Reactions of a calving glacier to large changes in water level

Abstract

Austdalsvatn in western Norway was regulated in 1988 as a reservoir for a hydropower development. From a pre-1988 water level of 1157 m a.s.l. the new water level will vary more or less annually from 1170 to 1200 m a.s.l. The outlet glacier Austdalsbreen calves into this reservoir. About 1600 m up-valley from its terminus the glacier flows over a bedrock riegel that is, at its lowest point, ~15 m above the projected maximum lake level of 1200 m. As a result of the increase in water level, the surface velocity near the front has increased from about 0.07 to 0.13 m d-1. Calculations suggest that the glacier terminus will retreat about 750 m in 50 yrs. The measured response of the glacier terminus for the first three years is in good agreement with the simulations. -Authors