Transcript Storm surges – the case of Hamburg, Germany (invited, session #26

Hamburg – storm surges
Hans von Storch
Plausible cause: more or more
violent storms?
Bärring, 2005; blue - Lund; red – Stockholm
Matulla, C.,
W.
Schöner, H.
Alexandersson, H. von
Storch, and X.L.
Wang, 2007: European
Storminess: Late 19th
Century to Present,
accepted for
publication by Climate
Dynamics
Gaussian low-pass filtered (21 yr) curves for annual 99%tiles of daily
geostrophic wind speeds. The heavy curve is made up by Kremsmünster,
Vienna and Prague-Klementinum while the heavy dashed curve by
Kremsmünster, Vienna and Prague-Karlov.
(note that tails are based on less data then the rest)
Where does the enhanced storm
surge levels Hamburg come from?
• Sea level rise – a few centimeters
• Intensification of storm activity 19601995
• What else has happened in the
coastal/estuarine environment?
Difference in storm surge heights – mouth
of Elbe estuary and Hamburg, 1900- 2005
The tidal change is due to coastal protection measures and modifications of the
tributaries, and to the deepening of the shipping channel. These measure also had
an effect on the heights of severe storm surges – estimates are 45 cm caused by
measures of coastal defense and 15 cm by deepening the shipping channel
(Haake, 2004: 27).
Thus, so far, global warming had no
discernible impact on the storm surge
risk in Hamburg.
Will it have an effect?
- yes, but we may be able to do
something about it.
- No effect of water works.
Scenarios
2030, 2085
Grossmann, I., K. Woth and H. von Storch, 2007: Localization of
global climate change: Storm surge scenarios for Hamburg in 2030 and
2085. Die Küste 71, 169-182
Only the effect of anthropogenic
climate change (A2, B2)
Conclusions
• In the past 40 years, storm surge heights in St. Pauli
have been increased by about 60 cm due to coastal
defense and shipping channel deepening measures
• Scenarios indicate an intensification of about 60 cm
for the end of the 21st century due to global warming.
• “Tide-Elbe” Project, prepared by Hamburg Port
Authority, plans for a deceleration of the tidal
dynamics – primarily for slowing down sedimentation –
but also for reducing storm surge risk.
• It may be possible to “pay” for the future risk by
rectifying the effect of past river bed modifications.