COASTAL LEVEE CONSEQUENCE ASSESSMENT TO SUPPORT RISK-INFORMED DECISION MAKING IN DESIGN

A key understanding of any levee system is to accurately estimate the residual flood risk that remains for the population after a levee project is in place and to quantify the portion of the risk related to overtopping (non-breach risk) compared to the risk related to levee performance (incremental risk). The incremental risk is a product of the frequency of the hazard, the performance of the system given the hazard, and the resulting consequences of the system These risks are present for any dam or levee project, to include Coastal Storm Risk Management (CSRM) systems of levees, dunes, floodwalls, seawalls, gates, and many other features. In order to make resilient, risk-based decisions for coastal levee designs, design teams need to have a thorough understanding of the coastal hazards, associated breach and non-breach consequences, and how the design performance affects the incremental and residual risks. This paper discusses the linkages between high-fidelity understandings of each of these three aspects – hazards, consequences, and performance – in a way to make smart, risk-informed decisions for design.