CressHelp - Wind waves and swell - Wave / structure interaction - Overtopping

Cress Help - Wind waves and swell - Wave / structure interaction - Overtopping - Vertical structures - Z15.1

Overtopping over vertical wall

General introduction

The first part of this calculation rule gives equations to determine the amount of wave overtopping of vertical structures such as lock gates and openings in the defence that can be closed when there are high water levels (in Dutch: coupures). It also includes walls on quays, dikes or on shallow forelands (with or without berms).

General equations used:

For breaking waves :

(equation 1)

For non-breaking waves :

(equation 2)

and

(equation 3)

(equation 4)

With :

(equation 5)

In which :

g = acceleration of gravity = 9.81 [m/s2]
Hs = significant wave height [m]
hc = crest height of the wall in relation to the slack water line (SWL) [m]
L0p = wave length in deep water [m]
qnb = overtopping flow for non-breaking waves [m2/s]
qb = overtopping flow for breaking waves [m2/s]
q = normative overtopping flow for the situation [m2/s]
s0p = wave steepness [-]
Tp = peak period [s]
tan(a) = angle of slope of a quay or berm [-]

gtotal = product of all reduction factors [-]

The reduction factors and tan (a) depend on the type of structure.