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Using risk to inform overtopping protection decisions




Fiedler, W. R., author
Colorado State University. Department of Engineering, publisher

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The decision to implement overtopping protection as a dam safety modification alternative can be difficult. The decision involves a conscious decision to allow a dam to overtop for floods above a threshold flood. If a large flood occurs that initiates dam overtopping, there is no turning back, and the dam and the overtopping protection must be able to resist the overtopping flows. The chance of intervention being successful for a dam that is already overtopping, should erosion initiate, would be very unlikely. There is more of a comfort level among many dam engineers in providing conventional solutions to a dam overtopping issue. These traditional measures include raising the dam crest to provide additional surcharge space to store a portion of the flood inflows or providing additional spillway capacity to more closely match the peak flood inflows. There is often the perception among experienced dam engineers that these traditional measures provide a safer solution and pose less risk than an overtopping solution. This paper will present scenarios that demonstrate that in some cases, overtopping protection may be just as safe or the safer alternative, by exposing the downstream population to equal or less risk of dam failure during a large flood event. These scenarios will consist of an embankment dam where a replacement gated spillway alternative will be compared to overtopping protection and a concrete dam where raising of the dam will be compared to providing overtopping protection for the dam foundation.


Presented at the Protections 2016: 2nd international seminar on dam protection against overtopping: concrete dams, embankment dams, levees, tailings dams held on 7th-9th September, 2016, at Colorado State University in Fort Collins, Colorado, USA. The increasing demand for dam and levee safety and flood protection has motivated new research and advancements and a greater need for cost-effective measures in overtopping protection as a solution for overtopping concerns at levees and dams. This seminar will bring together leading experts from practice, research, development, and implementation for two days of knowledge exchange followed by a technical tour of the Colorado State University Hydraulic Laboratory with overtopping flume and wave simulator. This seminar will focus on: Critical issues related to levees and dams; New developments and advanced tools; Overtopping protection systems; System design and performance; Applications and innovative solutions; Case histories of overtopping events; Physical modeling techniques and recent studies; and Numerical modeling methods.
Includes bibliographical references.

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overtopping protection
dam safety


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