52
Coastal Engineering: Theory and Practice
where, D50 is the médian grain size in mm and Hb is the breaking wave
height in m.
Zone 3:
Based on the assumptions of Kriebel and Dean [1985] that the crossshore transport rate is proportional to the excess energy dissipation per unit
volume over a certain equilibrium value of energy dissipation (Deq) in fully
broken waves, which was defined by the amount of energy dissipation per
unit volume that a beach with a spécifie grain size could withstand without
generating significant sédiment transport. In other words, the cross-shore
transport rate “g” in fully broken wave région with horizontal sea floor, is
expressed as,
q = K(D - D.,)
(3.19a)
D = (l/h)(dF/ic)
(3.19b)
(3.19c)
h — d + r/
(3.19d)
d: water depth (m) from the undisturbed free surface, r): set up/set down
(m), A is the Brunn’s shape parameter, mainly a function of D$q and K:
transport coefficient (m4/N).
As the transport rate also dépends on the local slope of the sea floor, an
extra term is added to account for the effect of the local slope. With this
modification the transport rate becomes,
q = K[D- Deq + (e/Æ)(dd/dx)], D > Deq - ^/K^dd/dx) = 0,
D < Deq - (e/K^dd/dx')
(3.20)
where e is the slope related transport rate coefficient (m2/sec).
Zone J:
The transport rate in the swash zone is assumed to decrease linearly
from the end of the surf zone (Zone 3) to the run-up limit given by,
q = qz{(x - xr)/(æ2 - ær)}
(3.21)
where subscripts “z” and “r” are for quantities evaluated at the end of
the surf zone and run-up limit, respectively. The active sub-aerial profile
height zr or z-coordinate of the run-up limit of waves is determined using
Coastal Engineering: Theory and Practice
where, D50 is the médian grain size in mm and Hb is the breaking wave
height in m.
Zone 3:
Based on the assumptions of Kriebel and Dean [1985] that the crossshore transport rate is proportional to the excess energy dissipation per unit
volume over a certain equilibrium value of energy dissipation (Deq) in fully
broken waves, which was defined by the amount of energy dissipation per
unit volume that a beach with a spécifie grain size could withstand without
generating significant sédiment transport. In other words, the cross-shore
transport rate “g” in fully broken wave région with horizontal sea floor, is
expressed as,
q = K(D - D.,)
(3.19a)
D = (l/h)(dF/ic)
(3.19b)
(3.19c)
h — d + r/
(3.19d)
d: water depth (m) from the undisturbed free surface, r): set up/set down
(m), A is the Brunn’s shape parameter, mainly a function of D$q and K:
transport coefficient (m4/N).
As the transport rate also dépends on the local slope of the sea floor, an
extra term is added to account for the effect of the local slope. With this
modification the transport rate becomes,
q = K[D- Deq + (e/Æ)(dd/dx)], D > Deq - ^/K^dd/dx) = 0,
D < Deq - (e/K^dd/dx')
(3.20)
where e is the slope related transport rate coefficient (m2/sec).
Zone J:
The transport rate in the swash zone is assumed to decrease linearly
from the end of the surf zone (Zone 3) to the run-up limit given by,
q = qz{(x - xr)/(æ2 - ær)}
(3.21)
where subscripts “z” and “r” are for quantities evaluated at the end of
the surf zone and run-up limit, respectively. The active sub-aerial profile
height zr or z-coordinate of the run-up limit of waves is determined using