Hydrologic Issues for Dams - Association of State Dam Safety Officials

CURRENT AND FUTURE HYDROLOGIC RESEARCH NEEDS FORDAM SAFETY ANALYSIS IN MATURE DAM SAFETY PROGRAMSByD.N.D. Hartford 1Considerations for Dam OwnersDam owners have a duty of care to protect the public, property and the environment fromharm that might result from their operations. In this regard, the dam owner can beconsidered to be the creator of the risk and increasingly there are requirements in law forthe dam owner to identify the hazards, assess the risks, prepare a safety casedemonstrating how the risks will be prevented or otherwise controlled, and set out asafety management system showing how the safety case will be implemented andmaintained.Risk assessment, which provides a structured, systematic examination of the likelihood ofharmful events and the associated consequences should the events occur, is the essentialanticipatory element that underpins the safety case. Therefore, in the preparation of thesafety case and in demonstrating due diligence in risk management and control thequality of the risk assessment is of paramount importance to the owner. Therefore,research into the quality of the risk assessment process is of obvious interest to damowners.A second very important consideration pertains to the context within which a dam safetydecision is to be made. The modern view from the perspective of a risk regulator (HSE,2001) is that ”the proper use of risk assessment would require inter alia that:• more often than not, the results of a risk assessment should be expressed as a valuejudgement rather than a number;• the risk problem should be properly framed• the nature and limitations of the risk assessment are understood; and• the results of the risk assessment are used to inform rather than to dictate decisionsand are only one of the many factors taken into account in reaching a decision.”Researching what all of this means and its implications are a second interest to damowners.The dam owners risk profile, characterized in large part by the consequences of damfailures for the portfolio, provides a third important consideration which must beaccounted for in the risk assessment and decision-making processes. Societalcatastrophic loss risk management is different to the other risks managed by dam owners.The rules for decision-making for catastrophic loss risks are also different, as are therepresentations of the risk. The decision and risk assessment processes used by an ownerwhose losses are limited or insurable can be expected to be different to those ownersmanaging catastrophic loss risks.1 BC Hydro85Paper 14 - Hartford