ERDC/CHL CHETN-I-67
June 2003
Although they had run some tests with
Table 2
waves traveling midway between west and
Maximum Average Wave Heights in Box
Areas
southwest (equivalent to west-southwest or
θ = 210 deg), these waves did not prove to
Parameter
PP Boxes
CD Boxes
be worse than the southwest waves ( θ =
Existing Configuration
225 deg). The largest waves are now
T = 6 sec
0.31 m (Box 5)
0.30 m (Box 11)
traveling to the west (blue, dash line). The
T = 10 sec
0.37 m (Box 6)
0.29 m (Box 11)
difference in wave height for waves
T = 16 sec
0.34 m (Box 6)
0.26 m (Box 10)
traveling to the west and waves traveling to
Authorized Configuration
the southwest decreases as wave period
T = 6 sec
0.33 m (Box 5, 6)
0.23 m (Box 8)
increases. For T2 and waves going to the
T = 10 sec
0.38 m (Box 6)
0.20 m (Box 10)
PP, the largest waves are traveling to the
T = 16 sec
0.30 m (Box 6)
0.21 m (Box 10)
west.
The CGWAVE model provided 421 wave heights along the 481-m- (1,578-ft-) long T1 and 610
along the 672-m- (2,205-ft-) long T2 transect. Wave height statistics are again summarized in
Table 1 for all wave conditions along the two transects. Based on the data, the average wave height
along T1 will be in the range of 0.27 0.01 m with 95 percent confidence. The average wave height
along T2 will be in the range of 0.24 0.01 m with 95 percent confidence.
As before, a more meaningful analysis is obtained by looking at the boxes near the high use areas in
the vicinity of the PP and CD. Figure 17 shows the H for the authorized configuration for the three
wave periods. The maximum wave heights occur for waves traveling to the west for both PP and
CD boxes. This represents a change from the existing configuration for the CD boxes where the
maximum heights occurred for a wave direction to the southwest.
Again, the H Max and their locations from Figure 17 are shown for the PP and CD boxes in Table 2.
Averaged over all PP boxes, the maximum average wave heights H All = 0.24, 0.25, and 0.20 m for T
= 6, 10, and 16 sec, respectively. All maximum values are for waves traveling to the west.
Averaged over all CD boxes, the maximum average wave heights H All = 0.19, 0.18, and 0.20 m for T
= 6, 10, and 16 sec, respectively. All maximum values are for waves traveling to the west. Finally,
the 95 percent confidence interval for average wave height inside all boxes for all wave conditions is
0.13 0.02 m in both the PP and CD areas.
COMPARISON OF BREAKWATER CONFIGURATIONS: In the previous plots, the
CGWAVE predicted wave heights H were shown for each transect, box, wave condition, and
breakwater configuration. In this section, a comparison of the predicted wave heights between the
existing 122-m (400-ft) gap and the authorized 91-m (300-ft) gap breakwater is presented. Because
of the variability along the two transects (as previously discussed), only the wave heights in the
boxes are compared.
Wave height differences HD between the existing (E) and authorized (A) configurations are shown
for the PP and CD boxes in Figure 18. Negative differences indicate that the existing configuration
has a smaller predicted wave height than the authorized configuration. Therefore, only the positive
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