6.
CONCLUSIONS
This study shows that transformation of the WIS hindcast spectra using STWAVE provides improved results over
driving STWAVE using parametric spectra based on the bulk parameters of wave height, peak period, and mean
direction. Error statistics show marginal improvement in the modeled nearshore wave height, but significant
improvement in peak period and mean direction. The wave energy and direction are the key parameters for
estimating longshore energy flux and longshore sediment transport. These improvements come at the cost of
increased computation effort. Longshore transport is driven by large wave events, so errors in the STWAVE input
conditions for a single large wave event, such as Hurricane Bonnie in August of 1998, can dominate the estimate of
cumulative transport over a full year. Thus, good understanding of the error characteristics of the WIS hindcast is
critical for application of the data to drive nearshore wave transformation. Use of hindcast (or measured) frequency-
direction spectral to drive nearshore transformation preserves the complexity of the wave field (frequency and
directional distributions, including multiple wave trains) and improves estimates of potential longshore sediment
transport.
7.
ACKNOWLEDGEMENTS
Permission to publish this paper was granted by the Office, Chief of Engineers, U.S. Army Corps of Engineers.
This research was conducted under the Transformation-Scale Waves work unit in the Coastal Navigation Program of
the Coastal and Hydraulics Laboratory, U.S. Army Engineer Research and Development Center. Barbara Tracy and
Jane Payne of the Wave Information Studies supplied WIS results, and Ann Sherlock assisted with model runs.
Field data were collected and analyzed by Chuck Long at the Field Research Facility, Coastal and Hydraulics
Laboratory, U.S. Army Engineer Research and Development Center.
8.
REFERENCES
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