Risk Analysis of Proposed Modifications to Sacramento River Levees (CA)
The Sacramento River Flood Control Project (SRFCP) is a large system of regulated and unregulated inflows, watercourses, bypasses, hydraulic structures, and tidal influences. Recently, the state of California passed two bond measures that provide approximately $5 billion over the next ten years for improvements to help manage flood risk. Much of this money will be spent in the Central Valley for improvements on the State-Federal levee system. Before the State and local agencies can proceed with these modifications, the Corps must approve them under 33 United State Code (U.S.C.) Section 408 permitting process to assure that such projects will not result in significant, unmitigated impacts to the flood protection system. Evaluating potential system-wide hydraulic impacts will be a major element of the Section 408 permit review and approval process. The Corps plans to complete this process using risk analysis methodologies.

WEST Consultants, Inc. (WEST) was contracted by the U.S. Army Corps of Engineers, Hydrologic Engineering Center (HEC) to help define and conduct a process for applying risk analysis methodologies to identify potential system-wide hydraulic impacts resulting from alterations and modifications to the SRFCP. The risk analysis process was defined using the guidance provided in EM 1110-2-1619, Risk-Based Analysis for Flood Damage Reduction Studies, (USACE, 1996) and the policies established in ER 1105-2-101, Risk Analysis for Flood Damage Reduction Studies, (USACE, 2006). As an example, WEST applied the process to illustrate the evaluation of potential system-wide impacts associated with several Early Implementation Projects (EIP) proposed for the SRFCP. Results from the risk analysis methods were also compared against results derived from deterministic analysis methods. The analysis process and results of the example impact evaluation were documented in a technical report.