Use of risk assessment for dam safety evaluation in Australia

This paper outlines the role of risk assessment in dam safety evaluation to the present time. The traditional standards-based approach to safety evaluation, as practised in Australia, is briefly described. The history of development of probabilistic approaches in this country is given, with particular discussion of the Australian National Committee on Large Dams (ANCOLD) Guidelines on Risk Assessment, published in 1994. The life safety acceptance criteria of those guidelines, and the planned modifications to these for updated guidelines, now in preparation, are given special emphasis. Examples of applications of risk assessment are given, with particular attention to the increasing use of the portfolio risk assessment concept. The methodologies used for detailed risk assessments, and the difficulties with some of these, are outlined. The substantial benefits of risk assessment to dam safety programs are described, together with the problems that have been encountered in applying risk concepts. Areas requiring further research and development are outlined. Finally, the author's current perspective, on the role of risk assessment in the overall framework of dam safety programs, is given.