Decision analysis in dam safety monitoring

The storages of many low head power plants in Romania are provided by long earthfill lateral darns. In most of the cases they are homogeneous dams with upstream concrete face and downstream drainage. Being located in piedmont plains the surrounding zones of reservoirs are densely populated and full economically developed. In the case of it dam failure the uncontrolled loss of reservoir content can have a disastrous impact leading to life loss, injuries, direct economic losses, interruption of benefits from the clam, etc. The economic consequences can be assesses and the annual risk carl be defined multiplying the failure probability per year with the monetary value of the consequences. The expected monetary loss can be reduced if the probability of failure can be controlled by dam monitoring. For very long earthfill dams the effectiveness of the dam monitoring asks for regularly and qualified inspections, the increase of piezometric profiles, the performing of thermographic measurements, etc., which carl be expensive. The actual decision involves a basic trade-off between the reduction of the expected monetary loss and the cost for providing added protection. The decision is based oil maximizing the net expected benefit. In the first part the paper presents the procedure for defining the strategies in dam monitoring improvement based on the net expected benefit. In the second part the actual application of this procedure to Strejesti hydropower development is treated in details emphasizing the importance of the decision strategies in the case of a limited annual budget.