Transcript storm surges. - hvonstorch.de

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
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?
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, 1953
German Bight and Hamburg 1962
Baltic Sea – Germany and Denmark, 1872
Storm Nargis, 2008
Bhola, 1970
Bangladesh cyclone, 1991
Katrina, 2005
Spatial distribution of storm surge risks according to Munich Re
Scientific Issues
a) 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 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.)
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 accepted
3% of all waves –
2 l/(m∙s)
–
0,1-1,0 l/(m∙s) –
Lower Saxony (Germany)
Schleswig-Holstein (Germany)
The Netherlands
Coastal Defense:
acceptable wave overtopping
Niemeyer & Kaiser 2008, NLWKN
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)
Erik Pasche, TU HH
Cascading flood compartments
Example Hamburg
Erik Pasche, TU HH
Cascading flood compartments
Example Hamburg
Erik Pasche, TU HH
Cascading flood compartments
Example Hamburg
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
[m]
Albrecht et al., 2010
Increase of sea level in
the German Bight
Case of German Bight
Temporal
development of intraseasonal 99%ile of
high tide levels AFTER
subtraction of annual
mean high tide
and mean annual high
tide
in Cuxhaven
(Germany)
until 2005.
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
shallow water
equation of vertically
averaged movement
1
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
Black curve: observed values
Blue curve: Aberdeen nudged (ABE)
• Linear long-term
trends are closer to the
observed trends
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)
Only the effect of anthropogenic
climate change (A2, B2)
- No effect of water works.
Scenarios
2030, 2085
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 transdisciplinary attention.
Hans von Storch
[email protected]