supplies, power generation and transmission, communication systems, transportation systems, agricultural resources, and sanitation. Social effects can include psychosocial impacts (e.g., depression), demographic impacts (e.g., in- and outmigration), economic impacts (e.g., business disruption), and political impacts (e.g., mobilization of emergent groups) (Lindell et al., 2006). Such social effects can cause major disturbances on the social and organizational networks that are the core of much of community functioning. Other effects on the proximate community are to be expected. Indirect effects, however, can expand well beyond the local area. The financial effect of flooding, for example, may be national or global as a result of interruptions to commercial supply chains or financial markets (e.g., see A.M. Best, 2012). Failure can cause widespread disruption of normal societal functioning and affect communities, commerce, and individuals.

Because the effects of dam or levee failure on physical and social infrastructures can be broad, a more comprehensive approach to dam and levee safety beyond traditional standards-based and structurally based safety goals is needed. The earthquake-engineering profession has learned through experience that engaging a community in hazard preparedness, risk communication programs, response and recovery planning and training, and formulation of new adaptations can pay large dividends in reducing the short-term and long-term effects of an event (e.g., NRC, 2011b). For example, property damage in the 1994 Northridge, California, earthquake was lower in communities that had stronger hazard mitigation plans and stronger code enforcement efforts than in communities that did not (Burby et al., 1998).

Similar outcomes may be expected as a result of safety and resilience initiatives associated with dams and levees, although the committee recognizes that plans implemented for each type of infrastructure will necessarily be different. Communication and collaboration among all affected before, during, and after a failure—including communication related to flood risks, anticipating and planning for likely events, evacuation planning, and warning—is essential if planning is to make mitigation, preparedness, response and recovery operations, and other long-term adaptations timely and successful. The Federal Emergency Management Agency (FEMA) requested the present study to aid in development of initiatives to help decision makers reduce risk to life and property caused by dam or levee failure—initiatives that take resilience of the community fully into account.

THE COMMITTEE’S TASK

Under the sponsorship of FEMA, the National Research Council convened a panel of experts to consider how dam and levee safety as a concept and a practice can be expanded to promote the core values of FEMA’s mission—to improve community, regional, and national resilience. The committee includes researchers and practitioners who have expertise in dam and levee safety engineering, hydraulic engineering, risk reduction, disaster



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