U.S. Army Corps of Engineers Levee Safety Program

Putting levees in a risk framework

By Charles Dervarics - May 10, 2013

The U.S. Army Corps of Engineers (USACE) St. Louis (Mo.) District replaces two closure structures on the west flank of the Wood River Creek in Illinois, April 24, 2012. Replacing the structures, and the adjacent floodwall, is one feature of USACE’s Wood River Levee reconstruction project to correct design deficiencies and maintain the levee system’s authorized design level (approximately 54 feet on the St. Louis gage). U.S. Army Corps of Engineers photo by Romanda Walker

To answer these questions, USACE is performing screening-level risk assessments on levee systems in its portfolio to be complete by fiscal year 2015. Central to this approach is how USACE quantifies inundation risk associated with three scenarios – breach before overtopping, breach with overtopping, and component malfunction.

The screening-level risk assessment includes a limited engineering assessment of levee system performance-related items such as seepage, erosion, and settlement. This assessment relies on readily available information, such as design, construction, inspection, and historic performance records. This assessment is followed by a consequence analysis (life safety and economic damage) for several ways by which the floodplain could become inundated due to poor levee performance. The screening-level risk assessment concludes with experts interpreting and discussing the outcome of these assessments and associated recommendations.

“We are aggressively moving forward with screening-level risk assessments. We have initiated more than 800, but we have more than 2,000 to go,” Conforti said.

Putting levees in a risk context is a consistent and credible way to prioritize actions especially in a time of constrained resources. USACE plans to use the risk assessment results not only to prioritize areas with high life safety risk for its own levee safety activities, but to communicate the results to levee sponsors and other stakeholders so they can make more informed decisions.

Federal Alignment

Effective partnerships with other federal, state, and local agencies are another USACE priority.

One priority is to work more closely with FEMA, which executes the National Flood Insurance Program. USACE and FEMA have distinct but complementary roles and responsibilities when dealing with levees. Both agencies are working together to make communities more aware of their flood risk through concerted education and outreach efforts. A recently formed USACE/FEMA task force is working on recommendations to better align processes related to levees.

“Our relationship with FEMA is the strongest it’s ever been,” Conforti said. Coordination between the two agencies is now standard practice. Local outreach is particularly important since local government and even private entities may have prime responsibility for the levees.

“We think it’s important that local entities are engaged,” Conforti said.

In this way, the federal government can be a major partner – but not the only one – in assessing and managing U.S. infrastructure. “It’s a shared risk,” said Halpin, “and a shared responsibility.”

This article originally appeared in U.S. Army Corps of Engineers: Building Strong®, Serving the Nation and the Armed Forces 2012-2013 Edition.