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The Port Works Division has been maintaining a long-term wave monitoring programme since 1994. Two monitoring stations have been set up in the harbour near Kau Yi Chau and at the West Lamma Channel. The collected wave data is used to set up wave models for predictions of extreme wave conditions in the harbour for the design of marine structures.
The following parameters are provided from the outputs of the recorders :
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Spectral significant wave height Hmo
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Maximum recorded wave height Hmax
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Peak wave period Tp
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Zero crossing wave period Tz
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Mean wave direction
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Average water depth |
The average recorded water depths at Kau Yi Chau and West Lamma Channel wave stations are respectively about 9m and 10m. A summary of the wave measurement is given below.
Wave Measurement at Kau Yi Chau
Station (1994-2008)
| Year |
Time in Service
(%) |
Calm Period
(Hmo<0.3m) |
Average
Hmo(m) |
Average
Tp (s) |
Maximum
Hmo (m) [Tp (s)] |
Maximum Recorded
Hmax (m) |
1994 |
78% |
63% |
0.31 |
6.7 |
1.46 [9.1] |
2.45 |
1995 |
87% |
77% |
0.26 |
6.5 |
1.51 [11.6] |
2.68 |
| 1996 |
60% |
75% |
0.27 |
6.3 |
1.57 [11.6] |
2.38 |
| 1997 |
95% |
79% |
0.26 |
6.7 |
1.61 [11.6] |
2.68 |
| 1998 |
97% |
81% |
0.24 |
6.4 |
1.40 [9.1] |
2.92 |
| 1999 |
92% |
75% |
0.25 |
6.2 |
2.36 [9.9] |
3.75 |
| 2000 |
76% |
71% |
0.28 |
6.3 |
1.70 [9.1] |
2.33 |
| 2001 |
80% |
72% |
0.29 |
6.3 |
2.68 [10.7] |
3.87 |
2002 |
96% |
79% |
0.26 |
6.1 |
2.46 [11.6] |
3.42 |
| 2003 |
74% |
76% |
0.28 |
6.4 |
2.46 [12.8] |
3.44 |
2004 |
87% |
30% |
0.34 |
4.1 |
1.37 [9.5] |
2.21 |
2005 |
84% |
58% |
0.31 |
5.62 |
1.73[13.21] |
2.65 |
| 2006 |
72% |
58% |
0.32 |
6.04 |
2.47[11.7] |
3.83 |
2007 |
51% |
41% |
0.35 |
5.26 |
1.75[3.95] |
2.83 |
2008 |
67% |
39% |
0.41 |
5.32 |
3.31[12.26] |
5.31 |
Wave Measurement at West Lamma
Channel Station (1994-2008)
| Year |
Time in Service
(%) |
Calm Period
(Hmo<0.3m) |
Average
Hmo(m) |
Average
Tp (s) |
Maximum
Hmo (m) [Tp (s)] |
Maximum Recorded
Hmax (m) |
| 1994 |
84% |
55% |
0.33 |
7.5 |
1.68 [9.1] |
2.42 |
| 1995 |
53% |
47% |
0.36 |
7.3 |
1.45 [3.9] |
2.47 |
| 1996 |
41% |
56% |
0.32 |
7.1 |
1.71 [11.6] |
2.83 |
| 1997 |
70% |
60% |
0.28 |
6.7 |
2.52 [5.8] |
3.99 |
| 1998 |
34% |
51% |
0.32 |
8.0 |
1.08 [12.8] |
1.93 |
| 1999 |
51% |
50% |
0.33 |
7.3 |
3.28 [9.9] |
4.68 |
| 2000 |
72% |
38% |
0.38 |
6.5 |
1.95 [9.9] |
3.01 |
| 2001 |
77% |
45% |
0.35 |
6.6 |
3.03 [10.7] |
4.01 |
| 2002 |
27% |
51% |
0.33 |
7.4 |
2.29 [10.7] |
3.41 |
| 2003 |
96% |
38% |
0.37 |
6.9 |
3.38 [12.8] |
5.45 |
| 2004 |
75% |
32% |
0.37 |
6.4 |
1.59 [10.3] |
2.57 |
| 2005 |
89% |
43% |
0.35 |
6.89 |
2.01 [11.98] |
3.11 |
| 2006 |
77% |
41% |
0.37 |
7.29 |
2.99 [10.95] |
4.64 |
| 2007 |
82% |
47% |
0.34 |
6.95 |
2.29 [7.79] |
3.69 |
| 2008 |
95% |
41% |
0.36 |
7.24 |
3.49 [13.93] |
5.46 |
Note:
| 1. |
The time in service refers to the time at which the recorder is operational.
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| 2. |
The peak period Tpof the maximum Hmo, is shown in square brackets. |
The wave measurement over these periods reflected that
the prevailing wave directions in the measurement
locations are the south and southeast, and extreme
wave heights are generally aligned with the presence
of tropical cyclone events. It should be noted that
the recorded spectral significant wave height Hmo
at these two wave stations may be taken to be approximately
the same as the significant wave height H1/3
for design purpose. More details of these data can
be obtained from Civil Engineering and Development
Department if required.
For further information about the wave measurements
at the two monitoring stations mentioned above, please
contact
Senior Engineer/ Projects 3(stevensktong@cedd.gov.hk
or 2762 5553)
of the
Port Works Division.
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