Quantitative Assessment of Uncertainties and Sensitivities in the Estimation of Life Loss Due to the Instantaneous Break of a Hypothetical Dam in Switzerland

Abstract

High safety standards of operators and regulators for dams in Switzerland require periodic assessments of risk mitigation measures at dams. Therefore, risk assessments need to include the estimation of life loss (LL) due to a potential dam break. This study demonstrated the benefits of applying the HEC-LIFESim software for modelling LL due to the instantaneous break of a hypothetical dam in Switzerland. HEC-LIFESim overcomes limitations of empirical methods by modelling evacuation and warning processes. Furthermore, for credible LL estimates, metamodelling was used to quantify uncertainty in model parameters. Polynomial chaos expansion (PCE) was applied to approximate the LL model of HEC-LIFESim using only 550 runs. Uncertainty in the model inputs was propagated through the metamodel to quantify uncertainty in the LL estimates. Finally, a global sensitivity analysis was performed by calculating Sobol’ and Borgonovo indices. The results demonstrate that the three-parameter population in a locality within all considered localities, fatality rate in the chance zone, and warning issuance delay contributed most to the variability of the LL estimates. The application of the proposed methodology can support risk management by providing detailed and accurate risk measures and helping in prioritizing safety measures to be considered and implemented.