Kent K. Hathaway

Michael W. Leffler

William Allen Birkemeier

Clifford F. Baron

H. Carl Miller

John B. Strider

During September and October 1986, the US Army Engineer Waterways Experiment Station's Coastal Engineering Research Center (CERC) hosted SUPERDUCK, a nearshore processes experiment, at its Field Research Facility located at Duck, North Carolina. The objectives of SUPERDUCK were to develop an improved understanding of coastal processes (currents, waves, sediment transport, and nearshore geomorphology) under a wide variety of conditions and to collect data essential to the development of improved numerical models of coastal phenomena. Critical to the success of SUPERDUCK was the collection of a basic suite of bathymetric surveys and instrument measurements by CERC's Field Research Facility. The measurements included nearshore current, tide, incident directional wave, and meteorological data. In addition, a series of 14 surveys of the bathymetry in the experiment area was collected. (RRH).

CERC Field Research Facility

SUPERDUCK Nearshore Processes Experiment Data Summary

This report summarizes the present state of knowledge on infragravity wave motions (nominally 0.003 to 0.05 Hz). Theoretical and observational studies are presented. Most of the studies discussed herein have been published elsewhere, however a few studies discussed in chapter 4 are presented for the first time in this report Measurements of nearshore waves and currents have shown that a significant amount of the total energy can be contained in the infragravity band, and on highly dissipative beaches the infragravity wave variance often dominates over energy in the incident wave band(0.05 to 0.3 Hz). An 8-month data set of infragravity variance measured at 8-m-depth at the shoreline (runup) was compared with incident wave variance. Analysis of the 8-m-depth data showed that high mode edge waves account for about 50 percent of the total infragravity variance, and as high as 80 percent at times. Significant edge wave heights greater than 20 cm were observed at the 8-m depth. Infragravity wave variance was shown to have a higher correlation with swell variance (C = 0.95) than with sea variance (C = 0.61). This report was motivated, in part, by the need to determine the significance of infragravity waves on coastal erosion and structure damage and by the desire to improve coastal engineering solutions to problems associated with nearshore processes.

Kent K. Hathaway

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