Uncertainty analysis in Dam safety assessment using ‘weights'and ‘probability’

Dam safety assessment remains the one of the topmost concerns for Dam owners, engineers and regulators who are responsible for the safety of dams and they have to consistently explore the associated risk mitigation measures. There are several tools being employed for this purpose including the most common one of the assessment of risks to downstream areas. These tools help to improve the understanding and management of the risks associated with operating and maintaining dams with the ultimate objectives to improving safety of the public at large and mitigating other appurtenant environmental and social risks.

‘Dam safety risk management’, consisting of dam break analysis, geotechnical and seismic analysis, hydrological studies and uncertainty analysis is specific to each project since it largely depends on its site-specific natural and technical conditions. Almost every dam owner in the world is practicing ‘Dam safety risk management’ of varying magnitude. The Dam owners need is to improve the prevailing practices at different projects and integrate best practices into a set of comprehensive approach of ‘Uncertainty Analysis’ for the benefit of the entire fraternity. Uncertainty analysis such as dam performance, spillway gate reliability, risk evaluation, crisis management and dam failure hazard estimation, use ‘Weight’ and ‘Probability’ inputs. The analysis helps in making an assessment of risks taking into account the inputs like dam behavior under the defined conditions, preparedness to deal with the several crises including the impact on downstream population etc.

The authors of this paper have attempted to transform an effective and efficient program for managing dam safety risks at Tehri Dam Project into a simple model of ‘Uncertainty Analysis’ of ‘Weights’ and ‘Probability’. Application of this model is feasible to the project of almost any magnitude.