Glacier-dammed lake outburst events of Gornersee, Switzerland

Abstract

Gornersee, Switzerland, is an ice-marginal lake, which drains almost every year, subglacially, within a few days. We present an analysis of the lake outburst events between 1950 and 2005, as well as results of detailed field investigations related to the lake drainage in 2004 and 2005. The latter include measurements of lake geometry, water pressure in nearby boreholes and glacier surface motion. A distributed temperature-index melt model coupled to a linear-reservoir runoff model is used to calculate hourly discharge from the catchment of Gornergletscher in order to distinguish between the melt/precipitation component and the outburst component of the discharge hydrograph. In this way, drainage volume and timing are determined. From 1950 there is a clear trend for the outburst flood to occur earlier in the melt season, but there is no trend in lake discharge volumes. Peak discharges from the lake lie significantly below the values obtained using the empirical relation proposed by Clague and Mathews (1973). The shapes of the 2004 and 2005 lake outflow hydrographs differ substantially, suggesting different drainage mechanisms. From water balance considerations we infer a leakage of the glacier-dammed lake in 2005, starting 1 week prior to the lake outburst. During the drainage events, up to half of the lake water is temporarily stored in the glacial system, causing substantial uplift of the glacier surface.

Moment Tensor Inversions of Icequakes on Gornergletscher, Switzerland

“…In this article, we have not presented any moment tensors for these events. In the case of Gornergletscher, the geometry of the glacier bed (Huss et al, 2007; Fig. 1) requires that Green's functions for a 2D or 3D seismic velocity model have to be calculated.…”

“…The data used for the present analysis were acquired as part of an investigation of the yearly subglacial drainages of Gornersee, a nearby ice-marginal lake (e.g., Huss et al, 2007;Sugiyama et al, 2007;Walter et al, 2008). The instrumentation for the 2004 and 2006 seismic arrays consisted of 14 and 24 seismometers, respectively, most of which were installed at the glacier surface (Fig.…”

Mountains Under Climate and Global Change Conditions – Research Results in the Alps

“…After the last glacier-friendly period so far in the 1980s, which saw glacier advances, we can now observe an intensified retreat of Alpine glaciers. Related phenomena, such as the formation of supraand peri-glacial lakes require new strategies in glacier monitoring and trigger research on basic mechanisms (Huss et al, 2007). By studying long glaciological time series we obtain base lines for interpreting past climate in high mountain areas where only few direct recordings of weather stations are available (Fischer, 2010;Vincent et al, 2004).…”

Multilevel analysis of health risk behaviour in Czech teenagers

“…Ice-dammed lakes may react with greater delay as glacier dam uplift requires large amount of water causing sufficiently increased hydrostatic pressure (Glazirin 2010). However, Huss et al (2007) and Glazirin (2010) both indicate a shift of ice-dammed lakes drainage to earlier time within a year mainly in the second half of the 20th century. It means the diference between the two lake types would not probably be that large if only the latest data were included.…”