Glaciermelt of a small basin contributing to runoff under the extreme climate conditions in the summer of 2003

✍ Scribed by Gernot R. Koboltschnig; Wolfgang Schöner; Hubert Holzmann; Massimiliano Zappa

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 332 KB
• Volume: 23
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.7203

✦ Synopsis

Abstract

This paper gives an overview on the regional hydrological impact of the heatwave, which affected Europe in the summer of 2003. We investigated the small, glacierized Goldbergkees basin in the Austrian Alps, which is situated directly beneath the high Alpine Sonnblick observatory (3106 m a.s.l.). We analysed the long‐term air temperature time series and quantified the extreme anomaly of the mean summer (JJA) air temperature for 4·4 times the standard deviation of the long‐term mean (1886–2000). The mean summer air temperature was 4·7 °C. In 2003, the solid fraction of precipitation was only 35%. This was the lowest value observed from 1927 to 2005. To quantify the impact of the warm temperatures on the Goldbergkees glacier positive degree‐day sums were calculated. The ‘hot’ conditions of the summer of 2003 rapidly melted the snow covering the glacier and finally melted the ice beneath. The winter balance of the Goldbergkees did not show anomalies. The specific net balance of Goldbergkees was − 1·8 m water equivalent (w.e.) for the 2002/2003 period and has been the most negative observed. Snowmelt was accelerated by low albedo, which was a result of Sahara dust‐falls. The hydrological response unit (HRU)‐based model PREVAH was applied to simulate hourly runoff, which was observed at the outlet of this small and topographically heterogeneous basin. All components contributing to runoff were separated. The model was driven using hourly meteorological data gained from the Sonnblick observatory. Snow‐ and icemelt were modelled based on an advanced temperature index‐based approach. The model was validated using observed glacier mass balance data. The maximum simulated icemelt rate was 2·7 mm/h (4·9 mm/h assigned to the glacier surface). During August 2003, glaciermelt contributed 81% to the total runoff. Copyright © 2008 John Wiley & Sons, Ltd.