Glaciological Investigations at Glacier du Giétro and Glacier de Corbassière

Tongue of Glacier du Giétro with monitoring installation (4.Sep.2003). (click to enlarge)

Seasonal flow velocity (click to enlarge)

Glacier de Corbassière (Foto G. Kappenberger, 2007)

Glacier de Corbassière with a length of 10.1 km and an area of 18.3 km² is one of the largest glacier in the Swiss alps. The steep tongue of Glacier de Giétro (4.5 km long, covering an area of about 6 km²) flows over cascades and ends today 500 m above the bottom of the main valley. During the general glacier maxima of the Little Ice Age at the end of the 16th and beginning of the 19th century, the glacier advanced over steep valley sides. The river in the main valley was occasionally dammed by accumulated ice blocks after break-offs. In 1595 and 1818 large water outbursts started catastrophic splash floods causing large damage down to the Rhone valley. Since the construction of the Mauvoisin reservoir in 1957 break-offs of large ice masses may cause an oversplash over the dam at times when the reservoir is nearly filled. The safety of the installation is of main interest and requires a continuous supervision.

The glaciers have been monitored intensively since the 1960's. Measurements of mass balance, flow movement, and volume changes document the general variations of the glaciers. Automatic observation systems have been developed in order to measure the surface displacement continuously and detect short-term changes of flow behaviour. The current system is based on motorized theodolite with integrated distance meter which detects and follows several targets automatically. A telemetric data transmission provides instantaneous data access.