—_—ss— creasing Time 
a Contour 
Z 
J 
Z, 
Z 
y 
uy 
Yo 3 
Z 
ts 
Z 
YZ, 
GZ 
Z 
y 
Y 
Z 
Z 
Y 
Y 
Z 
“ 
Zone of Oversteepened Profiles 
“ty / 
a 
Zone of 
F =/-— Flattened 
Profiles 
{ 
(a) Offshore Transport on Over- (b) Onshore Transport on Flattened Ic) Onshore Trai i 
steepaned Profiles and Long- Profiles and Longshore Transport a Flattened Pemee Di is eee 
shore Transport Due to Wave Due to Wave Obiiquity. shore Transport Distribution 
Qbliauity Across the Surf Zone. 
Figure 25. Three phases of observed sediment transport in vicinity of 
nourished projects (Note: cross-contour transport because of profile 
disequilibrium (from Dean et al. 1993)) 
6M Gay () 
in which ¢ represents time and x and y are the longshore and cross-shore 
distances from the origin, respectively. The parameter G is called the alongshore 
diffusivity and is expressed as follows (in terms of breaking wave conditions) 
Kh, {glx 
G = ————_———— (for breaking conditions) (2) 
8(s-1)(1 -p)(h,+ B) 
where 
K = asediment transport factor usually taken as 0.77 
h, = breaking wave height 
g = acceleration of gravity 
= ratio of breaking wave height to local water depth (usually taken as 
0.78) 
Chapter 4 Beach-Fill End Losses 
Sil 
