Portfolio Risk Assessment: A Basis for Prioritizing and Coordinating Dam Safety Activities

A Portfolio Risk Assessment (PRA) of a group of existing dams is based primarily on available information, without performing extensive additional analyses or investigations. A PRA provides a baseline assessment of a group of existing dams and an initial prioritization of future dam safety investigations and remedial works. The basis for this prioritization is maximizing the rate of risk reduction, but other factors that are important to the regulatory program or to the owner's business can be included. As a baseline assessment, the PRA should become a "living document" that is updated using additional information as it becomes available, thus providing a firm basis for decisions on remedial works and coordination of all aspects of dam safety risk management, including the following: monitoring and surveillance, operations and maintenance; staff training and awareness of potential failure modes; and emergency warning systems.
This paper summarizes the PRA process and the role that it can play in a dam safety regulatory program or the dam safety program of a private or governmental dam owner. Results are displayed for individual dams and the entire portfolio. The safety of each dam is compared with both engineering standards and dam safety tolerable risk criteria. Various options are provided for ranking risk reduction measures across the portfolio and for displaying portfolio risk reduction against time or expenditure. The information provided has proven to be valuable for regulators and dam owners in developing their dam safety management programs and for capital budgeting, due diligence considerations and evaluation of loss financing and insurance programs. Examples of PRA outputs will be based on several PRAs completed by the authors and will include a discussion of the use to which these outputs are being put by regulators and owners. Comparisons will be made with traditional approaches to prioritizing dam safety programs. 14 pp., 15 references.