JC2/C13 Cold Regions Cryosphere and Hydrosphere (IACS, IAHS/ICSIH, IAMAS, IPA)

Joint Inter-Association Symposium



23-Jun-2015, 15:00 - 16:30


 
Abstract content:

The separated effects of atmospheric forcing and changes in ice cover on runoff in the Ötztal catchment

Climate warming will alter the reservoirs snow and ice and consequently have an impact on the water balance of mountain regions. Glacierized catchments like in the Ötztal region (Tyrol, Austria) are particularly sensitive to changes in the cryosphere and the hydrological changes related to them. In this study the effects of changes in atmospheric forcing and the effects of changes in the glacierization of the Ötztal mountains on mean runoff and annual runoff maxima were investigated separately. The low-pass-filtered daily signal of changes in temperature and precipitation of the periods 2010-2039, 2040-2069 and 2070-2099 compared to the reference period 1985–2014 was added to the original meteorological measurements of 1986 to 2012. Scenarios of changes in glacier area distribution were calculated for the same periods based on observed volume changes and a modelled ice thickness distribution. Runoff was simulated using the hydrological model HQsim, which was calibrated for the runoff gauges at Brunau (890 km², 11 % glacierized), Obergurgl (72.5 km², 28 % glacierized) and Vent (165.4 km², 31 % glacierized). The climate forcing solely causes an increase in mean runoff from glacier melt in the summer months and a more concentrated occurrence of annual maximum runoff towards the days of highest glacier melt contribution. The reduction in glacier area in a constant climate would result in runoff reduction and an annual maximum runoff more pronounced at the start of melt season at high altitudes. The combination of climate forcing and glacier scenarios increases this effect to a more frequent occurrence of annual maximum runoff earlier in year.

 
Author(s):
K. Helfricht1,2, R.R. Wijngaard2, M. Huttenlau2, K. Schneider2.
1Institute of Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innsbruck, Austria.
2alpS, Centre for Climate Change Adaptation, Innsbruck, Austria.

 

Keywords:
climate warming     glacier change     runoff scenarios     annual maximum runoff     water balance     cryosphere     glacier inventory