A. Bayram et al. / Coastal Engineering 44 (2001) 7999

95

measurements pertaining to longshore sediment trans-

median particle diameter, V the mean longshore cur-

port. Thus, additional calibration of the formulas

rent velocity, C the Chezy coefficient based on d50, g

against the available data sets would increase their

sediment density, qs the density of the bed material,

predictive capability, but the modifications would be

q the density of water, l a ripple factor, and sb,wc the

weighted by the particular data sets. For example the

field data considered here only encompassed one

bottom shear stress due to the waves and current. The

median grain size (0.18 mm; i.e., fine sand).

first part of the above expression represents a trans-

At the present time, there is no well-established

port parameter, whereas the second part (the expo-

transport formula that takes into account all the differ-

nent) is a stirring parameter. The ripple factor, which

ent factors that control longshore sediment transport

indicates the influence of the form of the bottom

in the surf zone, although the VR evidently accounts

roughness on the bed load transport, is expressed as,

for many of those factors. A complete formula should

C 1:5

quantify bed load and suspended load, describe ran-

l

C90

dom waves as well as the effects of wave breaking,

and include transport in the swash zone.

where C90 is the Chezy coefficient based on d90,

which is the particle diameter, exceeded 10% by

weight. The combined shear stress at the bed (sb,wc)

Acknowledgements

induced by waves and current is (valid for a 90 angle

between the waves and current),

The research presented in this paper was carried

!

1 u0 2

out under the Coastal Inlets Research Program of the

sb;wc sb;c 1

n

2

V

U.S. Army Corps of Engineers. Permission was

granted to N.C.K. and H.C.M. by the Chief of

in which sb,c is the bed shear stress due to current only

Engineers to publish this information. Additional

and uo the maximum wave orbital velocity near the

support from the Swedish Natural Science Research

bed. The coefficient n is given by,

Council is also acknowledged (M.L. and A.B.).

sffiffiffiffiffi

fw

nC

2g

Appendix A. Longshore sediment transport for-

mulas

To calculate the suspended load, Bijker (1967)

A.1. Bijker formula (1967, 1971)

assumed that the bedload transport occurred in a

bottom layer having a thickness equal to the bottom

Bijker (1967) modified the Kalinske Frijlink for-

roughness (r). The concentration of material in the

mula (Frijlink, 1952) for bed load together with Ein-

bed load layer (cb; assumed to be constant over the

stein's method for evaluating the suspended load

thickness) is:

transport to be applied in a coastal environment. Thus,

Bijker's formula, popular among European engineers,

qb;B

rffiffiffiffiffiffiffi

cb

takes into account both waves and currents. The bed

sb;c

load transport rate ( qb,B; in m3/s/m, including pores)

r

6:34

q

is calculated from,

The concentration distribution is obtained from,

!

! pffipffiffiffiffiffi

ffi

V pffiffiffi

0:27s 1d50qg

w q

r h z j sb;wc

qb;B Ad50

g exp

cz cb

lsb;wc

C

hr z

where A is an empirical coefficient (1.0 for non-

where z is the elevation, h the water depth, w the

sediment fall speed, and j von Karman's constant. By

breaking waves and 5.0 for breaking waves), d50 the

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