Historic storms and the hidden value of coastal wetlands for nature-based flood defence

Historic storms and the hidden value of coastal wetlands for nature-based flood defence

Zhu, Zhenchang (Universiteit Utrecht; Guangdong University of Technology; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou); NIOZ Royal Netherlands Institute for Sea Research)
Vuik, V. (TU Delft Coastal Engineering; HKV Lijn in Water)
Visser, P.J. (TU Delft Rivers, Ports, Waterways and Dredging Engineering)
Soens, Tim (Universiteit Antwerpen)
van Wesenbeeck, B (Deltares)
van de Koppel, Johan (Universiteit Utrecht; NIOZ Royal Netherlands Institute for Sea Research)
Jonkman, Sebastiaan N. (TU Delft Hydraulic Structures and Flood Risk)
Temmerman, Stijn (Universiteit Antwerpen)
Bouma, T.J. (NIOZ Royal Netherlands Institute for Sea Research; Universiteit Utrecht)

2020

Global change amplifies coastal flood risks and motivates a paradigm shift towards nature-based coastal defence, where engineered structures are supplemented with coastal wetlands such as saltmarshes. Although experiments and models indicate that such natural defences can attenuate storm waves, there is still limited field evidence on how much they add safety to engineered structures during severe storms. Using well-documented historic data from the 1717 and 1953 flood disasters in Northwest Europe, we show that saltmarshes can reduce both the chance and impact of the breaching of engineered defences. Historic lessons also reveal a key but unrecognized natural flood defence mechanism: saltmarshes lower flood magnitude by confining breach size when engineered defences have failed, which is shown to be highly effective even with long-term sea level rise. These findings provide new insights into the mechanisms and benefits of nature-based mitigation of flood hazards, and should stimulate the development of novel safety designs that smartly harness different natural coastal defence functions.

http://resolver.tudelft.nl/uuid:1abeace8-57aa-40f9-a830-4b15881ba149

https://doi.org/10.1038/s41893-020-0556-z

2020-12-29

Nature Sustainability, 3 (10), 853-862

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

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© 2020 Zhenchang Zhu, V. Vuik, P.J. Visser, Tim Soens, B van Wesenbeeck, Johan van de Koppel, Sebastiaan N. Jonkman, Stijn Temmerman, T.J. Bouma