BOKU-Met Herbert Formayer
Impact of Climate Change on Lake Neusiedl and potential adaptation strategies
Herbert Formayer Institute of Meteorology University of Natural Resources and Applied Life Sciences, Vienna
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert FormayerBases on the results of the research project financed by the “Landesregierung Burgenland” „Auswirkungen einer Klimaänderung auf den Wasserhaushalt des Neusiedler Sees“
O. Univ. Prof. Dr. Helga KROMP-KOLB A.o. Prof. Dipl.Ing. Dr. Josef EITZINGER Dipl. Ing. Gerhard KUBU Mag. Dr. Herbert FORMAYER Mag. Dr. Patrick HAAS Dipl. Ing. Thomas GERERSDORFER Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Outline
¾Motivation
¾Methods
¾Results
¾Adaptation strategies
¾Some Conclusions
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Motivation
¾Lake Neusiedl is a shallow “Steppensee” which means, that he has no natural outflow.
¾Observed low lake levels showed first negative effects on tourism (especially sailing) in 2003.
¾ Drying out of lake Neusiedl has been observed several times in the past (last time in 1860s).
¾Tourism at Lake Neusiedl and surrounding is an important regional economic factor.
¾This region is an important European bird breeding region. Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Motivation Observed lake level fluctuations
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Hydrology
Lake Catchment: 1.120 km²
Lake Area: ~ 315 km²
From this ~ 175 km² Reed
and 140 km² free water:
Lake depth: < 2m
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Hydrology Water balance Inflow: Precipitation on the Lake 78 % River discharge (manly the river Wulka) 20 % Ground water inflow 2 %
Losses: Evaporation 90 % Channel (flood protection) 10 %
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Hydrology
Lake evaporation: Dalton approach with reed correction
W = × Ws O − eTevfE ))(()(
Ew = Evaporation es = saturation water vapour at water temperature e = water vapour in air f(v) = wind function (linear for lake Neusiedl)
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Hydrology Lake temperature: Richter approach
Observed andTatsächliche simulated und simulierte water Wassertemperatur temperature in 2003 2003
35
30
25
20
15 Messdaten 10 n. Richter v3 5
Temperatur [°C] Temperatur 0
-5
-10
-15
Dez Dez Jän Mär Mär Apr Mai Jun Jul Aug Sep Okt Nov Dez Jän Jahr 2003
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Hydrology Skills of the lake level model
Annual maximumJährliche and minimum Höchst- und Lake Tiefstwasserstände levels observed and modelled
116,00
115,80
115,60 Jahresmax 115,40 Jahresmax ber 115,20 Jahresmin 115,00 Jahresmin ber Pegel [m ü.A.] Pegel 114,80
114,60
114,40 2000 1995 1985 1990 1975 1980 1970 1965 Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Climate Observed climate
AnomalienTemperature des Jahresmitteltemperatur anomaly at the[°C] für lake die RegionNeusiedl Neusiedlersee area
2.5
2
1.5
1
0.5
0
-0.51775 1785 1795 1805 1815 1825 1835 1845 1855 1865 1875 1885 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995
Temperaturanomalie [°C] -1
-1.5 Filter Temperaturanomalie -2 Adaptation to Climatic Change in the European Alps Datasource: ZAMG -2.5 Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Climate Observed climate
Precipitation anomaly in the Lake Neusiedl region
40
30
20
10
0 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 -10
-20 Precipitation anomaly [%]
-30
Filter (20y) -40 Anomaly
-50 Datasource ZAMG
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Climate Scenario preparation: ¾Based on ECHAM4 IS92a GHG only for 2000 - 2049. ¾Statistical downscaling for temperature with analogue technique using relative topography 850-700 hPa as predictor field on daily base. ¾Calibrating a weather generator (Lars Wgen) for periods 1961-1990 and 1991-2004 to Station Neusiedl. ¾Run the weather generator for the periods 2010-2030 and 2030-2049 using only the temperature changes. ¾Relative humidity is estimated from the Temperature diurnal range. ¾Wind speed is set to observed monthly means.
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Climate Climate change signal:
Jahresgang der Temperaturänderung in Neusiedl am See bezogen auf die Observed and scenarioKlimanormalperiode for Temperature 1961-1990 change in the lake Neusiedl region compared to 1961-1990 4.0 Jahresmittel: 3.5 91-04 91-04: 0.7 10-30 10-30: 1.9 3.0 30-50 30-50: 2.5
2.5
2.0
1.5
1.0
Temperaturänderung [°C] Temperaturänderung 0.5
0.0 JFMAMJJASOND -0.5 Monat Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Method - Climate
Model set up: ¾With the average climate of the periods 1961-1990, 1991-2004 and the temperature change for 2010-2030 and 2030-2049 the weather generator was run for 500 years. ¾ For the scenario periods the weather generator was rerun with modified precipitation from – 20 % to + 20 % in 5 % steps ¾The Lake model was driven by the several 500 year weather data on daily base.
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Results
Increase of Lake Neusiedl evaporation compared Anstieg der jährlichen Verdunstung des Neusiedlersees gegenüber der to 1961-1990Klimanormalperiode due to 1961-1990 temperature in Prozent increase.
25 23.3
20 18.3
15
9.6 10 Änderung [%]
5
0 1991-2004 2010-2030 2030-2050 Periode Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Results
Modellierte relative Häufigkeit von Seespiegelunterschreitungen Modelled frequency distribution of lake levels beyond am Neusiedlersee für das derzeitige Klima und a given thresholdTemperaturszenarien. (no precipitation change). 100 1961-1990 90 1991-2004 80 2010-2030 70 2030-2050
60
50
40
30 Relative Häufigkeit [%] 20
10
0
.2 15.4 15.3 115.5 1 1 115.2 115.1 115.0 114.9 114.8 114.7 114.6 114.5 114.4 114.3 114 Seespiegelhöhe [m ü.A.)
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Results
ÄnderungReturn derperiods Jährlichkeit for fürlake eine levels Seespiegelunterschreitung beyond 115.2 mvon for115.2 different (m ü.A.) in Abhängigkeitperiods and von precipitation der Niederschlagsentwicklung changes.
100
90 2030-2050 80 2010-2030 70 1991-2004
60 1961-1990 50 31.3 40 Jährlichkeit 30 20 12.2 10 5.7 1961-1990 0 1991-2004 3.4 2010-2030 -20 -10 -5 0 2030-2050 Periode +5 +10 +20 Niederschlagsängerung [%]
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Results
Return periods for different lake levels for the different
periods and precipitationJährlichkeit von Pegelunterschreitungen as in 1991-2004.
1000
500 500
250 250 167 167 125 100 83 83 83 71 50 36 31 31 25 23 25 19 17 16 Jährlichkeit. 12 13 10 10 9 7 Szenario 61-90 5 5 6 Szenario 91-04 4 3 Szenario 2020 2 3 3 2 Szenario 2040 2 2 1 1 1 1 1 1 115,60 115,40 115,20 115,00 114,80 114,60 114,40 114,20 114,00 Pegelstand {m ü.A.] Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Adaptation strategies
Only possibility to stabilize the lake level is to bring in water - Two options are discussed:
¾Water from the ground water table (Uferfiltrat) of the Danube. ¾Water from the river Raab from the Hungarian side.
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Adaptation strategies
Problem is the large amount of water – to rise the lake level 1 mm ~ 300.000 m³ water are needed.
To bring the water from the Danube to lake Neusiedl it has to be bumped an altitude of more than 30 m – Very energy intensive.
When the water is needed most, the river Raab also has very low discharge.
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Adaptation strategies
Additional problems:
The mixing of the salty lake water with the Danube water may cause a clearing of the water, leading to massive growth of water plants.
Large additional water inflow may decrease the salinity and accelerate the growth of reed.
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer Some Conclusions
¾Lake Neusiedl is very sensitive to climate change. ¾A warming of 2.5 K leads to an evaporation increase of more than 20 %. ¾To compensate the evaporation losses an precipitation increase of + 20 % is needed, which is not very likely looking on state of the art regional scenarios. ¾Critical lake levels for tourism as 150.0 m will change there return period from some 250 years in the past to less then 10 years within the next decades. ¾Adaptation seems to be possible but may be expensive and include some possible negative biological reactions in the lake.
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006 BOKU-Met Herbert Formayer
Thank you for your attention!
Adaptation to Climatic Change in the European Alps Wengen 2006 Workshop 04 – 06 October 2006