Assessment of the Bureau of Reclamation's Security Program (2008) / Chapter Skim
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Appendix C: Two Approaches to Risk Assessment for Dams
Appendix C: Two Approaches to Risk Assessment for Dams
Pages 120-128
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From page 120... ...
It is in this factor that the risk assessment for terrorist hazard differs most from natural hazards, for unlike natural hazards such as earthquake and flood for which the history of independent events is well-documented, the history of terrorist events is brief. As a substitute for quantitative knowledge of recurrence intervals of earthquakes or floods, expressible in probabilistic terms, we must work with relative likelihood of occurrence.
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From page 121... ...
Input to this factor comes from the Bureau, from the water and power districts, and from public safety officials. Following a well-established technology for natural hazards risk assessment, these factors are combined in the form of a triple product to calculate a quantitative risk index as follows: Risk = O × V × I This triple-product approach is described in Recommendations for Bridge and Tunnel Security (DOT, 2003)
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From page 122... ...
Quantifying risk in this manner allows for cost-benefit comparisons of alternative mitigation options. The benefit of each mitigation option is the reduction in the quantified risk for one or more dam component-threat pairs given the mitigation measures in place.
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From page 123... ...
14.00 12.00 10.00 Facility Risk Score 8.00 Gravity Dam B Buttress Dam A Gravity Dam A Buttress Dam B Arch Dam A FIGURE C-2 Quantification of risk for the hypothetical Gravity Dam A compared with the risks for other hypothetical dams. 123 Figure C-2
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From page 124... ...
124 12.00 10.00 8.00 Facility Risk Score 6.00 Pre- Powerhouse Powerhouse Outlet Upstream Powerhouse Abutments Mitigation A B System Face C A&B FIGURE C-3 Cost and benefit (reduction in risk) of six mitigation actions at hypothetical Gravity Dam A
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From page 125... ...
• At the asset level, a survey of an asset's mission-critical elements coupled with knowledge of the consequences of disruption, physical and security vulnerabilities to a wide range of hazards and threats, and asset attractiveness provides insight into actions an asset owner can take to reduce an asset's overall risk exposure. • The total risk associated with a portfolio or system of assets (such as those associated with a region, a jurisdiction, or an infrastructure sector)
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From page 126... ...
that systematically identifies hazard and threat scenarios that are relevant to the region or asset of interest; assesses the losses associated with each of these scenarios, allowing for consequence-based screening; assigns a probability of success; assesses the annual occurrence rate for each scenario; and provides results suitable for benefit-cost analysis. CAPRA produces actionable risk assessments that inform a stakeholder of potential risks through custom-tailored risk communication reports and offers suggestions on what to do about them.
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From page 127... ...
Consequence Security Hazard Risk Informed Scenario Benefit/Cost and Criticality Vulnerability Likelihood Decisions Identification Analysis Assessment Assessment Assessment FIGURE C-5 Phases of the CAPRA process. Figure C-5 127
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From page 128... ...
2005. Risk Assessment: A How-To Guide to Mitigate Potential Terrorist Attacks Against Buildings.
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