Uncertainty analysis of risk-based flood safety standards in the Netherlands through a scenario-based approach

Flood risk quantification is a complex process involving a chain of models. The approach contains many uncertainties which accumulate in the calculated flood risk. Risk-based flood safety standards are therefore prone to large uncertainty. This study aims to quantify the uncertainty of risk-based flood safety standards for a Dutch riverine case study. Through a systematic approach using expert elicitation, the key uncertainty sources in the Dutch safety standard derivation are identified. Uncertainty magnitudes are quantified for five main sources of uncertainty, after which these uncertainties are propagated through the model chain in a scenario analysis to derive flood safety standards. The results show that the Dutch risk-based flood safety standards are highly uncertain given the relative uncertainty bandwidth of 70%. The flood safety standards are found to be most sensitive to damage function and evacuation uncertainty. Also, we show that the impact of uncertainty strongly depends on local characteristics.