Public Services

Wave Measurement

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 :


  • Spectral significant wave height Hmo
  • Maximum recorded wave height Hmax
  • Peak wave period Tp
  • Zero crossing wave period Tz
  • Mean wave direction
  • 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 (1994-2016)
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% 40% 0.35 5.26 1.75 [3.95] 2.83
2008
67% 39% 0.41 5.32 3.31 [12.26] 5.31
2009 79% 39% 0.52 5.11 3.34 [12.26] 5.45
2010 63% 75% 0.37 5.05 2.89 [3.64] 4.82
2011 94% 78% 0.17 4.90 2.29 [10.72] 3.52
2012 86% 77% 0.18 5.08 2.59 [10.5] 4.14
2013 75% 81% 0.15 4.99 1.72 [11.98] 2.70
2014 58% 61% 0.31 5.42 2.07 [3.66] 3.35
2015 75% 11% 0.47 4.50 1.86 [10.95] 2.96
2016 55% 70% 0.16 4.56 0.97 [8.57] 1.55

Wave Measurement at West Lamma Channel Station (1994-2016)
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
2009 97% 34% 0.36 7.19 2.81 [11.19] 4.47
2010 83% 47% 0.33 6.87 1.33 [10.10] 2.24
2011 72% 54% 0.29 6.07 2.81 [13.56] 4.34
2012 88% 60% 0.22 5.93 0.72 [5.97] 1.18
2013 98% 75% 0.15 5.45 1.79 [11.19] 2.84
2014 99% 51% 0.28 6.41 2.47 [11.7] 3.89
2015 75% 52% 0.27 6.57 1.76 [10.09] 2.77
2016 91% 39% 0.36 6.73 2.08 [5.83] 3.40

Note:

  1. The time in service refers to the time at which the recorder is operational.
  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/ Project Sections 3 (kmcheng@cedd.gov.hk or 2762 5556) of the Port Works Division.