2007 – Incremental consequences of dam failure and the ANCOLD hazard classification system

Peter Hill, Leonard McDonald and Emily Payne

The concept of incremental consequences of failure is embedded in the both the relevant ANCOLD and NZSOLD guidelines on risk and dam safety. This paper addresses two issues with respect to how these incremental consequences are estimated and interpreted for dam safety risk applications. The first of these is the estimation of incremental loss of life required as input to risk analyses. This paper provides a review of available empirical techniques and information from flood history databases for estimating the loss of life for non-dambreak floods. The second issue covered is the definition of the Population at Risk for assigning the Hazard (or Consequence) Category of the dam. There are currently different interpretations in industry regarding whether this should be defined on the basis of total or incremental population at risk.