storm surges: phenomena, modelling and scenarios hans von storch institute of coastal research...
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Storm surges: Phenomena,
modelling and scenariosHans von Storch
Institute of Coastal ResearchHelmholtz-Zentrum Geesthacht
Germany
19-24 August, 2012 Mini-symposium "Mechanics of natural disasters" at the 23rd International Congress of Theoretical and Applied Mechanics, Beijing
Who is this?
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.
Overview
1. Storm surges – global phenomenon, with regional manifestation.
2. Physics of storm surges: The kid in the bathtub
3. The case of the German Bight
4. Modelling storm surges
5. Examples for attribution of causes for changing storm surge risk
Overview
1. Storm surges – global phenomenon, with regional manifestation.
2. Physics of storm surges: The kid in the bathtub
3. The case of the German Bight
4. Modelling storm surges
5. Examples for attribution of causes for changing storm surge risk
Midlatitude storms
The Netherlands and UK, 1953German Bight and Hamburg 1962Baltic Sea – Germany and Denmark, 1872
Storm Nargis, 2008Bhola, 1970
Bangladesh cyclone, 1991Katrina, 2005
Spatial distribution of storm surge risks according to Munich Re
Scientific Issuesa)Physics of storm surges
b)Prediction of storm surges
c)Coastal defense – new options
d)Disaster management – new options
e)Changing risks – Climate change and other factors
Overview
1. Storm surges – global phenomenon, with regional manifestation.
2. Physics of storm surges: The kid in the bathtub
3. The case of the German Bight
4. Modelling storm surges
5. Examples for attribution of causes for changing storm surge risk
Meteorological component of anomalous sea level(Storm, waves, seiches)
Regional sea levelOcean currents, filling of marginal seas (Baltic Sea),Regional affects of changing mass distributions
Global sea levelVolume of the ocean (thermal expansion, melting of ice sheets, glaciers etc.)
Graphics: Michael Schrenk
Graphics: Michael Schrenk
Graphics: Michael Schrenk
Graphics: Michael Schrenk
Graphics: Michael Schrenk
Coastal Defense: acceptable wave overtopping
Niemeyer & Kaiser 2008, NLWKN
presently accepted3% of all waves – Lower Saxony (Germany)2 l/(m∙s) – Schleswig-Holstein (Germany)0,1-1,0 l/(m∙s) – The Netherlands
Niemeyer & Kaiser 2008, NLWKN
Coastal Defense: acceptable wave overtopping
Tests with elevated wave overtopping in Delfzijl (The Netherlands)
• No damages at the grass surface with overtopping of up zo 50 l/(m s)∙
• Functionality maintained even in case of pre-set surface damages up to 50 l(m s)∙
Cascading flood compartmentsExample Hamburg
Erik Pasche, TU HH
Cascading flood compartmentsExample Hamburg
Erik Pasche, TU HH
Cascading flood compartmentsExample Hamburg
Erik Pasche, TU HH
Overview
1. Storm surges – global phenomenon, with regional manifestation.
2. Physics of storm surges: The kid in the bathtub
3. The case of the German Bight
4. Modelling storm surges
5. Examples for attribution of causes for changing storm surge risk
Albrecht et al., 2010
[m]Increase of sea level in the 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.
Case of German Bight
Overview
1. Storm surges – global phenomenon, with regional manifestation.
2. Physics of storm surges: The kid in the bathtub
3. The case of the German Bight
4. Modelling storm surges
5. The case of Hamburg – assessment and options
Tidal modelling: hydraulic vs. numerical
1
shallow water equation of vertically averaged movement
von Storch, H., 2001: Models. In: H. von Storch and G. Flöser (Eds): Models in Environmental Research. Springer Verlag, 17-33
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
Trygve Aspelien, pers. comm
Trygve Aspelien, pers. comm
Inter-annual variability (1958-2001)Cuxhaven
After nudging:
• Better reproduced inter-annual variability
• Linear long-term trends are closer to the observed trends
Black curve: observed values
Blue curve: Aberdeen nudged (ABE)
Red curve: Control experiment (CTL)
• 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
Overview
1. Storm surges – global phenomenon, with regional manifestation.
2. Physics of storm surges: The kid in the bathtub
3. The case of the German Bight
4. Modelling storm surges
5. Examples for attribution of causes for changing storm surge risk
http://www.loicz.org/imperia/md/content/loicz/stormsurges/15_syvitski.pdf
Hamburg – storm surges
Difference of water level maxima at the mouth of the estuary (Cuxhaven) and in Hamburg (St. Pauli)
Scenarios 2030, 2085
Only the effect of anthropogenic climate change (A2, B2)
- No effect of water works.
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.
Hans von [email protected]