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|Title:||Model study of overtopping of wind-generated waves on levees with slopes of 1:3 and 1:6|
|Authors:||United States. Army. Corps of Engineers. Jacksonville District|
University of California, Berkeley, Wave Research Laboratory
United States. Army. Office of the Chief of Engineers
Sibul, Osvald J.
Tickner, Ernest Glenn
Wind-wave tunnel experiments
|Publisher:||United States, Beach Erosion Board|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical memorandum (United States. Beach Erosion Board) ; no. 80.|
Abstract: The overtopping of waves on levees with slopes of 1:3 and 1:6 was studied in a laboratory wind-wave tunnel. The results were compared with experiments conducted at the Waterways Experiment Station, Vicksburg, Mississippi, where the tests were were accomplished with mechanically-generated uniform waves which were not affected by wind. For low-wind velocities the results of the present tests are similar to the Vicksburg tests. For higher wind velocities, however, an additional overtopping occurs due to the wind action, so that the total overtopping could be separated into two parts; that is, 1. Overtopping due to the wave action (based on the WES experiments) 2. Overtopping due to the wind action (based on wind-wave tunnel experiments) The laboratory tests showed that the wind starts to affect the results for wind speeds above 10 mph for the 1:6 slope levee and above 20 mph for the 1:3 slope levee. It is expected that for the prototype this critical wind speed probably would be considerably higher. Froude's similarity law is probably not applicable in predicting critical prototype wind speeds. For example, the critical speed at the given linear scale ration 1:67.5 is 80 mph for the 1:6 slope levee and 160 mph for the 1:3 slope levee. The additional overtopping due to the wind depends on the slope of the levee, and the slope remains the same regardless of the scale-ratio. The volume of overtopping, however, depends upon the intensity of the wind, and requires a higher wind shear stress to achieve the rate of flow for the prototype which would be predicted from the model discharge. The direct effect of wind on the overtopping of waves should therefore be regarded as qualitative and give only the trend for overtopping effects when the wind speed is increased.
|Appears in Collections:||Technical Memorandum|