62
Coastal Engineering: Theory and Practice
The value 2.33 is a dimensional coefficient related to the SI System
assuming sait water (1030 kg/m3). The prédictions through the formula of
Kamphuis [1991] were consistent for both spilling and plunger breakers over
CERC method of sédiment transport estimation.
3.8.7 Sédiment distribution across the surf zone
Wave-induced longshore currents at the mid surf-position hâve been evaluated nsing the relation suggested by Komar [1975] according to which,
V = 2.7 um sin ab cos &b
(3.35)
where u™ = 12? C. is the maximum horizontal velocity of the waves,
- is the wave breaking index, a constant whose value is 0.78. C is the wave
z+tesirry in shahow water.
is the breaker angle.
It shouSi be noted that the above équation is independent of the
teach. slope. though the longshore carrent velocity formula reeommended
y CERC [1984. based on Longuet-Higgins 1970] is dépendent on beach
slope. However. Komar 1979. has tested the dependence of longshore carrent and stated it is not directly proportional to the beach slope as stated
in the CERC formula.
This method has some more basis than other two method, that the
longshore carrent is computed [Longaet-Higgins, 1970] by eqaating gradient
in the radiation shear stress to bottom friction, with assamption that, the
shallow-water wave theory is valid only till the breaker line where the depth
d is equal to hb, the mean longshore entrent, in the absence of horizontal
mixing. In the présent study the coast has been assumed to be without
groins for computing sédiment transport using this method.
(
5tt ' X ( 1 \
77 ) ( 7=7 ) (p^b)0'5
• sin ctb
(3.36)
luj yOf j
where, m
the bed slope; Cf — current friction factor (around 0.01;
Longuet-Higgins, 1970); y — H/d and e = 1/(1 + 0.375y2).
However in the real sea conditions, the propagating wave will be of
random in nature and hence, there will be a latéral mixing due to different va\es with varying period breaks consecutively. Hence, he proposed a
solution as
TZ ^X^+AX for0
(3.37)
[B2XP2
for 1 < X < oo
w here X and V are in non-dimensional form.
Coastal Engineering: Theory and Practice
The value 2.33 is a dimensional coefficient related to the SI System
assuming sait water (1030 kg/m3). The prédictions through the formula of
Kamphuis [1991] were consistent for both spilling and plunger breakers over
CERC method of sédiment transport estimation.
3.8.7 Sédiment distribution across the surf zone
Wave-induced longshore currents at the mid surf-position hâve been evaluated nsing the relation suggested by Komar [1975] according to which,
V = 2.7 um sin ab cos &b
(3.35)
where u™ = 12? C. is the maximum horizontal velocity of the waves,
- is the wave breaking index, a constant whose value is 0.78. C is the wave
z+tesirry in shahow water.
is the breaker angle.
It shouSi be noted that the above équation is independent of the
teach. slope. though the longshore carrent velocity formula reeommended
y CERC [1984. based on Longuet-Higgins 1970] is dépendent on beach
slope. However. Komar 1979. has tested the dependence of longshore carrent and stated it is not directly proportional to the beach slope as stated
in the CERC formula.
This method has some more basis than other two method, that the
longshore carrent is computed [Longaet-Higgins, 1970] by eqaating gradient
in the radiation shear stress to bottom friction, with assamption that, the
shallow-water wave theory is valid only till the breaker line where the depth
d is equal to hb, the mean longshore entrent, in the absence of horizontal
mixing. In the présent study the coast has been assumed to be without
groins for computing sédiment transport using this method.
(
5tt ' X ( 1 \
77 ) ( 7=7 ) (p^b)0'5
• sin ctb
(3.36)
luj yOf j
where, m
the bed slope; Cf — current friction factor (around 0.01;
Longuet-Higgins, 1970); y — H/d and e = 1/(1 + 0.375y2).
However in the real sea conditions, the propagating wave will be of
random in nature and hence, there will be a latéral mixing due to different va\es with varying period breaks consecutively. Hence, he proposed a
solution as
TZ ^X^+AX for0
(3.37)
[B2XP2
for 1 < X < oo
w here X and V are in non-dimensional form.