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

Abstract

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 4Ð4 times the standard deviation of the long-term mean . The mean summer air temperature was 4Ð7°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 1Ð8 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 2Ð7 mm/h (4Ð9 mm/h assigned to the glacier surface). During August 2003, glaciermelt contributed 81% to the total runoff.

Hydrological drought types in cold climates: quantitative analysis of causing factors and qualitative survey of impacts

“…The opposite, however, is investigated often: snowmelt floods, for example the Pacific Northwest flood of 1996 (Marks et al, 1998), and record glaciermelt in warm summers, for example in 2003 in Europe (Paul et al, 2005;Koboltschnig et al, 2009).…”

Evaluating the effect of snow and ice melt in an Alpine headwater catchment and further downstream in the River Rhine

“…As both basins are fed by the same quantity of water contribution from glaciers, the impact of glacier meltwater is still clearly recognizable at Andernach. The contribution of glaciers to August runoff in 2003 was particularly pronounced (see also Koboltschnig et al 2009). This is attributed to two factors: (a) strongly below-average streamflow runoff in non-glacierized catchments (Table 4), due to little precipitation and high evapotranspiration, and (b) an almost doubled rate of glacier storage change.…”

Linking ICT and society in early warning and adaptation to hydrological extremes in mountains

“…Resulting shifts in the frequency, magnitude and length of high-and low flow, including floods and droughts as well as seasonal shifts in overall discharge, are occurring in mountain chains worldwide (IPCC, 2012). Those regions that have experienced a longer growing season and a shift from snow to rain in the last few decades will react with earlier spring runoff and a lower runoff ratio (discharge/precipitation), (Botter et al, 2010;EEA 2009b;de Jong et al, 2009;Hunsaker et al, 2012;Koboltschnig et al, 2009;Lapp et al, 2005;Yilmaz and Imteaz, 2011).…”

“…Once snowmelt has terminated in early summer, smaller rivers (with catchments of < 5 km 2 ) are predicted to develop very low flow from the beginning of July onwards. They are projected to run completely dry during the summer months from mid-August to beginning of September once mountain glaciers have disappeared or decayed to a size where they are no longer influential on the discharge regime (Koboltschnig et al, 2009). Thus glacierfed summer discharge is expected to become very vulnerable in future decades, assuming that summer precipitation from rainfall is negligible and that storage from glaciers is reduced or absent.…”