Probabilistic safety assessment of multi-functional flood defences

The state of the art of flood defence design and assessment shows that the most common adaptation measures for coping with the uncertainties associated with climate change often involve an increase in the size of these water-retaining structures. The shortage of habitable areas in the deltaic zones and the required increase in dimensions gave birth to the multifunctional flood defence concept. The main idea behind the multifunctional flood defences is that the extra space that results from an almost inevitable increase in dimensions can be exploited by including additional non-water retaining functions such as commercial, recreational, ecological and habitational space. The inclusion of these new functions will also allow these defences to be financially feasible as their marginal cost reduces due to the expected benefits from the additional function allocation. The addition of functions will require structural embedments for connecting them to the transport, sewage, water supply, and electricity networks. Flood defences are exposed to deterioration processes known as “failure mechanisms” which may be triggered during flood events. The embedment of hard structures derived from the connecting requirements to the different infrastructure networks will have an impact on these processes and their frequency of occurrence. The present work aimed to quantify these frequency changes (Failure probabilities) by combining detailed physical modeling and emulation techniques so that the derived effects from structural embedments are also included during the probabilistic safety assessment of flood defences.