Integrated Risk Assessment for the Natomas Basin (California) Analysis of Loss of Life and Emergency Management for Floods

Abstract

This article assesses the risk to life for the Natomas Basin, a low-lying, rapidly urbanizing region in the Sacramento-San Joaquin Delta in California. Using an empirical method, the loss of life is determined for a flood (high water), seismic, and sunny-day levee breach scenario. The analysis indicated that more than 1,000 fatalities may occur in the flood scenario and that there is a high flood risk compared with similar systems (e.g., dams in the United States and flood-prone areas in the Netherlands). Findings show that the risk to life highly depends on evacuation effectiveness. The evacuation and emergency management (EEM) system was further analyzed through interviews with regional emergency managers and training exercise evaluation reports. Using an analytic framework, critical factors that affect the EEM system performance and reliability were identified. Results indicate a need to assess the EEM system performance to improve preparedness and reduce the risk to life. Findings from the investigation contribute to more integrated risk analyses of both the technical and management components for engineered systems.