Shoaling of Wave Spectra in Front of Reflective Structures

Smith, Ernest R.; Hughes, Steven A.; ,

Shoaling of Wave Spectra in Front of Reflective Structures

by Ernest R. Smith, U.S. Army Engineer Waterways, Experiment Station, Vicksburg, United States,
Steven A. Hughes, U.S. Army Engineer Waterways, Experiment Station, Vicksburg, United States,

Document Type: Proceeding Paper

Part of: Ocean Wave Measurement and Analysis

Abstract:

Breakwater and jetty design depend in part on the incident significant wave height expected to reach the structure. This height is not always known and must be estimated from a deepwater condition obtained from either gage measurements or wave hindcasts. Numerical models have been developed to transform the wave condition from deep water to the shallow water depth. These models typically are calibrated and verified using laboratory and/or field studies with plane slopes or irregular profiles from which wave reflection is small. However, it is not known how well these wave transformation techniques predict the incident wave spectrum in the presence of significant wave reflection. This paper presents results of wave transformation laboratory experiments conducted on a plane slope fronting a reflective structure. Incident and reflected significant wave heights were measured at various depths seaward of the structure using the co-located velocity method described by Hughes (1993). Transformation of the measured incident wave height was compared to estimates made using linear transformation (Airy 1845) and random wave transformation (Goda 1975). For the random wave conditions tested, both transformations method provided estimates that compared well with estimates based on measurements made at each location. The inverse shoaling of the reflected wave was also compared to predictions of the linear theory and Goda random wave transformation with less favorable results.

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