A framework for uncertainty analysis in flood risk management decisions

Abstract Modern flood risk management involves responding sustainably to flood risk with portfolios of structural and non‐structural measures. Under these circumstances of multi‐attribute choice between portfolios of options, the motivation for uncertainty analysis becomes more compelling than ever. Uncertainty analysis is required in order to understand the implications for decision makers of limited data, model uncertainties, changes in the flooding system over the long term, incommensurate scales of appraisal and potentially conflicting decision objectives. In recognition of the importance of uncertainty analysis as an integral aspect of sustainable flood risk management, a new framework for uncertainty analysis within flood risk management decisions has been established. The proliferation of methods for uncertainty analysis can be placed within the coherent framework. As well as estimating the amount of uncertainty associated with key decision variables, the framework supports the decision making process by identifying the most influential sources of uncertainty, and the implications of uncertainty for the preference ordering between options. The challenges posed by severe uncertainty about the potential for long term changes in the flooding system are discussed and robustness analysis is advocated in response to these uncertainties.