Wave dissipation over macro-tidal saltmarshes: Effects of marsh edge typology and vegetation change

Möller, Iris; Spencer, T.

doi:10.2112/1551-5036-36.sp1.506

Cited by 205 publications

(159 citation statements)

References 27 publications

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“…6) is in line with observations made in flume studies (Bouma et al 2005b(Bouma et al , 2010). An earlier field study also reported that the most rapid attenuation of waves occurs over the most seaward 10 m of a salt marsh (Möller and Spencer 2002). The present study clearly showed temporal changes in wave attenuation due to the effect of Fig.…”

Section: Cross-shore and Temporal Changes In Wave Attenuation Rate Insupporting

confidence: 80%

“…(<0.4 m high) in North Norfolk, UK, a decrease in significant wave height was measured at a rate of 0.34%/ m (Möller et al 1999). A comparative wave attenuation rate (0.54%/m) was found across a salt marsh in Essex, UK, formed of similar vegetation species (Möller and Spencer 2002). In the Yangtze Estuary, a significant wave height attenuation rate of 0.95%/m was measured across a marsh formed of taller (0.5 m) native S. mariqueter vegetation (Yang et al 2008).…”

Section: Locationsmentioning

confidence: 89%

“…As suggested in Table 1, the wave attenuation rate over the S. alteniflora marsh at the present study site was 1 to 2 magnitudes higher than that on the adjacent mudflat. Although significant differences in wave attenuation between salt marsh and unvegetated areas have been well addressed (e.g., Möller et al 1996;Yang 1998;Möller and Spencer 2002), little is known about how much of the difference is attributed to the presence of vegetation. Wave attenuation is sensitive to changes in elevation gradient (Kurian and Baba 1987).…”

Section: Causes Of Differences In Wave Attenuation Between Salt Marshmentioning

confidence: 99%

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Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Yang

Shi

Bouma

et al. 2011

Estuaries and Coasts

141

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To quantify wave attenuation by (introduced) Spartina alterniflora vegetation at an exposed macrotidal coast in the Yangtze Estuary, China, wave parameters and water depth were measured during 13 consecutive tides at nine locations ranging from 10 m seaward to 50 m landward of the low marsh edge. During this period, the incident wave height ranged from <0.1 to 1.5 m, the maximum of which is much higher than observed in other marsh areas around the world. Our measurements and calculations showed that the wave attenuation rate per unit distance was 1 to 2 magnitudes higher over the marsh than over an adjacent mudflat. Although the elevation gradient of the marsh margin was significantly higher than that of the adjacent mudflat, more than 80% of wave attenuation was ascribed to the presence of vegetation, suggesting that shoaling effects were of minor importance. On average, waves reaching the marsh were eliminated over a distance of ∼80 m, although a marsh distance of ≥100 m was needed before the maximum height waves were fully attenuated during high tides. These attenuation distances were longer than those previously found in American salt marshes, mainly due to the macrotidal and exposed conditions at the present site. The ratio of water depth to plant height showed an inverse correlation with wave attenuation rate, indicating that plant height is a crucial factor determining the efficiency of wave attenuation. Consequently, the tall shoots of the introduced S. alterniflora makes this species much more efficient at attenuating waves than the shorter, native pioneer species in the Yangtze Estuary, and should therefore be considered as a factor in coastal management during the present era of sea-level rise and global change. We also found that wave attenuation across the salt marsh can be predicted using published models when a suitable coefficient is incorporated to account for drag, which varies in place and time due to differences in plant characteristics and abiotic conditions (i.e., bed gradient, initial water depth, and wave action).

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Section: Cross-shore and Temporal Changes In Wave Attenuation Rate Insupporting

confidence: 80%

Section: Locationsmentioning

confidence: 89%

Section: Causes Of Differences In Wave Attenuation Between Salt Marshmentioning

confidence: 99%

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Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Yang

Shi

Bouma

et al. 2011

Estuaries and Coasts

141

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“…Existing evidence for the medial erosion process suggests that above-ground portions of a plant attenuate orbital wave currents within relatively dense vegetated salt marshes, but it has also been shown in steady-flow conditions that these aboveground portions can result in surface scouring in adjacent locations that are less dense (29,30). Moreover, it has been hypothesized that these above-ground portions can actually trigger the formation of the vertical cliff-like edge at the land-water interface (31,32), as a result of relative differences in landward versus seaward flow velocities and wave stresses on either side of the edge (33). Waves can also typically force large block detachment, yet it is currently unknown whether such mass wasting events are likely to be mediated by plant roots.…”

Section: Discussionmentioning

confidence: 99%

Does vegetation prevent wave erosion of salt marsh edges?

Feagin

Lozada-Bernard

Ravens

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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248

154

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This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is bestsuited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.coast ͉ hurricane ͉ wave attenuation ͉ wetland

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“…Habitat loss has been particularly severe and prominent in the coastal zone through land reclamation, development, overfishing and pollution, with European losses being estimated at exceeding 50% of the original area (Airoldi and Beck, 2007). Estuarine habitats, including saltmarshes, mudflats and seagrass beds are important habitats, both as protected areas for wildfowl and fisheries stocks as well as providing an important component of coastal protection via wave dissipation, (Moller and Spencer, 2002). As an acknowledgement of the ecological functions estuaries perform, large areas have been designated under the EC Habitats and Species Directive including; saltmarshes and mudflats.…”

Section: Introductionmentioning

confidence: 99%

Management Implications of Flood/Ebb tidal dominance: its influence on saltmarsh and intertidal habitat stability in Poole Harbour

Gardiner

Nicholls

Tanton

2011

Littoral 2010 – Adapting to Global Change at the Coast: Leadership, Innovation, and Investment

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Saltmarshes are important habitats and have historically declined in the south of the UK and as sea-level rise is predicted to accelerate these losses are expected to increase. In order to explore estuary morphodynamics with relation to accretional and erosional trends at an estuary and sub-estuary scale, historic aerial photography were analysed with saltmarsh changes from 1947 and 2005 quantified. Using the Telemac model developed by HR Wallingford, tidal asymmetry of peak tides and slack duration was mapped and correlations between tidal asymmetry and saltmarsh change examined. Results indicate that there is a significant relationship between areas of flood dominance and the historic accretion of saltmarsh. However, there is no statistical correlation between areas that had experienced erosion and ebb dominance, indicating other dominant drivers of erosion processes. Results using hypsometric calculations suggest that the whole harbour behaves as an ebb dominant system and therefore tends towards erosion. However, when split into a sub-estuary scale, different creek systems show varying morphology and the hypsometry changes. This may have serious management implications where estuaries are manipulated through dredging and development, leading to significant effects on the surrounding intertidal habitats. However, managed realignment planning could also exploit the potential for enhancing flood dominance and hence accretion wherever possible.

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Wave dissipation over macro-tidal saltmarshes: Effects of marsh edge typology and vegetation change

Cited by 205 publications

References 27 publications

Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Does vegetation prevent wave erosion of salt marsh edges?

Management Implications of Flood/Ebb tidal dominance: its influence on saltmarsh and intertidal habitat stability in Poole Harbour

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