Event Tree Principles and Applications for Dam Safety Risk Assessment May 11, 2015 David S. Bowles, Ph.D., P.E., P.H., D.WRE, F.ASCE Since 1978 David and his colleagues have pioneered the development and practical application of risk-informed approaches to dam safety management. They have completed individual and portfolio risk assessments for more than 800 dams in many countries, ranging from screening assessments to detailed assessments with uncertainty analysis. David has assisted with the development of tailored frameworks for dam and levee safety risk management for government and private owners, regulators and professional bodies in many countries. Clients have included Reclamation, USACE, TVA, FERC, BIA, World Bank, WMO, IAEA, EPRI, EU, ANCOLD, CDA, NSW DSC and many major engineering firms. David has served as an expert witness for law suits related to dam and canal failures, reservoir operation and hydropower generation, toxic tort, and urban flooding. David has used event tree risk models to represent a wide variety of failure modes and other conditions that affect the magnitude of consequences in dam safety risk assessments. He has developed software for event tree calculations for the USACE Risk Management Center with features designed specifically for dam safety applications. He has published many papers and reports describing event tree methods and applications, including uncertainty analyses, length effects and multiple impoundment systems such as those at coal ash disposal facilities and tailings mines. Applications have been for hydropower, water supply, mining, nuclear and multi-purpose projects. David has provided training programs on six continents and has authored or reviewed numerous guidance documents for dam safety risk analysis, assessment and management. He has led software development for dam risk analysis (DAMRAE) and life-loss estimation (LIFESim with a simplified version in HEC-RAS) for USACE, portfolio risk assessment for a large UK dam owner (ResRisk), and real-time reservoir flood operation for Reclamation, USACE and SAFCA. David is the Managing Principal of RAC Engineers and Economists and an Emeritus Professor of Civil and Environmental Engineering at Utah State University (USU). Previous positions include Director of the Institute for Dam Safety Risk Management and Director of Utah Center for Water Resources Research at USU, Engineering Department Manager and Branch Manager for Law Engineering’s Denver office, and a construction and design engineer for a large international contractor based in the UK. Home Page (including links to selected papers): http://uwrl.usu.edu/davidsbowles