System-Wide Application of Risk Analysis Tools Report

DAVIS, CA — June 18, 2009. IWR’s Hydrologic Engineering Center (IWR-HEC) released “Documentation and Demonstration of a Process for Risk Analysis of Proposed Modifications to the Sacramento River Flood Control Project (SRFCP) Levees," Project Report 71. The report documents how risk analysis methodologies can be applied to identify potential system-wide hydraulic impacts resulting from modifications to the SRFCP.

This effort demonstrated that existing risk analysis tools can be applied in a systems context to reveal responses in one region of a system from perturbations to another region. This process for the evaluation of proposed modifications to the SRFCP is expected to increase understanding of the potential risk inherent in proposed modification alternatives.

Another objective of this exercise was to understand more fully what is required to advance the current methods and tools for risk management assessments. Actions for Change (AFC) Theme 2 (Risk Informed Decision Making) emphasizes integrated risk management and requires the U.S. Army Corps of Engineers (USACE) to use risk and reliability concepts in planning, design, construction, operations and major maintenance and to improve its review of completed works program by including an assessment component with the goal of ensuring safe, reliable and resilient infrastructure. A major goal of Theme 2 is to develop methods, tools and guidance for performing and using risk and reliability assessments that match the complexity and frequency of the assessments. Actions for Change Theme 2 provided a significant portion of the funding for this effort.

Results from the risk analysis methods described were compared against results derived from deterministic analysis methods for illustrative purposes. The example application illustrated the complexities and effort required in conducting a risk analysis. The report is available on the HEC web site in the Project Reports section as Project Report 71 (PR-71) at http://www.hec.usace.army.mil/publications/ProjectReports/PR-71.pdf (pdf, 4.91 MB) and is also part of IWR’s electronic Library.

More about Risk Analysis

It is important to note that even though this study was meant to define how to perform risk analysis within a systems context, USACE policy for use of risk analysis is not new. It was first issued in March 1996 and updated in January 2006. USACE policy, as stated in ER 1105-2-101, "Risk Analysis for Flood Damage Reduction Studies" (USACE, 2006a), requires the use of risk analysis in planning flood risk management studies and its results are to be documented in principal decision documents. The goal of the policy is a comprehensive approach in which the key variables, parameters, and components of flood risk management studies are subject to probabilistic analysis.

More about the Report

Conception, development and implementation of this process were a team effort. Dr. David Moser, as National Lead for AFC Theme 2, led the support for the project. The impetus behind the effort was provided by the Commander of the South Pacific Division Commander, General John R. McMahon. The initial design and concepts of the methodology were performed by Messrs. Christopher Dunn, Director, and Michael Deering, Chief, Water Resource Systems Division, of the Hydrologic Engineering Center. Execution of the methodology and procedures and the conduct of impact analysis were performed by WEST Consultants, Inc. Project oversight and product review was provided by South Pacific Division and Sacramento District staff. The State of California Department of Water Resources and the Sacramento Area Flood Control Agency provided project coordination, product review and local insights to the system and proposed system modifications.

Learn more about: