When specifying the event tree, the most challenging task seems to be the specification of the flood event probabilities (exceedance probability) for future climate. Although some of the experts were familiar with flood events and their hydrological characteristics they found it hard to determine the return time for future floods.
The branching probabilities were felt easier to specify as changes in the technical and/or operational traits of the barrier functions are more tangible.
The experts stressed the importance of having a wide range of technical expertise available in the elicitation process. Sector managers’ domains are usually at a higher level than what is appropriate for eliciting branching probabilities of operational outcomes.