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Early Planning Can Create Postflooding Resiliency

Severely damaged levee on the east side of the Industrial Canal in New Orleans
The levee on the east side of the Industrial Canal in New Orleans was severely damaged by Hurricane Katrina in 2005. A new report from the National Research Council recommends that engineers, builders, operators, and regulators work together to assess the risk to communities from dam and levees breaks and to communicate those risks as well as community resiliency and recovery strategies. Photo by Jocelyn Augustino/FEMA

A new report published by the National Research Council maps out methods for dam and levee professionals to help communities become resilient in the face of dam and levee failures.

October 16, 2012—The National Research Council recently released a new report, “Dam and Levee Safety and Community Resilience: A Vision for Future Practice,” that maps out how dam and levee safety professionals can become part of their communities’ broader resiliency efforts, and how state- and federal-level professionals can assist communities in the face of widespread flooding caused by significant dam and levee failures. Such flooding is an ongoing problem, despite such regulatory efforts as the National Dam Safety Program, and nearly 1,500 dam failures have occurred in the United States since the 19th century, the report notes. While levee failures have not been tracked as carefully, the most recent and well-known large-scale levee failure occurred just seven years ago in New Orleans as a result of Hurricane Katrina.

There are three key features of a resilient community, according to the report: the ability to assess and minimize potential threats; the ability to use existing social and physical infrastructures to effectively mitigate, prepare for, respond to, and recover from disasters; and the capacity to adapt and learn from change and adversity.

The authors of the report assert that in order to create a community that is resilient in the face of flooding caused by a dam or levee failures, it is crucial to have buy-in from dam and levee professionals—including civil and structural engineers—in advance of a flood. And while public communications regarding hazard preparation, risks, and response and recovery planning have been common—and effective—within the earthquake engineering community, engineers involved in the design and construction of dams and levees may be new to the process. And basing designs on risks rather than standards would also require a shift in thinking, the report states.

“Risk-informed approaches are practices based on the information gathered through risk assessment and are not regularly applied in many dam and levee safety programs,” the report states. “Engineering design and operating procedures for dams and levees are primarily standards-based—for example, based on a defined level of infrastructure performance given a specific hazard.” But standards-based approaches do not explicitly quantify performance uncertainties or risks to communities, the report says. Risk-based approaches, however, “take into account the likelihood and consequences of different failure scenarios and can provide designers and operators more information with which to make technical decisions that improve safety.”

The communities themselves would also benefit from information on the nature of potential failures, risks, and consequences, the report states—even if the news isn’t always good. “Resources can then be allocated more strategically based on the consequences for different community or stakeholder groups,” the report says.

But engineers, builders, and operators aren’t in this alone; flood risks must be managed collaboratively, the report says. Local-level dam and levee officials need to embrace their responsibilities for risk management, an effort that the federal government can help with using emergency-management tools that already exist, the report points out. Once risk-management efforts become institutionalized and a normal part of a community’s efforts, frequent and collective evaluation of the processes can take place to ensure that they are functioning properly, according to the report.

“Postdisaster recovery efforts require detailed knowledge of population and activities, knowledge that is necessarily developed well in advance in the course of building resilience,” said John J. Boland, Ph.D., P.E., a professor emeritus at The Johns Hopkins University and the chair of the National Research Council’s committee on integrating dam and levee safety and community resilience, the lead committee on the report. Boland wrote in response to written questions submitted by Civil Engineering online.

“Possibly the most important argument for a resilient community is the ability to reduce vulnerability to property damage and loss of life in the event of a disaster,” Boland said. However, because “building resilience requires the sharing of information and the development of effective communication networks [before a disaster], there are clear benefits even after a disaster: Emergency response efforts are swifter and more effective when all parties are accustomed to collaboration and mutual support.”

According to Boland, community resilience is not a status that can be decreed by the Federal Emergency Management Agency or state regulators, or even by dam or levee owners or operators. “It must be built up within the community, by the community, and in a way that is appropriate to the community,” Boland said. This often requires a shift in the culture of how dam and levee safety professionals and regulators typically work together, he noted, because the process requires “building trust and sharing information between the community at large and the dam and levee safety professionals.”

The bottom line is that in most cases the two groups—dam and levee safety professionals and regulators—must embrace the responsibilities and benefits of community-level collaboration, Boland said.

In addition to the committee noted above, the report was developed by the National Research Council’s committee on geological and geotechnical engineering and the board on earth sciences and resources.



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