Risk assessment provides an opportunity to manage dam safety using a framework of risk evaluation that is used for other types of hazardous facilities and technologies. This paper contains a presentation of risk evaluation from a broad perspective but with application to dam safety. The distinction between tolerable and acceptable risk and the difference between risk evaluation under Common Law and Napoleonic Civil Code legal systems is addressed. The common division of risk into individual and societal concerns for the purpose of tolerable risk evaluation is introduced with reference to the topic of perceived risk. Some fundamental principles upon which all individual and societal tolerable risk criteria are based are presented. The generalized framework for the tolerability of risk developed by the UK Health and Safety Executive (HSE) is summarized. The important role of the “aslowasreasonablypracticable” (ALARP) principle in risk evaluation is discussed, including aspects such as cost effectiveness, disproportionality, legal liability, optioneering and uncertainty. Examples of tolerable risk guidelines in use for dam safety in the UK, Australia and the US are presented.

Author names: 
Bowles, D. S.

Bowles, D. S. (2007). Tolerable risk for dams: How safe is safe enough. Proceedings of the 2007 USSD Annual Lecture, Philadelphia, Pennsylvania.

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Climate risks considered: