Consequence Estimation for the Herbert Hoover Dike Dam Safety Modification Study Risk Assessment

摘要

Although a dam failure can have many types of severe consequences, including economic, social, cultural, and environmental, the primary objective of the USACE Dam Safety program is to manage the potential loss of life risk to the downstream public. USACE considers potential life loss separately from economic and other consequences. Given the generally low likelihood of failure for the majority of dams, it is often difficult to justify dam safety modifications based on economic risk (cost/benefit) alone. Yet, the public may still be at higher risk than society is typically willing to tolerate. USACE recently completed a baseline risk assessment for Herbert Hoover Dike (HHD), which included an assessment of the full range of load conditions, system response to those loads, and potential consequences of failure scenarios. Due to the complex nature of the flood characteristics and areas at risk from potential failure of HHD, a state-of-the-art simulation model called LIFESim was applied to estimate life loss associated with potential failure of the dike. LIFESim is a modular, spatially-distributed, dynamic simulation system for estimating potential life loss from natural and dam and levee failure floods that explicitly considers the primary factors that contribute to life loss in a flood situation. LIFESim can be used to provide inputs for dam safety risk assessment and to explore options for improving the effectiveness of a dam owner's emergency plans or a local authority's response plans. LIFESim is the U.S. Army Corps of Engineers (USACE) most rigorous approach for estimating potential loss of life due to dam failure. Although not the primary decision metric for dam safety investments within USACE, economic impacts are an important consideration in the decision making process. For the HHD assessment, direct economic damages, including urban and agricultural damages, were computed using the Hydrologic Engineering Center's Flood Impact Analysis (HEC-FIA) program. Additional economic impacts, including lost benefits, were also computed.