144
.................. R:I-I. Charlier and Chr. P. De Meyer
The term D + BH is, of course, the total depth over which the beach profile
changes.
~ ~Crt Z
S~w~ ~tl tw, e
'////j/fT/.,'..-.,
/ /////////////
Bose t,'n e
* X
Fig. 33 : Breaker angle
Ozasa and Brampton (1980) used a new formula for the alongshore transport of
sediment. In normal situations, alongshore transport on beaches is caused by the
oblique breaking of waves. In some case, however, alongshore wave height
gradients must also be considered. Such situations often occur when waves
diffract around a headland or a breakwater. The equation for the volume rate of
alongshore sediment transport used by Ozasa and Brampton takes both these
effects into account and is given by :
I
)
Q -
sinot b - %24
cot,//cosa b
(100)
y~
c3x
where :
E
=
H
=
g
=
C~ =
p
=
1 re'n ~
the energy density of the waves = -
8
the wave height,
the acceleration due to gravity,
the group velocity of the waves,
the angle their crests make with the shoreline,
the density of the water,