Uncertainties in the risk assessment of hydropower dams:state-of-the-art and outlook

Risk assessment of hydropower dams is a topic of great interest for countries withextensive production facilities like Switzerland. Due to the high costs associated tothe detailed simulation of dam failure events, however, traditional approaches toquantify the risk they pose are largely based on the statistical analysis of historicaldata, or on worst-case scenario modelling. In the latter case, the design of suchscenarios is usually based on sometimes contrasting expert opinion or very sparseavailable data. In addition, there exist no unique framework or set of tools to quantitativelyassess the socio-economical consequences of a dam-related flood event.The sparsity of available data, combined with the variability of environmentalconditions (e.g. weather conditions, time of the day etc.) and lack of knowledge onthe failure process (e.g. dam failure mechanisms) create an additional layer of uncertaintythat is not yet properly dealt with in the current risk assessment workflows.This report summarizes the state-of-the-art of risk assessment for hydropowerproduction dams at all levels: from the problem statement itself, to the technicaltools (theoretical and numerical) available for its solution, with a focus on life lossestimation and on the role of uncertainty on the final analysis results.The work for this report was conducted within the project “Risk Governance ofDeep Geothermal and Hydro Energy” of the National Research Programme “EnergyTurnaround”. It is closely coordinated with ongoing activities of the Technology Assessmentgroup at the Paul Scherrer Institute (PSI) in both the National ResearchProgram (NRP) 70 “Energy Turnaround” and the Swiss Competence Center for EnergyResearch (SCCER) “Supply of Electricity” (SoE)