Evaluation of the impact of risk reduction indicators and epistemic uncertainty in dam safety governance

Large dams are critical infrastructures whose failure could produce high economic and social consequences. For this reason, in recent years, the application of quantitative risk analysis to inform dam safety governance has risen significantly worldwide. This thesis is focused in how computed quantitative risk results can be useful to inform dam safety management. It proposes different methods and metrics to deal with the two key issues identified in this process: how risk results can be managed to prioritize potential investments and how uncertainty should be considered in quantitative risk models to inform decision making. Firstly, it is demonstrated that risk reduction indicators are a useful tool to obtain prioritization sequences of potential safety investments, especially in portfolios with a high number of dams. Different indicators for dam safety are assessed, analyzing their relation with equity and efficiency principles. Secondly, it is proposed to consider explicitly and independently natural and epistemic uncertainty in quantitative risk models for dams, following the recommendations developed by other industries. Specifically, a procedure is developed to separate both types of uncertainty in the fragility analysis for the sliding failure mode of gravity dams. Finally, both issues are combined to propose different metrics that analyze the effect of epistemic uncertainty in the prioritization of investments based on risk results. These metrics allow considering the convenience of conducting additional uncertainty reduction actions, like site tests, surveys or more detailed analysis. Las grandes presas son infraestructuras críticas cuyo fallo puede producir importantes consecuencias económicas y sociales. Por este motivo, en los últimos años la aplicación de técnicas de análisis de riesgos para informar a la gobernanza de la seguridad de presas se ha extendido por todo el mundo. La presente tesis se centra en analizar cómo los resultados calculados de riesgo pueden ser útiles para la toma de decisiones en seguridad de presas. Para ello, se proponen diferentes métodos e indicadores que tratan los dos principales problemas identificados en este proceso: cómo gestionar los resultados de riesgo para priorizar potenciales inversiones en seguridad y cómo debe ser considerada la incertidumbre en los modelos de riesgo para orientar a la toma de decisiones. En primer lugar, se muestra como los indicadores de reducción de riesgo son una herramienta útil y e