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|Title:||Laboratory effects in beach studies, volume 6: movable-bed experiments with Ho/Lo = 0.004|
|Authors:||Chesnutt, Charles B.|
Stafford, Robert P.
Wave Height Variability
|Publisher:||Coastal Engineering Research Center (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous report (Coastal Engineering Research Center (U.S.)) ; no. 77-7 v. 6.|
Abstract: Two experiments with long low waves on 0.2-millimeter sand slopes in tanks 6 and 10 feet wide showed very different profile development, apparently because current circulation, present only in the 6-foot tank, was more effective in distributing sand in the onshore-offshore direction. In the 6-foot tank, the profile developed a more distinct shelf separated by two relatively steep seaward-facing slopes. The clockwise circulation pattern occurred over the shelf between the foreshore and the first seaward anti node of the standing wave envelope, a distance approximately twice the tank width. This current pattern in the 6-foot tank began to disintegrate after about 70 hours. The profile in the 6-foot tank was still changing at 135 hours when the experiment ended; in the 10-foot tank, the profile had reached approximate equilibrium after 25 hours. In the 6-foot tank, the foreshore eroded throughout the test, but in the 10-foot tank it quickly stabilized. In the 6-foot tank, the offshore consisted of an almost flat shelf and a steep seaward slope as long as the circulation prevailed, but became more gently sloping after the circulation disappeared. In the 10-foot tank, the offshore was less steep and stabilized after about 50 hours. Reflection coefficient, KR varied from 0.17 to 0.31 in the 6-foot tank, increaslng as the shelf developed during the time of active circulation. KR then began decreasing as the steep offshore slope began flattening. In the 10-foot tank, KR was higher, varying from 0.24 to 0.37 and tended to increase with steepening of the foreshore. Note: Reflection coefficient KR is not accurately represented in this online abstract due to the character set limitations of this system. The coefficient will be accurately presented in the downloaded pdf.
|Appears in Collections:||Miscellaneous Report|