(a) Horizontal currents can modify surface gravity waves by stretching or shrinking features of a wave

train. This distortion can produce a "Doppler Shift" in wave period. Wave orthogonal, crest, and ray

directions are modified (see Part II-1 for definitions). Also, a current modifies surface waves by causing an

exchange of energy between wave and current. The pressure field accompanying the wave also is modified.

Predicting current-modified wave energy, heights, directions, and pressures is typically a complex procedure

still under research; however, a graphical method presented by Herchenroder (1981) based on work by

Jonsson et al. (1970), can be used to estimate the effect of current on wave height *H*A, where this is wave

height without current.

Using the equation:

(II-6-29)

(b) Figure II-6-34 may be used to determine *R*H, the wave height factor, which depends on:

II-6-40

Hydrodynamics of Tidal Inlets

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