Applying Risk Analyses to Early Design Phases of Dam and Levee Projects

摘要

The dam and levee safety industry has seen an increasing trend in the use of risk analyses to help inform programmatic decisions. That trend continues not only in the number of agencies adopting a risk-informed approach to assess and manage a portfolio of existing structures, but also in the breadth in which risk analyses are applied for decision making. The U.S. Department of the Interior, Bureau of Reclamation (Reclamation) pioneered the systematic use of dam safety risk analysis in the U.S. through the 1980s and 1990s to more appropriately prioritize resources and to better understand the risk posed by its dams. The Federal Energy Regulatory Commission (FERC) and the U.S. Army Corps of Engineers (USACE) began using a risk-informed decision-making process in their dam safety programs in the 2000s. Over the past decade, a number of state dam safety agencies and dam owner organizations have also begun to introduce risk methodologies into their dam safety programs. Risk analyses have primarily been used to evaluate the severity and urgency of safety deficiencies in the physical condition, design, or operation of a dam; to prioritize risk reduction activities; and to make programmatic decisions associated with resource allocation. The increasing frequency of applying risk analysis has resulted in the dam and levee safety community recognizing the many ways these projects can fail and the consequences of those failures. That same understanding can be applied to the design of dam and levee projects early in the process to evaluate the vulnerabilities and risks of various design alternatives. Risk analyses provide a framework for technical reviews of early-stage designs and can also be used to evaluate life cycle, maintenance, operation, and construction issues. Risk analyses are also being used to support the permitting process by providing a framework to justify the selection of credible failure scenarios to be evaluated in permitting applications. This paper presents the use of risk analyses in the early design stages of dam and levee greenfield and rehabilitation projects, including presenting the benefits, pitfalls, and appropriateness of current methodologies as applied to new projects.