Vermessung und Eisdynamik des Vernagtferners, ?tztaler Alpen

摘要

Already in the 19~(th) century the first topographic map of Vernagtferner was produced by Sebastian Finsterwalder. This map forms the foundation for future surveys of the glacier geometry until today. Apart from eleven topographic surveys between 1889 and 2009 ice thickness measurements were carried out in the years 1966, 1967, 1979, 1983 and 2007 by seismic and electromagnetic methods, resulting in a detailed model of the subglacial bed. The combination of these data is now used as the basis for the analysis of area and volume changes of Vernagtferner between 1889 and 2009. During this period Vernagtferner lost 33 % of its area and 65 % of its volume Apart from the calculation of the geodetic mass balance for the individual periods, also the changes in defined altitude zones can be investigated. The results of this analysis enable the characterization of the glacier dynamics. The highest regionsofthe glacier and the glacier tongue increased their thickness during the first period 1889 until 1912 for example, while the intermediate region between 2800 m and 3250 m elevation showed a thickness reduction. The results demonstrate the connection between changes in the mass balance and the dynamic reactions which can only be investigated by an appropriate ice dynamic model. The application of a simple numerical model demonstrates the strong connection between ice dynamics and the glacier geometry, documenting the transient nature of the geometry observations at Vernagtferner.