296
L. Erikson et al. / Coastal Engineering 52 (2005) 285302
10-3
101
C1
B8
10-4
100
10-5
10-1
10-6
10-2
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
Frequency (Hz)
Frequency (Hz)
10-3
101
B9
B10
10-4
100
10-5
10-1
10-6
10-2
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
Frequency (Hz)
Frequency (Hz)
Fig. 7. Power spectra of swash depths measured at SWS. (N.B. Vertical scale differs between panels).
the maximum run-up length. The mid-swash position
yhb=3). This ratio (yhb=0.60yhu) was employed in the
represented by x*=0.5 was used in all simulations as
model so that average leading edge back-wash heights
were in the range of 1 to 2.4 cm. The results in Fig. 9
suggested by Hughes (1995). The maximum run-up
are with yhb=0.6yhu for all cases except B9 where
height, zm, in Eq. (14) was calculated with Eq. (6) in
combination with the friction factors by either Eq. (7)
yhb=0.75yhu. The greater relative back-rush height
or (8). Mean values (for all waves of each case) were
resulted in a decrease of the maximum run-up from
found to be yhu=2 cm for cases C1 and B8 and yhu=4
0.73 m to 0.48 m, which is significantly better
compared to the measured run-up length of 0.49 m.
cm for cases B9 and B10. Measurements obtained
For cases with significant swash interaction, the
from both video images and the most landward
model is quite sensitive to changes of yhb. To illustrate
2 cm to 3 cm. Discrepancies between measured and
this point, maximum calculated run-up lengths nor-
predicted values differ on a case-by-case basis, with
malized by measured maximum run-up lengths are
the maximum difference less than 1.8 cm.
that the maximum run-up length is best estimated with
and field studies and found that the thickness of the
yhb/yhu=0.60 for cases B8 and B10, while yhb/
up-rush, yhu, was consistently greater than the back-
yhu=0.75 yields the best estimate for case B9. For
wash height, yhb. Based on Atlantic Coast field data,
case C1, where there is little swash interaction, any
value of yhb/yhuN0.4 yields equally good results with
Holland and Puleo (2001) estimated that the back-
wash height was 60% of the up-rush (yhu=5 cm and
respect to the maximum run-up length.
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