The Fuzzy Logic Paradigm of Risk Analysis

The fuzzy logic formulation of risk analysis is presented with application to a flood risk management case. If uncertainty in any element of risk analysis (exposure, resistance, and consequences) is expressed as a fuzzy set, the corresponding risk will also be calculated as a fuzzy set. The probabilistic formulation of risk analysis has several difficulties, including: the management of the low-probability/high-consequence case, the selection of the probability models, the scarcity of statistically meaningful data, the uncertainty of the consequence functions, and the covariances involved. Fuzzy logic formulation, as an alternative to statistical methods to define uncertainties, is applicable when all these difficulties must be dealt with simultaneously. A short review of the application of fuzzy logic illustrates the versatility of this approach. A simplified flood risk management example illustrates a case where probabilistic and fuzzy uncertainties are involved in exposure, resistance, and consequences; economic and ecological consequences are considered, and a tradeoff analysis can identify the preferable action.