Chapter V
Hydraulic Performance
64
𝑅 𝑢2%
𝐻 𝑠
= 𝐴ξ + 𝐵
Equation V-2
Where:
𝑅 𝑢2% : the run-up exceeded by 2% of waves.
𝜉
: the surf similarity parameter, also known as the Iribarren number 𝜉 =
tan 𝛼
√𝑠 0
𝑠 0
: the fictitious wave steepness. 𝑠 0 =
𝐻
𝐿 0
=
2𝜋
𝑔
𝐻
𝑇 2
𝐻 (𝑚) : the local wave height.
𝐿 0
: the theoretical wavelength of the offshore wave.
𝑇
: the period of wave.
TAW (2002a) presents equations for the determination of wave run-up in which the breaker
parameter, 𝜉 m−1,0 , is applied, calculated by using the spectral significant wave height (𝐻 𝑠 = 𝐻 𝑚0 )
Table V-2 TAW (2002) Approach Equations for Calculating Wave Run-Up2%
Formulae
Parameters
For the mean energy wave
period,𝑇 m−1,0 :
𝑅 𝑢2%
𝐻 𝑚0
= 𝐴𝛾 𝑏 𝛾 𝑓 𝛾 𝛽 𝜉 m−1,0
And with a maximum or upper boundary
for larger values of 𝜉 𝑚−1,0 of:
𝑅 𝑢2%
𝐻 𝑚0
= 𝛾 𝑓 𝛾 𝛽 (𝐵 − 𝐶/√𝜉 m−1,0 )
𝐻 𝑚0 : the spectral significant wave height.
𝛾 𝑏 : the berm factor.
𝛾 𝑓 : the roughness factor.
𝛾 𝛽 : the correction factor for oblique waves.
𝜉 m−1,0 : the breaker parameter where:
𝜉 m−1,0 =
tan 𝛼
√ 𝑠 m−1,0
=
tan 𝛼
√
2𝜋
𝑔
𝐻 𝑠
𝑇 m−1,0
2
𝑇 m−1,0 : the mean energy wave period.
𝐻 𝑠 : the significant wave height at the toe of the
structure.
𝑔: acceleration of Gravity.
The values for coefficients A, B and C in the two equations above that are presented in Table
V-3
Table V-3 The values for coefficients A, B and C in the two TAW (2002a) equations
Coefficients
Values with safety margin
Values without safety
A
1.75
1.65
B
4.3
4.0
C
1.6
1.5