The dam risk assessment process involves determining the likelihood
of a dominant failure mode or modes (e.g., overtopping, internal
erosion) and then evaluating the consequences of a failure
(e.g., loss of life). Risk is assessed based on a combination of
the likelihood of a failure and the consequences of that failure.
If a dam is determined to be above the tolerable risk, then there
will be justification for remedial action or for more detailed risk
analysis (USACE 2010). The dam risk assessment process is critical
since the societal and economic impacts of failures are too large
to ignore. Especially in the cases of dams in the U.S., the risk assessment
process becomes even more pronounced, as the average
age of dams is around 51 years and a large number of dams have
poor condition ratings (ASCE 2013). Managing aging infrastructure
is a challenge in the U.S. due to budgetary constraints, and
it is not possible to renew or have all remedial actions in place
for all infrastructure systems at the same time. According to the
Association of State Dam Safety Officials, more than $30 billion
is necessary to overcome the problem of the aging of the dams in
the U.S. (Lane 2008). Given the current dam conditions and budgetary
constraints, the risk assessment process becomes much more
prominent.