The tolerable risk level that affects the decision-making process
mostly depends on the societal, financial, and economic consequences
(Nielsen et al. 1994). For this reason, different U.S.-based
or international risk rating systems have been used. These risk rating
systems enable engineers to prioritize the risk levels and take an
action according to them. Examples of commonly known rating
systems include the Dam Safety Priority Rating System (DSPR),
Dam Safety Action Classification (DSAC), the Australian National
Committee on Large Dams (ANCOLD), Canadian Dam Association
(CDA), New South Wales Dam Safety Committee (NSW
DSC), and U.K. Health and Safety Executive (HSE) ratings. There
are differences among these rating systems regarding their acceptable
limits for dam risk measurements, whether they apply the
ALARP criteria, and what types of probability charts they refer
to in the risk rating process. The charts include differences in terms
of whether they represent annualized failure probability versus
number of life losses (i.e., f-N charts) or probability per year for
the potential loss of life versus the number of life losses (i.e., F-N
charts) (Munger 2009).