Datenanalyse und Modellierungen konzeptioneller Art zur empirischen Bestimmung der Wasserbilanz im Einzugsgebiet des Vernagtferners für die Jahre 1895 bis 2011

摘要

The determination of the water balance of glacierized basins over long periods of time is a challenging task. The components precipitation, runoff, storage change of glaciers and snow as well as evaporation can be measured only rudimentarily. Measurements, however, are an indispensable basis for the development and application of models that calculate the water balance terms. Here, the conceptual hydrological model HBV3-ETH9 is applied in the basin of Vernagtferner, located in the Oetztal Alps, Austria, using as input daily values of air temperature and precipitation. The annual water balance terms are calculated over a period of over 100 years, thus describing the relationship between climate and glacier mass balance in a quantitative way. Calibration of model parameters for the period of 1980 to 2011 was achieved by using detailed measurements of runoff and glacier mass balance of Vernagtferner. For the period between 1895 and 1980 geodetic mass balances were used to calibrate the snow and glacier melt model parameters, while the remaining model parameters were kept unchanged. The results achieved are plausible for the most part of the investigation period. There are two phases, however, that experienced drastic changes of the glacier topography, i. e. the surge-type advance around 1900, and the extreme melt phase during 1938 and 1954. Here, the rapid areal changes of the glacier tongue need to be taken into account for improved calculations.