Spillway systems reliability
Desmond ND Hartford,
Gregory B Baecher,
P Andy Zielinski,
Robert C Patev,
Dam owners must prioritise spillway system repair and upgrading in view of the large costs involved. Some analytical means is needed through which the most critical dams and system components in a portfolio can be identified, and cost-effective plans can be developed for their remediation. For the most part, however, such analytical tools are not available. This situation is unsurprising even given the maturity of water resource engineering. Other safety-driven industries such as chemical processing, aerospace engineering, and even other sectors of electrical power generation, face a similar situation: traditional engineering analysis tools have evolved in response to design needs, not operational needs. Traditional engineering analysis tools focus on the capacity necessary to meet specified demands and on compliance with codes or regulations. They mostly ignore operational and systems effects, including the interplay of human operators, modern sensor and control systems, and randomness.
The approach to the analysis and understanding of operational safety of dams and reservoirs developed in this project starts from the observation that the dominant risks to be managed in dam safety derive not from unique events but from adverse combinations of more usual events. One might think of these as unusual combinations of usual conditions. The timing of such events and their magnitudes can create conditions to which the dam had not been designed and which were not accounted for in preparing operational plans and strategies. These include the systems interactions among management policy, procedural factors, instrumentation and SCADA systems, operational and maintenance practices, design flaws, construction compromises, deterioration, outside disturbances, and many other things that are often overlooked at the time of design. The result is that many systems failures do not fit within a traditional engineering-analytic framework and a new systems framework is needed.
Baecher, Gregory B.
An in-depth assessment of the adequacy of the 1-percent annual chance flood standard as a key component of the National Flood Insurance Program (NFIP) and an examination of the impacts of possible changes to this standard or the establishment of a new standard. In carrying out this task the team is fully examining the scientific, social and political aspects of the establishment of floodplain regulatory standards in general and the 1-percent standard in particular, how such standards influence behavior and as a result, the costs to the nation of flooding, and what benefits or costs, if any, might accrue from changes in the standard.
The evaluation is both quantitative and qualitative and draws from a wide range of sources. Our team intends to cast a wide net to draw from the knowledge of individuals, organizations, and databases throughout the nation and, in some cases, from experiences abroad. Based on the collective experience of team members and from interviews conducted during the research, it is clear that data do not exist that provide incontrovertible evidence of the efficacy of or the absolute deficiency in use of a 1-percent standard. However, careful analysis of a wide variety of data, some national, some local, and data developed through models such as HAZUS, the loss risk estimator developed by FEMA, the project has been able to develop defensible responses to the quantitative and qualitative evaluation questions posed.