Author(s): Maarten Schoemaker; Wilfred De Kam; Constantijn Steenbergen; Richard Bloekpoel; Matthijs Kok
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Keywords: Intertidal area estuarine nature nature based solutions flood risk flood probability safety standards probabilistic recreation hydraulic structures culvert control gates
Abstract: Waterdunen is a unique intertidal estuarine nature area of 350 ha. It is located along the North Sea, but inland of the primary water defense. By means of a tidal culvert through the primary flood defence, a safe intertidal area could be created inland in which estuarine nature with salt marshes could develop with a total wet area of around 214 ha. This estuarine nature attracts many types of birds, including little egrets, spoonbills, shelducks, black-headed gulls and sandwich terns among others. As the tidal culvert controls the water levels, the intertidal area is safe from flooding, even during strong storms. This allows other types of developments to take place as well, such as the construction of walkways, holiday homes, a testing ground for salty crops and an oyster farm. Many visitors are attracted to the Waterdunen tidal area, giving the local economy a significant boost. The development of Waterdunen had its challenges. In 2017 new safety standards for flood defenses were introduced in the Netherlands. The new safety standards require a full probabilistic approach to estimate the flood probability behind the primary water defenses. Hence, there was a need for a full probabilistic framework to prove that the tidal culvert through the primary water defence will not exceed these new safety standards. With this framework, it could be proven that the original design was exceeding the new safety standards. This meant that adjustments had to be made. These include an electromechanical installation with increased reliability and an improved control system. With these adjustments, the probability of failure of the tidal culvert proved to be within the required safety standards. This extended abstract will elaborate the steps that are taken in this framework. For similar structures the probability of flooding can be estimated in a similar way.
Year: 2025