Making Levee Safety Decisions in the Context of Flood Risk Management

Levees provide vital flood risk reduction in the United States and throughout the world. It is important to understand that levees reduce, but do not eliminate, flood risk. Levees are just one component of a holistic flood risk management strategy, which typically includes a combination of structural and nonstructural approaches. Decisions related to all aspects of the levee life cycle, from planning to removal, should be made in the context of overall flood risk management strategies. Differences between levee risk management and flood risk management actions and decisions should be well understood, with clear goals and objectives to inform risk management approaches that are aligned with both the flood risk reduction provided by the levee and the risks posed by the levee.

This article describes the relationship between flood risk and levee risk; explains the often-confusing concepts such as residual risk, non-breach risk, breach prior to overtopping, and overtopping with and without a breach; and discusses how these terms are used to properly characterize the flood risk reduction benefits provided by a levee. The authors acknowledge that there are other terms used to describe these concepts, both in the United States and internationally, which can sometimes make the understanding of these concepts more difficult.