Webinar: Risk Assessment for Levee Projects

The USACE has been conducting economic risk analyses for evaluating benefit cost ratios for levee projects since the 1960s. With a new focus on life safety, these same analytical techniques are now being used to evaluate priorities for infrastructure investments and required design reliability to achieve various goals, including National Economic Development and life safety risk reduction. This webinar will look at how the USACE is integrating traditional probabilistic levee fragility assessments, as described in ETL 1110-2-556 (Risk-Based Analysis in Geotechnical Engineering for Support of Planning Studies, 1999), with event-tree based system-response / fragility curve development process described in the joint USBR/USACE Best Practices in Dam and Levee Risk Analysis (2015) to evaluate levee system risk and risk reduction alternatives.

Key Takeaways:

1. The USACE is moving towards risk-informed evaluation and design of levee systems and improvements.
2. In USACE quantitative risk analyses, levee performance is evaluated using potential failure mode and event tree analysis methods.
3. Event tree nodal probabilities can be estimated using a variety of techniques, including probablisitic, emperical and expert elicitation.
4. Levees must be considered from a "system" approach, looking concurrently at all potential failure modes when evaluating risk and risk reduction.
5. To efficiently reduce risk by structural means, levee prior to overtopping reliability (akin to levee “width”) and levee overtopping reliability (akin to levee “height”) must be improved commensurately.