Articles | Volume 15, issue 7
https://doi.org/10.5194/nhess-15-1659-2015
https://doi.org/10.5194/nhess-15-1659-2015
Research article
 | 
30 Jul 2015
Research article |  | 30 Jul 2015

Role of intertidal wetlands for tidal and storm tide attenuation along a confined estuary: a model study

S. Smolders, Y. Plancke, S. Ides, P. Meire, and S. Temmerman

Abstract. Coastal lowlands and estuaries are subjected to increasing flood risks during storm surges due to global and regional changes. Tidal wetlands are increasingly valued as effective natural buffers for storm surges by dissipating wave energy and providing flood water storage. While previous studies focused on flood wave attenuation within and behind wetlands, this study focuses on the effects of estuarine wetland properties on the attenuation of a storm tide that propagates along the length of an estuary. Wetland properties including elevation, surface area, and location within the estuary were investigated using a numerical model of the Scheldt estuary (Belgium, SW Netherlands). For a spring tide lower wetland elevations result in more attenuation of high water levels along the estuary, while for a higher storm tide higher elevations provide more attenuation compared to lower wetland elevations. For spring and storm tide a larger wetland surface area results in a better attenuation along the estuary up to a threshold wetland size for which larger wetlands do not further contribute to more attenuation. Finally a wetland of the same size and elevation, but located more upstream in the estuary, can store a larger proportion of the local flood volume and therefore has a larger attenuating effect on upstream high water levels. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.

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Short summary
Within a confined estuary, a large wetland can play an important role in storm surge mitigation. By use of a numerical model the effects of different wetland sizes, wetland elevations and wetland locations along the estuary on storm surge attenuation along the estuary were investigated. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.
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