A Decision Tree for a Cost-Benefit Analysis on Flood Risk Management with Uncertain Funding

River floods generated relevant disasters worldwide and motivated the need to set up Flood Risk Management plans. According to the European Directive 2007/60/CE, the flood-risk evaluation should include a cost–benefit analysis on a long-term planning horizon. However, the cost-benefit analysis is typically made under the deterministic assumption to know which uncertain events will be observed in the planning horizon and a priori establishes which actions will be taken throughout this long time interval. Clearly, this myopic policy is not adequate in the domain of Flood Risk Management, in which most of the data are uncertain when the cost-benefit analysis is made and decisions should dynamically respond to the observation of uncertain parameters. In order to face the former challenges, this paper shows how the cost-benefit analysis can be supported by a decision tree for structuring and analyzing decisions in the face of uncertainty on the available funding. Finally, the paper reports some outcomes in the experimentation on the Coghinas Basin (Sardinia, Italy).