci, 2008;Pieracci et al, 2008;Phillips et al, 2009;. Due to the lack of in situ evidence, there is, nevertheless, a paucity of studies focusing on the stratigraphy of periglacial talus slopes (e.g.…”

“…Vonder Mühll, 1996;Haeberli et al, 2006), talus slopes (e.g. Delaloye, 2004;Lütschg et al, 2004), frozen moraines (e.g. Lambiel, 2006) and bedrock (e.g.…”

“…Francou, 1988;van Steijn et al, 2002;Sass, 2006), but little research has focused on the permafrost distribution and stratigraphy within talus slopes (e.g. Lütschg et al, 2004;Lambiel and Pieracci, 2008;Phillips et al, 2009) or on the palaeoclimatic significance of their ice content (e.g. Francou, 1977;Berthling et al, 2000).…”

“…However, due to the restricted drilling possibilities, only a few studies have focused on the verification of geophysical models of the permafrost distribution by direct in situ measurements and observations at depth (e.g. Phillips, 2000;Delaloye, 2004;Lütschg et al, 2004).…”