Wave Runup
"Experience has shown that embankment dams with large reservoirs and long fetches can be subject to the buildup of very large waves that could run high up on the upstream slope. Dam crests can be damaged and embankment dams can possibly fail by wave action even before they would be subject to flood overtopping. Some small dams have been damaged as well. Splash and spray over a dam crest is not uncommon when high velocity winds occur over high reservoir water surfaces. Hurricanes can produce this damaging combination because high velocity winds can persist through the peak reservoir levels. Wind and wave action have long been considered significant factors in the determination of the design crest elevation (not including camber) of an embankment dam and the analysis of all types of freeboard."[1]
"Wind-generated wave heights and wave runup are probably the most thoroughly studied and understood factors that influence freeboard. Much of the study has been carried out and reported by the U.S. Army Corps of Engineers. Wave generation is influenced by wind characteristics such as velocity, duration, and orientation with respect to the reservoir; by topographic configuration of the reservoir, including depth and shoaling effects; and by fetch. Fetch accounts for the effects of the length of the open-water approach of the waves. Wave runup is governed by the height and steepness of the waves; by the slope, roughness, and porosity of the dam face; by changes in the slope of the dam face; and by the presence of berms on the dam face. Setup is caused by the shearing effect of the wind that tends to tilt the reservoir higher in the direction of the wind."[1]
Best Practices Resources
Design Standards No. 13: Embankment Dams (Ch. 6: Freeboard), USBR
Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420), USACE
Trainings
On-Demand Webinar: Designing Slope Protection for Dams and Levees
Citations:
Revision ID: 7354
Revision Date: 07/21/2023