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| Titel |
Evaluating future flooding risks by using a probabilistic approach to
include wave height distributions in sea level variations |
| VerfasserIn |
Ulpu Leijala, Jan-Victor Björkqvist, Kimmo K. Kahma, Milla M. Johansson, Hilkka Pellikka, Jani Särkkä |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128650
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| Publikation (Nr.) |
 EGU/EGU2016-8656.pdf |
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| Zusammenfassung |
| Assessing sea flood risks has an essential role in future coastal planning as climate change
drives forward the global sea level rise. Safe planning of land utilization and building in
coastal areas requires capability to estimate sea level behaviour all the way to 100–200 years
ahead. The coastal effect of the sea level is always affected also by the wave conditions,
which may vary greatly depending on location. An archipelago acts as an efficient shield
against the largest waves penetrating to the shoreline. However, part of the energy of the
waves passes through the archipelago and coastal wave height conditions, depending for
example on the shape of the shoreline and topography of the seabed, must be evaluated close
to the shore separately.
The probability of high sea level and wind generated high waves occurring
simultaneously is lower than the probability of one of the components occurring alone.
Summing the maximum sea level and maximum wave height components together can thus
lead to an overestimation of the joint effect. For this reason a method based on probability
distributions is reasonable and preferable. In this study, a method of combining sea
level and wave height distributions using a location specific probability approach
is introduced. First estimates of the joint effect of high sea level and high waves
at several locations at the archipelago area on the southern coast of Finland are
presented.
Constructing sea level scenarios including the effect of wind waves until the end of the
century demands knowledge of both sea level and wave height variability in the past,
and global mean sea level predictions for the future. In our study, an estimate of
short-term sea level variability is based on 30 years (1982–2011) of hourly data
from the Helsinki tide gauge located on the coast of the Gulf of Finland. Future
predictions for the long-term mean sea level changes at Helsinki are based on scenarios
taking into account the global mean sea level rise, local land uplift, and changes in
the Baltic Sea water balance. Wave statistics in turn are based on individual wave
buoy measurements conducted at several sites on the coast off Helsinki during
2012–2014.
The method developed in this study is a new tool for evaluating extreme sea level events
including the effect of high sea level jointly with high wave height. The method
can be applied to any coastal areas where sufficient sea level and wave data are
available. The probabilistic approach used here gives a possibility to evaluate the risk
levels of different infrastructures on the coast for the present and for the future. |
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