172
R.H. Charlier and Chr. P. De Meyer
The width of the surf zone (Z) is given by :
Z = BH3/2/[(s-I)I/2D1/21
(12)
where H and D have dimensions similar to those in equation 11, although D
represents in this case the median diameter of sediment in the beach face (near
the SWL).
For the swell-built profile factor B above has the value 43.5, whilst for the stormwave surf zone it is 75.0. In this latter case, a full spectrum of waves is implied,
so that H must be representative of this. Bruun [P. Bruun, 1963. Longshore
currents in one and multibar profiles relating to littoral drift. Proc. 8th Conf.
Coastal Eng., 211-247] has employed H1/3 for such a purpose.
The cross-sectional area of water in the storm beach surf zone is given by Sitarz
(op. cir.) as :
A = (3.4gl/2H21/3T1/3)/[(s-l)l/2D1/2 ]
(13)
where T1/3 is the significant wave period ; g is 9.81 m/sec 2 ; D is the median
sediment diameter across the surf zone ; and Hi/3 and s are defined as before.
Having established the swell profile existing at any time, either completely by
survey, or partly by survey and partly by computation, the width Z and depth d s
of the probable storm profile can be overlain so as to predict the likely beach
degradation. In this respect the slope of the storm beach face, which is very steep,
is of little consequence compared to the other relevant dimensions.
R.H. Charlier and Chr. P. De Meyer
The width of the surf zone (Z) is given by :
Z = BH3/2/[(s-I)I/2D1/21
(12)
where H and D have dimensions similar to those in equation 11, although D
represents in this case the median diameter of sediment in the beach face (near
the SWL).
For the swell-built profile factor B above has the value 43.5, whilst for the stormwave surf zone it is 75.0. In this latter case, a full spectrum of waves is implied,
so that H must be representative of this. Bruun [P. Bruun, 1963. Longshore
currents in one and multibar profiles relating to littoral drift. Proc. 8th Conf.
Coastal Eng., 211-247] has employed H1/3 for such a purpose.
The cross-sectional area of water in the storm beach surf zone is given by Sitarz
(op. cir.) as :
A = (3.4gl/2H21/3T1/3)/[(s-l)l/2D1/2 ]
(13)
where T1/3 is the significant wave period ; g is 9.81 m/sec 2 ; D is the median
sediment diameter across the surf zone ; and Hi/3 and s are defined as before.
Having established the swell profile existing at any time, either completely by
survey, or partly by survey and partly by computation, the width Z and depth d s
of the probable storm profile can be overlain so as to predict the likely beach
degradation. In this respect the slope of the storm beach face, which is very steep,
is of little consequence compared to the other relevant dimensions.