Second FORALPS Conference „Contributions for a wise management of water resources from meteorology and climatology“ Max Gandolf Bibliothek, Salzburg University, 28. 11. 2007

Runoff from high montain regions as affected by global change

Dr. Ludwig N. Braun Commission for Glaciology Bavarian Academy of Sciences, Munich

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Statement 1

Water yield from glacierized catchments is enhanced during dry and hot summers due to excessive ice melt, however, this compensating effect will be lost should the glaciers vanish

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Summer discharge 1998, tributaries to the River glaciated basin (Ötztaler Ache/Sölden, 375 km²)

May June July Aug. Sept. 100 m³/s

0 non-glaciated basin (Brixentaler Ache, 320 km²)

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 from: Hydrological Atlas of , 2001 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Thinning of the glacier, rock falls Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 GaugingGauging stationstation VernagtbachVernagtbach ,, AA == 11.411.4 kmkm ²²,, 26352635 mm a.s.la.s.l .. Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 firn area approx. 2/3 of glacier

firn area approx. 1/5 of glacier

bare ice 4/5 Discharge of Vernagtferner: increase in diurnal variations due to loss of firn areas Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 12.7.2003 14.30: Discharge Vernagtbach approx. 11 m 3/s Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Vernagtferner in the Ötztal Alps in Winter 2005/06

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Vernagtferner 1:10‘000

S. Finsterwalder 1889

First map of entire glacier based on terrestrial photogrammetry

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 1 m

Yearly height change of glaciers after 1889, Analyses started by R. Finsterwalder 1953 („Munich School“) Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Change of area and specific ice storage of Vernagtferner after 1844

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Reconstruction of yearly Vernagtferner mass balance 1889 - 2005 Using the HBV/ETH model (Ellenrieder, Weber, Cribellier) Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Reconstructed running 5-year means, basin „Gletscherthor“, A= 15 km² HBV/ETH model, Weber & Cribellier (2007) Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Statement 2

With further global warming the solid fraction of precipitation will diminish at all levels, and as a result, floods from high alpine areas will increase in frequency and magnitude.

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Influence of Global Change (Steinacker, 2005): Liquid portion of precipitation in % of total on Sonnblick mountain (3105 m, Austria): three-fold increase in the past 110 years

Quelle: Auer, I. R. Böhm, 2004: Der Sonnblick. ZAMG 5% 15%

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Heavy precipitation in summer:

Sourceregion humidity:

North Sea: 10 g/m 3 Atlantic (Brit. Ins.): 12 g/m 3 Continental Europe: 10-15 g/m 3 Mediterranian: 20-25 g/m 3

Important to consider: Fraction of solid precipitation (freezing level)

According to Steinacker (2005)

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Elevation (m) Air from the Mediterranean Hypsometric curve of the Ötztal 3500 Air from Central Europe

3000 Air from Atlantic Air from the North Sea 2500

2000

1500

1000

% 10 20 30 40 50 60 70 80 90 100

Level of snow fall in summer (Steinacker, 2005) Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 3800 Ötztal 1997/1969 Distribution Area 1997 Area 1969 3600 of glaciers in Zillertal 1999/1969 Area 1999 Area 1969 the Ötztal 3400 1969 & 1997 3200 1969

3000 and Zillertal 2800 1969 & 1999 Ötztal 1969 ∑ 179 km² Elevation bands(m) Elevation 1997 Ötztal 1997 ∑ 151 km² 2600 -16% Kuhn & 2400 Zillertal 1969 ∑ 66 km² Lambrecht Zillertal 1999 ∑ 51 km² 2006 2200 -23%

2000

0 4000 8000 12000 16000 20000 Area (*103 m2) Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Analysis of floods from high alpine regions

2 case studies in the Vernagtbach basin: 11.4 km 2, 2635 – 3633 m a.s.l., 80 % glacierized

•4 August 1998: Strong ice melt followed by heavy thunderstorm

• 22-24 August 2005: typical Genova-cyclone (Vb-Type), precipitation in the inner Ötztal quite low , no glacier melt

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 StormStorm cloudsclouds overover thethe glacier,glacier, Aug.1998Aug.1998 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Gauging station Vernagtbach 4 Aug. 1998 19.00 o‘clock Q = 19 m³/s Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Pegelstation Vernagtbach am 4. August 1998 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Lessons to be learned from the event on 4 Aug. 1998:

Localized storm in addition to strong melt may cause heavy floods from glaciers, but due to the limited area of the storm there is practically no damage further downstream

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Flooding of Horlachbach b. Umhausen 23.8.05 Precipitation on 22 & 23 Aug. 2005 in Ötz: ca. 70 mm Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 The Stuiben Water Falls near Umhausen On 23 Aug. 2005 at 16.00 o‘clock

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 flooding of the road between Umhausen and Tumpen Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Inn River at Innsbruck on 23 August 2005 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Discharge at gauging station Vernagtbach 2005

No ice melt previous to the precipitation event of 20 – 23 August 2005, and snow fall at high elevations prevented flooding of Innsbruck

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Snowfall on Vernagtferner on 21 Aug. 2005 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Climate scenarios

Control 1961-1990

Scenario 2071-2100

Schär et al. (2004) Temp change chang in T variability Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Change in the seasonal distribution of precipitation Swiss Alps (after Beniston, 2007 )

7 2071-2100 6

5 1961-1990 4

3

2 Mean daily sum [mm] +25% +5% -25% -10% 1 Winter Spring Summer Autumn 0 1 31 61 91 121 151 181 211 241 271 301 331 361 Day of the year

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Change in seasonal discharge (Swiss Alps, after Beniston, 2007 )

less Less Snow melt Ice melt 6 Winter Spring Summer Fall 5 +90% -5% -45% -20%

4

3 2071-2100 2 1961-1990 1 . Mean daily runoff depth [mm]

0 1 31 61 91 121 151 181 211 241 271 301 331 361 Julian day

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 GLOWA- Precip., snow fraction snow depth : development 25 % 2000-2035 in lowlands 15 % München, 500m

Ötztal Alps , 80 % 2600 m a.s.l. 60 %

Vernagtferner Ötztal, 3200 m 90 % 80 % Weber (2006)

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Modelling the future of Vernagtferner (Weber, 2007)

2000

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Modellierung Zukunft Vernagtferner (Weber, 2007)

2000 + 10 x 2003 (2010 )

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 2000 + 15 x 2003 (2015 )

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 2000 + 20 x 2003 (2020 )

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 2000 + 25 x 2003 (2025 )

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 modelling of Schneeferner (below Zugspitze)

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Modelling of the disappearance of Schneeferner

Weber, Mayer & Hagg (2007) Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Summary and conclusions:

• Water yield from glacierized mountain regions is high in hot and dry years, thus maintaining rather high minimal flows, however, this compensating effect will be lost when the glaciers are gone

• Glacierized basins are a source region for floods especially during periods of strong mass loss and in combination with heavy rainfall up to high elevations

• Streamflow forecasts of rivers originating in glacier areas should also consider the „hydrological“ state of glaciers: storage capacity of firn areas vs. fast drainage of bare ice areas

www.glaciology.de www.glaziologie.de

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Thank you for your attention ….. Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 …and a special „thank you“ to my colleague Markus Weber

Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Foto: Wilfried Haeberli August 2003

Flaz

Inn

Samedan Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007 Töss, Schweiz, ohne Gletscher, 28. August 2003 Commission for Glaciology, Bavarian Academy of Sciences, Munich 2007