Rationality in flood risk management: the limitations of probabilistic risk assessment in the design and selection of flood protection strategies

The introduction of new flood protection strategies prompts the need for a general framework for evaluating these strategies. The focus of this paper is on the rationality in selecting between flood protection strategies, more particularly on the question to what extent risk‐based design and probabilistic risk assessment (PRA) can provide a general framework for rational evaluation of different strategies. On the basis of Arrow's impossibility theorem and the standard literature on cost–benefit analysis, the limitations of risk‐based design and PRA are discussed. Applied to the context of flood risk management, it is shown that the problem of selecting between different flood protection strategies is susceptible to Arrow's impossibility theorem, which makes risk‐based design seem less suitable as a generally applicable procedure. The incommensurability of criteria in the selection of flood protection strategies is related to the uncertainties pertaining to the different flood protection strategies. When selecting between strategies, risk‐based design should therefore be complemented with other decision tools.