Thesis defence V. Vuik: flood risk

27 March 2019 10:00 - Location: Aula, TU Delft - By: webredactie

Building Safety with Nature. Salt Marshes for Flood Risk Reduction. Promotor: S.N. Jonkman (CiTG).

This dissertation investigates the functioning and reliability of nature-based solutions for flood risk reduction. Vegetated foreshores, such as salt marshes, reed swamps and mangrove forests can reduce the wave loads on coastal dikes, which allows for making them less high and strong. Field measurements in the Western Scheldt and Wadden Sea (the Netherlands) have provided new insights in wave damping over salt marshes during storms. Waves reduce in height due to wave breaking on the elevated foreshore, and vegetation induces additional wave attenuation. Subsequently, a formula was developed to predict the wave forces that plant stems can withstand before they break or fold. This formula indicates that salt marsh vegetation will experience large-scale stem breakage during the severe storms for which dikes are usually built. Modules describing physical processes on the foreshore were coupled to modules describing dike failure mechanisms. Ultimately, a failure probability was computed for a dike with vegetated foreshore, by applying probabilistic methods. At suitable locations, realization of a foreshore is more cost-effective than dike heightening, e.g. in countries with a relatively low level of protection, or at locations with a limited range of storm surge levels. This research is expected to facilitate more frequent application of vegetated foreshores and similar nature-based solutions, since their effectiveness and life cycle costs can now straightforwardly be compared to more traditional engineering solutions.

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For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence.