Vegetation interactions with geotechnical properties and erodibility of salt marsh sediments

Evans, Ben; Brooks, Helen; Chirol, Clémentine; Kirkham, Matthew; Möller, Iris; Royse, Katherine; Spencer, Kate L.; Spencer, Tom

doi:10.1016/j.ecss.2021.107713

Cited by 17 publications

(9 citation statements)

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“…In this study, P. australis formed dense, shallow mats of roots which could benefit the sediment stability compared to species that only develop roots in the deeper sediment layers, suggesting that the type of roots and their structure might play an important role in the sediment stability (Feagin et al, 2009;De Battisti et al, 2019). Other studies emphasize the effect of sediment composition, such as the decreasing sediment stability in function of an increasing fraction of organic substances (Gillen et al, 2021) or an increasing fraction of coarser, sandy sediments (Schoutens et al, 2019;Evans et al, 2021). Moreover, climate induced environmental changes might alter the stability of tidal marshes, i.e.…”

Section: Suggestions For Further Researchmentioning

confidence: 56%

“…Firstly, sediment composition is known to be a key determinant for the susceptibility to erosion of sediment surfaces (Lo et al, 2017;De Battisti et al, 2019;Evans et al, 2021). Thus our finding of high sediment bed resistance to vertical erosion is likely to also be determined by case-specific sediment properties.…”

Section: Marsh Sediment Stability Under Short-term High Flow Velocitiesmentioning

confidence: 80%

“…That is, a high fraction of root biomass near the sediment surface (Figure 4) might cause a decrease in bulk density by creating pores and voids between the sediment particles (Brain et al, 2012;Chen et al, 2012;Jafari et al, 2019). Root networks change the sediment characteristics both through the presence of dead and living roots which then function as a structural framework for the sediment aggregates, promote the formation of pores and enhance drainage capacity, hence increasing the erosion resistance of the sediment surface (Gyssels et al, 2005;Grabowski et al, 2011;Evans et al, 2021). Only in the two highest flow conditions (after 10-12 h of cumulative flow exposure), uprooting of fine roots covering the entire sediment surface was observed (Figure 8).…”

Section: Marsh Sediment Stability Under Short-term High Flow Velocitiesmentioning

confidence: 99%

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Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense

et al. 2022

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Nature-based strategies, such as wave attenuation by tidal marshes, are increasingly proposed as a complement to mitigate the risks of failure of engineered flood defense structures such as levees. However, recent analysis of historic coastal storms revealed smaller dike breach dimensions if there were natural, high tidal marshes in front of the dikes. Since tidal marshes naturally only experience weak flow velocities (~0-0.3 ms-1 during normal spring tides), we lack direct observations on the stability of tidal marsh sediments and vegetation under extreme flow velocities (order of several ms-1) as may occur when a dike behind a marsh breaches. As a first approximation, the stability of a tidal marsh sediment bed and winter-state vegetation under high flow velocities were tested in a flume. Marsh monoliths were excavated from Phragmites australis marshes in front of a dike along the Scheldt estuary (Dutch-Belgian border area) and installed in a 10 m long flume test section. Both sediment bed and vegetation responses were quantified over 6 experimental runs under high flow velocities up to 1.75 ms-1 and water depth up to 0.35 m for 2 hours. These tests showed that even after a cumulative 12 hours exposure to high flow velocities, erosion was limited to as little as a few millimeters. Manual removal of the aboveground vegetation did not enhance the erosion either. Present findings may be related to the strongly consolidated, clay- and silt-rich sediment and P. australis root system in this experiment. During the flow exposure, the P. australis stems were strongly bent by the water flow, but the majority of all shoots recovered rapidly when the flow had stopped. Although present results may not be blindly extrapolated to all other marsh types, they do provide a strong first indication that marshes can remain stable under high flow conditions, and confirm the potential of well-developed tidal marshes as a valuable extra natural barrier reducing flood discharges towards the hinterland, following a dike breach. These outcomes promote the consideration to implement tidal marshes as part of the overall flood defense and to rethink dike strengthening in the future.

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Section: Suggestions For Further Researchmentioning

confidence: 56%

Section: Marsh Sediment Stability Under Short-term High Flow Velocitiesmentioning

confidence: 80%

Section: Marsh Sediment Stability Under Short-term High Flow Velocitiesmentioning

confidence: 99%

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Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense

et al. 2022

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“…As in the case of dune systems, salt marshes are considered as typical cases of biogeomorphological systems, especially under tropical climates (Li et al, 2021). In fact, salt marsh reclamation or the removal of vegetation from marshes usually has the same consequence as the effects of strong currents and waves: shoreline erosion and retreat (Brunier et al, 2019;Zhang et al, 2021;Evans et al, 2022).…”

Section: Low Sedimentary Coasts: Barrier Islands Lagoons Salt Marshes...mentioning

confidence: 99%

The complexity of studying coasts: From forms and processes to management

Prieto

2022

CIG

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Coastal environments are characterized by their high dynamism, related to the interaction between marine agents (winds, waves, currents, sea level changes) and continental forms and processes. The present article summarizes the main morphodynamic characteristics of coasts and the resulting environments. Different oscillations of the sea level are considered, depending on their amplitude and frequency: rapid eustatic fluctuations, energetic tsunamis, storm waves and surges, tides and good weather wind waves. Coastal environments are classified in low, sedimentary coasts, including beaches, dunes, barrier islands, lagoons, salt marshes and river mouths, and high, rocky coasts. Management of coastal zones needs a deep knowledge of all the processes involved at the littoral, especially at the local scale, since coastal processes vary rapidly alongshore. At present the integrated coastal management intends to involve different socioeconomic sectors interested in the occupation and use of coasts. Coastal management must include the adaptation of human activities to the natural processes and associated coastal hazards and the protection of coastal values, both of natural and historical-cultural character. Public administrations at different levels should consider the knowledge of the coastal processes at different scales and their potential interaction with human activities in order to design laws and regulations accordingly.

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Section: Low Sedimentary Coasts: Barrier Islands Lagoons Salt Marshes...mentioning

confidence: 99%

Untitled

2022

CIG

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Consejo Editorial / Editorial Board is a scienti ronmental sciences (Hydrology, Ecology, Climatology). Interdisciplinary studies with Human Geography are also welcome. The peer review and publication of articles in Cuadernos de Investigación Geográfica is free of Since 2015 has been included in the Emerging Sources Citation Index (ESCI) of Clarivate Analytics, a new edition of the Web of Science, Geography (Physical) mental Sciences, and Earth and Planetary Sciences.

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Vegetation interactions with geotechnical properties and erodibility of salt marsh sediments

Cited by 17 publications

References 51 publications

Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense

Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense

The complexity of studying coasts: From forms and processes to management

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