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Storm surges: Phenomena, modelling and scenarios

19-24 August, 2012 Mini-symposium "Mechanics of natural disasters" at the 23rd International Congress of Theoretical and Applied Mechanics, Beijing. Storm surges: Phenomena, modelling and scenarios. Hans von Storch Institute of Coastal Research Helmholtz-Zentrum Geesthacht Germany.

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Storm surges: Phenomena, modelling and scenarios

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  1. 19-24 August, 2012 Mini-symposium "Mechanics of natural disasters" at the 23rd International Congress of Theoretical and Applied Mechanics, Beijing Storm surges: Phenomena, modelling and scenarios Hans von Storch Institute ofCoastal Research Helmholtz-Zentrum Geesthacht Germany

  2. Hans von Storch Director of Institute for Coastal Research, Helmholtz Zentrum Geesthacht (HZG), near Hamburg, Professor at the Meteorological Institute of Hamburg University Works also with social and cultural scientists. Who is this?

  3. Overview • Storm surges – global phenomenon, with regional manifestation. • Physics of storm surges: The kid in the bathtub • The case of the German Bight • Modelling storm surges • Examples for attribution of causes for changing storm surge risk

  4. Overview • Storm surges – global phenomenon, with regional manifestation. • Physics of storm surges: The kid in the bathtub • The case of the German Bight • Modelling storm surges • Examples for attribution of causes for changing storm surge risk

  5. Midlatitudestorms The Netherlandsand UK, 1953 German Bightand Hamburg 1962 Baltic Sea – Germany andDenmark, 1872

  6. Storm Nargis, 2008Bhola, 1970Bangladesh cyclone, 1991Katrina, 2005

  7. Spatial distribution of storm surge risks according to Munich Re

  8. Scientific Issues • Physicsofstormsurges • Predictionofstormsurges • Coastaldefense – newoptions • Disastermanagement – newoptions • Changingrisks – Climatechangeandotherfactors

  9. Overview • Storm surges – global phenomenon, with regional manifestation. • Physics of storm surges: The kid in the bathtub • The case of the German Bight • Modelling storm surges • Examples for attribution of causes for changing storm surge risk

  10. Meteorological component of anomalous sea level (Storm, waves, seiches) Regional sea level Ocean currents, filling of marginal seas (Baltic Sea), Regional affects of changing mass distributions Global sea level Volume of the ocean (thermal expansion, melting of ice sheets, glaciers etc.)

  11. Graphics: Michael Schrenk

  12. Graphics: Michael Schrenk

  13. Graphics: Michael Schrenk

  14. Graphics: Michael Schrenk

  15. Graphics: Michael Schrenk

  16. Coastal Defense: acceptable wave overtopping Niemeyer & Kaiser 2008, NLWKN presently accepted 3% of all waves – Lower Saxony (Germany) 2 l/(m∙s) – Schleswig-Holstein (Germany) 0,1-1,0 l/(m∙s) – The Netherlands

  17. Coastal Defense: acceptable wave overtopping Niemeyer & Kaiser 2008, NLWKN Tests with elevated wave overtopping in Delfzijl (The Netherlands) • No damages at the grass surfacewith overtopping of up zo 50 l/(m∙s) • Functionality maintained even in case of pre-set surface damages up to 50 l(m∙s)

  18. Cascading flood compartmentsExample Hamburg Erik Pasche, TU HH

  19. Cascading flood compartmentsExample Hamburg Erik Pasche, TU HH

  20. Cascading flood compartmentsExample Hamburg Erik Pasche, TU HH

  21. Overview • Storm surges – global phenomenon, with regional manifestation. • Physics of storm surges: The kid in the bathtub • The case of the German Bight • Modelling storm surges • Examples for attribution of causes for changing storm surge risk

  22. [m] Increaseofsealevelin the German Bight Albrecht et al., 2010

  23. Case of German Bight Temporal development of intra-seasonal 99%ile of high tide levels AFTER subtraction of annual mean high tide and mean annual high tide in Cuxhaven (Germany) until 2005.

  24. Overview • Storm surges – global phenomenon, with regional manifestation. • Physics of storm surges: The kid in the bathtub • The case of the German Bight • Modelling storm surges • The case of Hamburg – assessment and options

  25. Tidal modelling: hydraulic vs. numerical

  26. shallow water equation of vertically averaged movement 1

  27. von Storch, H., 2001: Models. In: H. von Storch and G. Flöser (Eds): Models in Environmental Research. Springer Verlag, 17-33

  28. Aspelien, T., 2006: The use of long-term observations in combination with modelling and their effect on the estimation of the North Sea storm surge climate. PhD thesis, Hamburg, 106pp Operational modelling by assimilation of „upstream“ data Trygve Aspelien, pers. comm

  29. Trygve Aspelien, pers. comm

  30. Trygve Aspelien, pers. comm

  31. Inter-annual variability (1958-2001) Cuxhaven • After nudging: • Better reproduced inter-annual variability Black curve: observed values Blue curve: Aberdeen nudged (ABE) Red curve: Control experiment (CTL) • Linear long-term trends are closer to the observed trends • Improvement from CTL in the percentiles (1,5,10,90,95,99) of surge when Aberdeen is nudged (Brier skill score): • Cuxhaven: 58-80% • Borkum: 10-76% Trygve Aspelien, pers. comm

  32. Overview • Storm surges – global phenomenon, with regional manifestation. • Physics of storm surges: The kid in the bathtub • The case of the German Bight • Modelling storm surges • Examples for attribution of causes for changing storm surge risk

  33. http://www.loicz.org/imperia/md/content/loicz/stormsurges/15_syvitski.pdfhttp://www.loicz.org/imperia/md/content/loicz/stormsurges/15_syvitski.pdf

  34. Hamburg – storm surges

  35. Difference of water level maxima at the mouth of the estuary (Cuxhaven) and in Hamburg (St. Pauli)

  36. Only the effect of anthropogenic climate change (A2, B2) - No effect of water works. Scenarios 2030, 2085

  37. Conclusions • Storm surges are a serious issue • Storm surges are an interesting issue. • Storm surges is a global phenomenon but usually considered on a regional or even local scale. • Issues relate to the phenomenon, prediction, risk management, disaster management and dealing with changing conditions • The phenomenon allows for efficient description (risk statistics, forecast) by numerical modeling • Risks are changing due to geophysical conditions (sea level, wind statistics), delta sinking (resource extraction) and water works (dredging shipping lanes, coastal protection) • Storm surges is a societal issue, which needs transdis-ciplinary attention.

  38. Hans von Storch hvonstorch@web.de

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