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Are there changes in the frequency-magnitude relationship of floods?

Are there changes in the frequency-magnitude relationship of floods?. Christian Dobler Institute of Geography, University of Innsbruck. www.alpinesicherheit.com. Are there changes in the frequency-magnitude relationship of floods? Christian Dobler. Overview.

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Are there changes in the frequency-magnitude relationship of floods?

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  1. Are there changes in the frequency-magnitude relationship of floods? Christian Dobler Institute of Geography, University of Innsbruck www.alpinesicherheit.com Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  2. Overview • Frequency and Magnitude relationship of floods • Natural disasters in Tyrol/Vorarlberg in recent past Avalanches 1999 Floods 1999, 2002, 2005 • Current research project Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  3. Frequency – Magnitude Relationship of floods probability of occurence probability c discharge [m³/s] a b Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  4. Avalanches 1999 – Galtür/Ischgl • meteorological data - Snow high 210 cm- 10-day fresh snow 247 cm -> highest values measured so far • 38 dead persons, € 5.27 mill. damages • Return period: above 150 years www.bmlv.gv.at Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  5. Floods 2005 • meteorological data - highest precipitation values within 24 hours - e.g. Bizau: 194mm (maximum so far 156mm) • discharge - return period above 5000 years in Paznaun Valley - in Innsbruck maximum value since 1870 • Damages in Tyrol/Vorarlberg € 442.2 million www.alpinesicherheit.com Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  6. Floods 1999, 2002, 2005(Bregenzer Ache) three floods with return period of 100 years within 7 years probability therefore 1 : 29500 Highest floods in the years 1951 - 2005 Hydrographischer Dienst Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  7. Conclusion increasing number of extreme events within few years Answers – not yet? First effects of climate change? • Observed increase in precipitation intensity • Increase in westerly weather patterns during winter Within the natural variability? Not transferable to the Alps Sturm et al. 2001,IPCC 2007, Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  8. Impacts of climate change on floods KLIWA 2006 Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  9. Impacts of climate change on floods probability of occurence probability c discharge [m³/s] a b Current Protective measures Adaptation! KLIWA 2006 Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  10. Impacts of climate change on floods Hydrographischer Dienst Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  11. Risk Management Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  12. Research Project Impacts of climate change on the frequency and magnitude of floods Difficulties: • high demand on temporal and spatial resolution of data • Complex topography Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  13. Methodology Climate Models Present Climate: large-scale atm. data Future Scenario: large-scale atm. data Weather Generator Expanded Downscaling (EDS) Present Climate: local meteor. data Future Scenario: local meteor. data Hydrological Model Present Climate: discharge Future Scenario: discharge Statistical Analysis Present Climate: statistics Future Scenario: statistics Changes in hazard potential? Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  14. Global climate models AOGCMs atmosphere-ocean general circulation models -> direct use restricted to large spatial scales Downscaling: - dynamical downscaling - statistical downscaling Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  15. Regional Climate Modelse.g. REMO Comparison REMO Control Run – Observation (1981 – 2000) TEMPERATURE Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  16. Regional Climate Modelse.g. REMO -> not directly applicable for hydrological modelling Comparison REMO Control Run – Observation (1981 – 2000) PRECIPITATION Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  17. Statistical downscaling Statistical relationship between the large-scale AOGCMs output („predictor“) and the local scale target variable („predictand“) Assumptions: • larger-scale variables are more reliably simulated • relationships remain valid in a changed climate Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  18. www.nebelspalter.ch Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

  19. Thank you for your attention! Are there changes in the frequency-magnitude relationship of floods? Christian Dobler

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