Tailwater Modeling
Elevated tailwater levels can hinder operation or decrease the capacity of lake drain appurtenances and hydroelectric facilities. Localized increases in tailwater could also impact the functionality of certain types of spillways (e.g., fuse plugs, fusegates, or flashboards) or cause submergence of uncontrolled spillways. This may result in decreased spillway capacity and increased risk of overtopping. On the other hand, lower than anticipated tailwater levels can reduce the effectiveness of stilling basins or other energy dissipaters, thereby increasing the risk of scour and erosion downstream of these facilities.
Hydraulic analyses extending downstream of a dam can be completed for a range of anticipated discharges. Output from these analyses can be used to develop a tailwater rating curve for a given structure and understand potential impacts to dam appurtenances during flood events.
It is important to consider how tailwater conditions may change over time due to natural or man-made conditions downstream of the immediate vicinity of the dam. For example, the construction of new road embankments or culvert replacements, the building of beaver dams and other natural obstructions, the failure of sizeable roadway embankments during a flood, or the buildup of sediment in downstream channels due to erosion problems at the dam may result in significant and even sudden changes in tailwater conditions.
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Revision ID: 5493
Revision Date: 12/13/2022