Forecasting the Effects of a Planned Reservoir which will Partially Flood the Tongue of Unteraargletscher in Switzerland

Abstract

In order to improve their hydro-electric power production in the Grimsel area, Kraftwerke Oberhasli (K WO) plan to construct a new reservoir with a storage leve l about 110 m high er than th e existing Grimselsee. This paper deals with the expected changes of Unteraargletscher after periodical contact with the resulting water body . Upon initial flooding, the lowe rmost section of Unteraargletscher, about 800 m long, will float , drift away, and melt. A rough estimate of the heat balance shows that the energy input into the lake would be sufficient to melt this ice within 2-3 years, so that calving and me lting will continue at a frontal ice cliff. The main effort of the study was aimed at forecas ting this retrea t. A pre-ex isting se ismic s urve y was supplemented by new so undings by radar and se ismic refl ec tion , resulting in re liabl e cross-sections and information about the sub-bottom material. The forecast is based on the existing mass flux and an empirica l calving rate relationship with water depth and predicts an equilibrium pos ition of the terminus so me 3-4 km further back than today, and a gain of water storage volume of 50 x 10 6 m 3 after 10 years.

Application of a minimal glacier model to Hansbreen, Svalbard

“…Parameterising the calving flux in this way has been suggested by, among others, Brown et al (1982), Funk and Röthlisberger (1989), Pelto and Warren (1991), Björnsson et al (2000). In recent years more comprehensive calving theories have been developed, looking at the interplay of different physical mechanisms and stressing the important role of crevasse formation and the type of sliding (for a comprehensive review, see Benn et al, 2007).…”

Dynamic Features of Thinning and Retreating Glaciar Upsala, a Lacustrine Calving Glacier in Southern Patagonia

“…A similar form of linear relation has been widely applied to many other tidewater or freshwater calving glaciers (e.g., Funk and Rothlisberger, 1989;Pelto and Warren, 1991;Warren et al, 1995b). These calving equations seem to exhibit well the behaviors of tidewater glaciers: when the terminus of a glacier retreats into deeper water from the moraine shoal or the bed rise, the rate of calving inwhere L is the width averaged tertninus position, Ui is the widthand depth-averaged ice velocity at the terminus, and Uc is the calving rate defined as the volume rate of iceberg discharge divided by the cross-sectional area of the terminus.…”

Implications of climate change on Glacier de la Plaine Morte, Switzerland

“…An important factor that needs to be accounted for in this evaluation is the effect of lake water on local ice surface elevation change. An increase in ice flow speed and calving rate triggering a subsidence of the glacier surface has been reported for glaciers in contact with freshwater lakes (Funk and Röthlisberger, 1989;Tsutaki et al, 2011). This factor is not included in the modelled glacier retreat using GERM and needs to be added.…”