Hmay be expressed as
HKsKrH 0 (14.34)
whereKs(Cg0/Cg)1/2is the shoaling coefficient. To facilitate drawing of
refraction patterns, use can be made of Fig. 14.8, which shows graphically
the various wave properties locally at depth d, expressed in relation to the
deep-water conditions.
As the bed topography can be highly irregular, the numerical
approach to the refraction diagram involves a step-by-step determination
of the advancement of the wave crests. The local celerity and wavelength
are taken to be those of small-amplitude, long-crested waves over uniform
depth equal to the local depth. A method of tracing rays from deep water
is illustrated in a worked example at the end of this chapter.
14.5 Wave breaking
Miche’s criterion for breaking of regular waves at constant depth is
H/L0.142 tanh(5.5d/L) (14.35)
Waves in deep water break when their steepness H 0 /L 0 exceeds 1/7
(equation (14.27)). In shallow water, the wave profile approximates that of
a solitary wave before breaking. A solitary wave breaks when
588 WAVES AND OFFSHORE ENGINEERING
Fig. 14.8 The shore transforms for an Airy wave
