Cress Help - Wind waves and swell - Waves near the shore - Reflection - A14.2

Vertical constructions

The calculation rule gives the reflection coefficient for various structures: smooth impermeable slopes, slopes with rubble or concrete elements and vertical structures. Reflection occurs if the bottom or angle of slope is steeper than ca. 1:15, and the angle of wave approach is greater than ca. 10 degrees. (This is the angle between the wave crest and the normal to the bank or the angle between the wave direction and the line of the dike).

Vertical structures (based on measuring points):

    (equation 1)

    (equation 2)

Moreover:

    (equation 3)

and

    (equation 4)

and

    (equation 5)

in which:

  • g = acceleration of gravity = 9.81 [m/s2]
  • Hs = significant incoming wave height [m]
  • Hsr = significant reflected wave height [m]
  • hc = crest height in relation to SWL [m]
  • KR = reflection coefficient [-]
  • L0p = wave length in deep water based on the peak period [m]
  • tan(a) = equivalent angle of slope [-]
  • z Op = breaker parameter [-]

References:
Smooth impermeable slope :

[a] Petit, H.A.H., Golf reflectie, WL, concept notitie, nov. 1993.

Rubble and concrete elements:

[b] Allsop, N.W.H. and S.S.L. Hettiarachchi, Design, construction and performance of wave absorbing structures, HR Wallingford, Report OD 89, Feb. 1989.
[c] Goda Y. 1985, Random seas and design of maritime structures, Univ. of Tokyo Press.