Transformation of Directional Wave Spreading in the Surf Zone Using Video Image Data

Abstract

In present study, video images technique is used to investigate
the transformation of the directional wave spreading in shallow
water. The technique is based on time series of the pixel
brightness on video images. The Bayesian Directional Method is
conducted in estimating the directional wave spectrum for
evaluating the change of the directional wave spreading in the
surf zone area. Video image data recorded at Hasaki beach in
Japan are used in the analysis. Estimation of principle direction
and spreading parameter in the surf zone regions indicated that
principle directions at peak frequency are not strongly affected by
wave breaking process. In contrast, the broadenings of directional
spreading were observed when the waves start breaking on the
sand bar and toward the shore area.