Vegetation-wave interactions in salt marshes under storm surge conditions
Rupprecht, F; Möller, I.; Paul, M.; Kudella, M.; Spencer, T.; van Wesenbeeck, B.K.; Wolters, G.; Jensen, K.; Bouma, T.J.; Miranda-Lange, M.; Schimmels, S. (2017). Vegetation-wave interactions in salt marshes under storm surge conditions. Ecol. Eng. 100: 301-315. dx.doi.org/10.1016/j.ecoleng.2016.12.030 In: Ecological Engineering. Elsevier: Amsterdam; London; New York; Tokyo. ISSN 0925-8574; e-ISSN 1872-6992, more |  |
| Author keywords | Wave dissipation; Flow reduction; Coastal wetlands; Biophysical plant properties; Plant breakage; Vegetation resilience; Wave flume experiment; Cauchy number |
| Authors | | Top | - Rupprecht, F
- Möller, I.
- Paul, M.
- Kudella, M.
| - Spencer, T.
- van Wesenbeeck, B.K.
- Wolters, G.
- Jensen, K.
| - Bouma, T.J., more
- Miranda-Lange, M.
- Schimmels, S.
|
| Abstract | Vegetation-wave interactions are critical in determining the capacity of coastal salt marshes to reducewave energy (wave dissipation), enhance sedimentation and protect the shoreline from erosion. Whilevegetation-induced wave dissipation is increasingly recognized in low wave energy environments, little isknown about: (i) the effect of vegetation on wave dissipation during storms when wave heights and waterlevels are highest; and (ii) the ability of different plant species to dissipate waves and to maintain theirintegrity under storm surge conditions. Experiments undertaken in one of the world’s largest wave flumesallowed, for the first time, the study of vegetation-wave interactions at near-field scale, under waveheights ranging from 0.1–0.9 m (corresponding to orbital velocities of 2–91 cm s−1) and water depths upto 2 m, in canopies of two typical NW European salt marsh grasses: Puccinellia maritima (Puccinellia) andElymus athericus (Elymus). Results indicate that plant flexibility and height, as well as wave conditionsand water depth, play an important role in determining how salt marsh vegetation interacts with waves.Under medium conditions (orbital velocity 42–63 cm s−1), the effect of Puccinellia and Elymus on waveorbital velocities varied with water depth and wave period. Under high water levels (2 m) and longwave periods (4.1 s), within the flexible, low-growing Puccinellia canopy orbital velocity was reducedby 35% while in the more rigid, tall Elymus canopy deflection and folding of stems occurred and nosignificant effect on orbital velocity was found. Under low water levels (1 m) and short wave periods(2.9 s) by contrast, Elymus reduced near-bed velocity more than Puccinellia. Under high orbital velocities(≥74 cm s−1), flattening of the canopy and an increase of orbital velocity was observed for both Puccinelliaand Elymus. Stem folding and breakage in Elymus at a threshold orbital velocity ≥ 42 cm s−1coincided witha levelling-off in the marsh wave dissipation capacity, while Puccinellia survived even extreme waveforces without physical damage. These findings suggest a species-specific control of wave dissipation bysalt marshes which can potentially inform predictions of the wave dissipation capacity of marshes andtheir resilience to storm surge conditions. |
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