217

Fig. B2. Irregular wave Test 8E: vertical structure of the mean longshore current at Y27.

point where the measured significant wave height

velocity structure. ADV 6 was located at the position

began to decrease at the highest rate Zsee Fig. 14a..

of incipient wave breaking.

This occurred at the location *x *s 13.1 m, where

Fig. B2 shows the vertical structure of the mean

the longshore-averaged significant wave height

longshore current for the irregular wave case ZTest

was 0.21 m.

8E.. The mean longshore current in this case is also

Estimates of the position of the mean water line

rather uniform with depth. In the inner surf zone

are *x *s 2.1 m for the regular wave case and *x *s 2.4

ZADV 1 through 6., there is a slight increase in

m for the irregular wave case. It should be noted that

current speed with distance from the bed, and the

the cross-shore position of the mean water line could

vertical variations are similar to those measured for

only be estimated with an accuracy of approximately

the regular wave case. In the outer surf zone ZADV 7

"0.1 m. Therefore, the estimates of maximum wave

and 8., the mean velocity is relatively invariant with

set-up are only accurate within "0.003 m.

depth. This trend is different from that in the regular

wave case, where the mean velocity decreased

slightly with increasing distance from the bottom.

However, in the regular wave case, no waves were

breaking at ADV 7 and 8; whereas in the irregular

wave case, some wave breaking occurred in this

Fig. B1 shows the cross-shore variation in the

region.

vertical structure of the mean longshore current for

the regular wave case ZTest 6N.. In general, the

mean longshore current is rather uniform with depth.

In the inner surf zone ZADV 1 through 5., there is a

slight increase in current speed with distance from

the bed, and outside the surf zone ZADV 7 and 8. a

Brebner, A., Kamphuis, J.W., 1963. Model tests on the relation-

ship between deep-water wave characteristics and longshore

slight decrease in current speed with distance from

the bed. Visser Z1991. measured similar trends in the

Kingston, Ontario, Canada, 28 pp.

vertical velocity structure using regular waves. Pu-

Dalrymple, R.A., Dean, R.G., 1972. The spiral wavemaker for

trevu and Svendsen Z1992. presented a theoretical

littoral drift studies. Proc. 13th Int. Conf. Coastal Eng., Van-

model that predicts similar trends in the vertical

couver, Canada. pp. 689705.