Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense
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 w...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-07-01
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| Series: | Frontiers in Marine Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmars.2022.920480/full |
| _version_ | 1818161638742687744 |
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| author | Ken Schoutens Marte Stoorvogel Mario van den Berg Kim van den Hoven Tjeerd J. Bouma Tjeerd J. Bouma Stefan Aarninkhof Peter M. J. Herman Jantsje M. van Loon-Steensma Jantsje M. van Loon-Steensma Patrick Meire Jonas Schoelynck Patrik Peeters Stijn Temmerman |
| author_facet | Ken Schoutens Marte Stoorvogel Mario van den Berg Kim van den Hoven Tjeerd J. Bouma Tjeerd J. Bouma Stefan Aarninkhof Peter M. J. Herman Jantsje M. van Loon-Steensma Jantsje M. van Loon-Steensma Patrick Meire Jonas Schoelynck Patrik Peeters Stijn Temmerman |
| author_sort | Ken Schoutens |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-11T16:20:57Z |
| format | Article |
| id | doaj.art-cb08367292fd4b849ab73bf993c94ba3 |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-12-11T16:20:57Z |
| publishDate | 2022-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-cb08367292fd4b849ab73bf993c94ba32022-12-22T00:58:51ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452022-07-01910.3389/fmars.2022.920480920480Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood DefenseKen Schoutens0Marte Stoorvogel1Mario van den Berg2Kim van den Hoven3Tjeerd J. Bouma4Tjeerd J. Bouma5Stefan Aarninkhof6Peter M. J. Herman7Jantsje M. van Loon-Steensma8Jantsje M. van Loon-Steensma9Patrick Meire10Jonas Schoelynck11Patrik Peeters12Stijn Temmerman13ECOSPHERE, Department of Biology, University of Antwerp, Antwerp, BelgiumDepartment of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research, Yerseke, NetherlandsHydraulic Engineering Department, Delft University of Technology, Delft, NetherlandsWater Systems and Global Change Group, Wageningen University & Research, Wageningen, NetherlandsDepartment of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research, Yerseke, NetherlandsDepartment of Physical Geography, Utrecht University, Utrecht, NetherlandsHydraulic Engineering Department, Delft University of Technology, Delft, NetherlandsHydraulic Engineering Department, Delft University of Technology, Delft, NetherlandsWater Systems and Global Change Group, Wageningen University & Research, Wageningen, Netherlandsvan Hall Larenstein, University of Applied Sciences, Velp, NetherlandsECOSPHERE, Department of Biology, University of Antwerp, Antwerp, BelgiumECOSPHERE, Department of Biology, University of Antwerp, Antwerp, BelgiumFlanders Hydraulics Research, Antwerp, BelgiumECOSPHERE, Department of Biology, University of Antwerp, Antwerp, BelgiumNature-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.https://www.frontiersin.org/articles/10.3389/fmars.2022.920480/fullsediment stabilityflow velocityflood riskdike breachnature-based adaptation |
| spellingShingle | Ken Schoutens Marte Stoorvogel Mario van den Berg Kim van den Hoven Tjeerd J. Bouma Tjeerd J. Bouma Stefan Aarninkhof Peter M. J. Herman Jantsje M. van Loon-Steensma Jantsje M. van Loon-Steensma Patrick Meire Jonas Schoelynck Patrik Peeters Stijn Temmerman Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense Frontiers in Marine Science sediment stability flow velocity flood risk dike breach nature-based adaptation |
| title | Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense |
| title_full | Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense |
| title_fullStr | Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense |
| title_full_unstemmed | Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense |
| title_short | Stability of a Tidal Marsh Under Very High Flow Velocities and Implications for Nature-Based Flood Defense |
| title_sort | stability of a tidal marsh under very high flow velocities and implications for nature based flood defense |
| topic | sediment stability flow velocity flood risk dike breach nature-based adaptation |
| url | https://www.frontiersin.org/articles/10.3389/fmars.2022.920480/full |
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