Hierarchical decision making for flood risk reduction

River flood events often cause large economic damages and casualties requiring stakeholders to manage flood risk. In flood prone areas, flood risk management can be achieved through a series hierarchically integrated protection structures, which together form a hierarchical flood protection system. In current
practice, structures are often optimized individually without considering benefits of having a hierarchy of protection structures. It is here argued, that the joint consideration of hierarchically integrated protection structures is beneficial. A hierarchical decision model is utilized to analyze and compare the benefit of large upstream protection structures and local downstream protection structures in regard to epistemic uncertainty parameters. Results suggest that epistemic uncertainty influences the outcome of the decision model and that, depending on the magnitude of epistemic uncertainty the hierarchical level on which risk reducing measures are most beneficial might change.