This project is under preparation
Project outcome
Probabilistic framework to compare and assess multifunctional flood defences and guidelines for their implementation.
The dike at Oterdum (NL), showing the range of (unusual) objects and functions that can be encountered on/near a flood defence. (source: Photo by Richard Marijnissen)
Motivation and practical challenge
Flood defences have the potential to be integrated with many other function (e.g. nature, recreation, transport, housing etc.). A shared-use of the flood defence often implies a robust design to guarantee safety. Some functions impose new restrictions on the flood defence, some elements like natural foreshores can contribute to reducing flood risk by damping wave energy, while other functions like the grazing of sheep might hardly affect the functioning of the defence at all.
Research challenge
The objective of this research is to gain more insight in the effects of the multifunctional use of flood defences on flood risk using the new probabilistic risk approach recently adopted in the Netherlands.
Innovative components
My research integrates already existing research in flood protection, risk management and (eco) engineering into a risk assessment framework. First a framework to assess the risk of Multifunctional Flood Defences (MFDs) was developed using existing assessment procedures as a basis.
Now we are looking at the two innovative case-studies to apply the concepts of the framework: the Wide Green Dike, and the Double Dike. How are additional functions (e.g. clay mining and marshes) supported by the design of the dike, and what risks or synergies do these functions provide for the dike?
In the final step the initial framework, as well as the case-studies, are evaluated. A framework will be provided for integration of additional functions within the new risk standards.
Relevant for whom and where?
The results are beneficial for users involved in designing, maintaining, assessing and drafting policies for flood defences within the new risk-based approach. All-Risk is supported by the water-boards in the north of the Netherlands who are keen to integrate the results into current and future dike reinforcement projects.
Progress and practical application
Conservative estimates of multifunctional flood defences (MFDs) lead to a systematic underestimation of the reliability of these dikes. Instead, the probability of different scenarios in which elements affect the flood defence should be incorporated to evaluate the safety of a flood defence. In some situations, the probability of a dike failure may turn out to be 100 times stronger than would conservatively be estimated. Not only in the present, but also for the future MFD can be more adaptable. Natural foreshores accrete overtime and partially mitigate the effects of future sea-level rise on the flood defence as well as provide a source of material for future reinforcements. Recognising the potential of MFDs is vital to efficiently strengthen the Dutch flood defences for the future.
Status for day-to-day practice
Numerous combinations of functions can be integrated in a multifunctional flood defence system. The goal of this project is to provide a proper framework for recognising the risks and synergies of different uses with flood protection.
Next steps
In the next steps we will continue to research promising multifunctional dike concepts.
Last modified: 22/04/2020
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User group
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