Interactive effects of vegetation and sediment properties on erosion of salt marshes in the Northern Adriatic Sea

Lo, Veronica; Bouma, Tjeerd J.; Belzen, Jim van; Colen, C. Van; Airoldi, Laura

doi:10.1016/j.marenvres.2017.09.006

Cited by 53 publications

(60 citation statements)

References 47 publications

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“…While the direct role of vegetation under design conditions is limited, it does play an important indirect role in the medium to long term via bio-geomorphological interactions. Vegetation affects geomorphology via wave attenuation under moderate conditions (M€ oller et al, 2014), subsequent sediment trapping (Mudd et al, 2010), and stabilization of the salt marsh platform with its root systems (Francalanci et al, 2013;Lo et al, 2017).…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Assessing safety of nature-based flood defenses: Dealing with extremes and uncertainties

Vuik

Vuren

Borsje

et al. 2018

Coastal Engineering

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Vegetated foreshores adjacent to engineered structures (so-called hybrid flood defenses), are considered to have high potential in reducing flood risk, even in the face of sea level rise and increasing storminess. However, foreshores such as salt marshes and mangrove forests are generally characterized by relatively strong temporal and spatial variations in geometry and vegetation characteristics (e.g., stem height and density), which causes uncertainties with regards to their protective value under extreme storm conditions. Currently, no method is available to assess the failure probability of a hybrid flood defense, taking into account the aforementioned uncertainties. This paper presents a method to determine the failure probability of a hybrid flood defense, integrating models and stochastic parameters that describe dike failure and wave propagation over a vegetated foreshore. Two dike failure mechanisms are considered: failure due to (i) wave overtopping and (ii) wave impact on revetments. Results show that vegetated foreshores cause a reduction in failure probability for both mechanisms. This effect is more pronounced for wave impact on revetments than for wave overtopping, since revetment failure occurs at relatively low water levels. The relevance of different uncertainties depends on the protection level and associated dike height and strength. For relatively low dikes (i.e., low protection levels), vegetation remains stable in design conditions, and plays an important role in reducing wave loads. In case of higher protection levels, hence for more robust dikes, vegetation is less important than foreshore geometry, because of expected stem breakage of the vegetation under these more extreme conditions. The integrated analysis of uncertainties in hydraulic loads, dike geometry and foreshore characteristics in this paper enables the comparison between nature-based flood defenses and traditionally engineered solutions, and allows coastal engineers to design hybrid flood defenses worldwide.

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Section: Discussion Of Resultsmentioning

confidence: 99%

Assessing safety of nature-based flood defenses: Dealing with extremes and uncertainties

Vuik

Vuren

Borsje

et al. 2018

Coastal Engineering

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“…( a ) Diagram of the hydraulic wave flume and sensors. The wave flume is a further elaboration of the wave mesocosms used by La Nafie et al () and the wave tanks used by Wang et al () and (Lo et al ), and ( b ) diagram of the top view of the wave flume. The total length of the flume is 3.5 m, 0.6 m wide, and 0.8 m high.…”

Section: Methodsmentioning

confidence: 99%

Role of eelgrass on bed‐load transport and sediment resuspension under oscillatory flow

Marin‐Diaz

Bouma

Infantes

2019

Limnology & Oceanography

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Coastal vegetation is widely attributed to stabilize sediment. While most studies focused on how canopy causes flow reduction and thereby affects sediment dynamics, the role of roots and rhizomes on stabilizing the surface sediment has been less well studied. This study aims to quantify interactions between above‐ and belowground biomass of eelgrass (i.e., living Zostera marina plants and mimics) with surface sediment erosion (i.e., bed load and suspended load), under different hydrodynamic forcing that was created using a wave flume. Belowground biomass played an important role preventing bed‐load erosion, by roughly halving the amount of sediment transported after being exposed to maximal orbital velocities of 27 cm s−1, with and without canopy. Surprisingly, for suspended sediment transport, we found opposite effects. In the presence of eelgrass, the critical erosion threshold started at lower velocities than on bare sediment, including sand and mud treatments. Moreover, in muddy systems, such resuspension reduced the light level below the minimum requirement of Z. marina. This surprising result for sediment resuspension was ascribed to a too small eelgrass patch for reducing waves but rather showing enhanced turbulence and scouring at meadow edges. Overall, we conclude that the conservation of the existent eelgrass meadows with developed roots and rhizomes is important for the sediment stabilization and the meadow scale should be taken into account to decrease sediment resuspension.

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“…Once established, however, perennials are expected to be less vulnerable than annuals. Surmountable sedimentation, erosion and sediment dynamics are species specific but also life stage specific and depend on temporal and spatial manifestations of sediment dynamics Cao et al 2018;Langlois et al 2003;Lo et al 2017).…”

Section: Sedimentation Reduced Establishmentmentioning

confidence: 99%

Multiple Environmental Variables Affect Germination and Mortality of an Annual Salt Marsh Pioneer: Salicornia procumbens

Regteren

Meesters

Baptist

et al. 2020

Estuaries and Coasts

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Salt marshes, providing numerous ecosystem services, are degrading worldwide. To effectively aid conservation and restoration efforts, increased knowledge on marsh expansion processes and the initial establishment of pioneer vegetation is essential. In this study, we disentangle environmental drivers that affect the lifecycle of the annual pioneer Salicornia procumbens at the salt marsh edge. We studied the effect of various environmental variables on the start of germination, germination success and mortality before seed-set in a field experiment in the Dutch Wadden Sea at Westhoek. Our results indicate that temperature and sedimentation inhibited the initiation of germination. Once germination occurred, higher precipitation rates increased germination success. In contrast, sedimentation rates above 0.5 mm day −1 halved germination success through burial of freshly sprouted seedlings. Unexpectedly, natural germination was low, indicating that seed availability may have been limited, despite a seed source nearby. Frequent inundation, extended periods without inundation (through desiccation of the soil) and a highly dynamic bed level increased mortality before seed-set. Consequently, bed-level dynamics (erosion, sedimentation and bed-level variation) impact seed production dually (decrease germination and increase mortality) and thus potentially reproduction success. A high seed reproduction is crucial for annuals, such as S. procumbens, to re-establish the following year. Next to advancing our general knowledge of natural salt marsh expansion, results in this study can also be used to assess the potential of a given site for salt marsh stimulation or restoration. Seed availability and local bedlevel dynamics are key in the successful establishment of a salt marsh pioneer: Salicornia procumbens.

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Interactive effects of vegetation and sediment properties on erosion of salt marshes in the Northern Adriatic Sea

Cited by 53 publications

References 47 publications

Assessing safety of nature-based flood defenses: Dealing with extremes and uncertainties

Assessing safety of nature-based flood defenses: Dealing with extremes and uncertainties

Role of eelgrass on bed‐load transport and sediment resuspension under oscillatory flow

Multiple Environmental Variables Affect Germination and Mortality of an Annual Salt Marsh Pioneer: Salicornia procumbens

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