314
R.H. Charlier and Chr. P. De Meyer
2
Littoral Drift
Only transport in the surf zone will be handled under this heading, though it also
takes place offshore. Deep water wave characteristics can be related to wave
energy - and its longshore component-values. Other factors, e.g. energy
dissipation, are difficult to assess.
2.1
The current
R. Sylvester (1989, Ocean Engineering : Amsterdam, Elsevier Science Publ.)
considered it '~lmost impossible ... to correlate a littoral current with waves
breaking on a coast ... oriented almost north-south", in a beach profile example.
Temporal variables involved ought thus to be stressed. He quotes researchers
stating that the near-shore topography redistributes the breaker influx into
different positions along the shore and also undergoes itself displacements and
transformations caused by affected waves and currents. Per Bruun studied the
beach storm profile.
2.2
Drift
It is virtually impossible to mathematically pass from current to drift without
field tests or introduction of empirical values. Setting
m = x beach slope
K' = roughness factor
waver power per shore length unit being P
to = specific weight w~t~r
S = specific gravity s~,t
0 = sediment internal friction angle
p=
2
22t,~H~ sinta b costa b
wHoL 0 sinta b costa o
T
16T
(110
H b
H b
H b
H b
m
L b
CbT ~
T
~/1.78g 13H b T
(112)
R.H. Charlier and Chr. P. De Meyer
2
Littoral Drift
Only transport in the surf zone will be handled under this heading, though it also
takes place offshore. Deep water wave characteristics can be related to wave
energy - and its longshore component-values. Other factors, e.g. energy
dissipation, are difficult to assess.
2.1
The current
R. Sylvester (1989, Ocean Engineering : Amsterdam, Elsevier Science Publ.)
considered it '~lmost impossible ... to correlate a littoral current with waves
breaking on a coast ... oriented almost north-south", in a beach profile example.
Temporal variables involved ought thus to be stressed. He quotes researchers
stating that the near-shore topography redistributes the breaker influx into
different positions along the shore and also undergoes itself displacements and
transformations caused by affected waves and currents. Per Bruun studied the
beach storm profile.
2.2
Drift
It is virtually impossible to mathematically pass from current to drift without
field tests or introduction of empirical values. Setting
m = x beach slope
K' = roughness factor
waver power per shore length unit being P
to = specific weight w~t~r
S = specific gravity s~,t
0 = sediment internal friction angle
p=
2
22t,~H~ sinta b costa b
wHoL 0 sinta b costa o
T
16T
(110
H b
H b
H b
H b
m
L b
CbT ~
T
~/1.78g 13H b T
(112)