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| Titel |
Wave-vegetation interactions within Baltic coastal reed beds |
| VerfasserIn |
Iris Möller, Jasmin Mantilla-Contreras, Tom Spencer, Adrian Hayes |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250057836
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| Zusammenfassung |
| In the context of sea level rise and the possibility of associated increased storminess the role
of low-lying vegetated coastal margins as natural sea defences (as well as important
conservation areas) is becoming increasingly critical to the sustainable management of
coasts. At the same time, the function of such types of coastal environments as providers of a
range of local and global ecosystem services has become more widely recognised. While a
range of previous studies have highlighted the significance of vegetation as a natural wave
energy buffer, few studies have systematically investigated the variation of this function under
varying water depth and wave exposure. This paper presents detailed field measurements of
wave spectra along two Phragmites australis reed beds under conditions of varying water
depths and levels of exposure on the shores of the southern Baltic Sea. Results are discussed
in the context of the meteorological conditions and geomorphological controls affecting the
vegetated zone. Significant wave height attenuation reached a maximum of 2.6 % m-1
and 11.8 % m-1 at the transition from open water into the reed vegetation at the
sheltered and exposed sites respectively. Wave attenuation through the emergent
reed vegetation was significantly lower in greater water depths, suggesting (i) a
reduced influence of bed friction by small shoots/roots and/or (ii) drag reduction due
to flexing of plants when the wave motion is impacting stems at a greater height
above the bed. For a given water depth, wave dissipation increased with increasing
incident wave height, however, suggesting that, despite their ability to flex, reed
stems may be rigid enough to cause increased drag under greater wave forcing. The
higher frequency part of the wave spectrum (> 0.5 Hz) was preferentially reduced at
the reed margin, confirming the theoretical wave frequency dependence of bottom
friction. The results presented have implications for wider-ranging questions about
the possible impact of increased water depths (sea level rise) and increased storm
surge frequency. The possible significance of biogeomorphological thresholds is
discussed and the need for flexible coastal management approaches highlighted. |
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