Salzach river discharge, Austrian Alps Cubic metres per second

100

20 40 60 80

0 October November

Cubic metres per second 100

2002

20 40 60 80

0 October November December Source: redrawn from Koboltschnig, et al., 2008.

Figure 7: Observed (dotted line) and simulated hydrograph (grey) at the gauging station Mittersill and contributing fraction of ice melt (blue) for the normal (1999–2000) and the extreme (2002–2003) period.

melt is calculated, the glacier melt contribution in this study consid- ers the entire firn/ice melt of glaciers, which can be above zero even in years with a positive glacier mass balance.

Simulated contributions of glacier melt (firn/ice melt) to annual total runoff were calculated between 1 and 4%. In the period 1999–2000, when the glacier mass balance of Goldbergkees and Stubacher Sonnblickkees have been observed to be zero or slightly above zero, the annual contribution of glacier melt was calculated as 1% (Fig. 7). The highest monthly contribution in 2000 was 4% for the month of August, and the highest daily glacier melt was 12% on 26 August 2000.

The exception was the outstanding hot and dry summer in 2003, when glaciers contributed 15% of the annual runoff and 58% to

the August runoff (Fig. 7). The maximum daily contribution was calculated as 69% for 13 August 2003. At that time the observed annual mass balance of the Goldbergkees was –1.8 m and at the Stubacher Sonnblickkees it was –2.87 m.

This study shows that the glacier melt contribution at one specific point along the basin drainage varies seasonally and from year to year depending on temperature and precipita- tion cycles. Due to the relatively small fraction of glacierized areas the contribution of glacier melt in the Upper Salzach catchment is normally quite small, but had a respectable in- fluence during the extraordinary hot and dry summer of 2003. Nevertheless the mean discharge during summer (JJA) 2003 was only 86% compared to the long term mean JJA discharge (1951 to 2006) and only 80% for August 2003.

23 January February March April May June July August September December January February March April Extreme period 2003 May June July August September 1999

Observed runoff Icemelt runoff contribution

Note: discharge measured at Mittersil station

Normal period 2000