Eurotop manual

Infram in the Netherlands performed the logistic operation of testing with the wave overtopping simulator.

After completion of the testing in Infram has installed the wave overtopping simulator on the crest of a dike and simulated a large number of overtopping discharges, which were taken on video. Elaborated videos have been placed on the overtopping website, www.

The videos have been prepared in the following way. The simulation of the overtopping events by the wave overtopping simulator occurred by choosing randomly volumes from the distribution.

Then the first three minutes of the steering file of one hour was taken, simulated and the test was recorded on video. It was judged that a video of three minutes would be long enough to give a good impression of a certain overtopping discharge, coupled to a certain wave height.

Figure 2. Videos were recorded from two locations, one at the down-slope looking upwards and one next to the wave overtopping simulator and looking downwards. Videos were processed in a way that they also show the distribution of overtopping wave volumes and the volume illustrated on the video. Figure 2 gives a snapshot of a video taken from the downslope. The actual overtopping wave volume shown on the video is marked by a red square and amounts about l per m.

The video gives an impression of how many waves overtop in three minutes, what overtopping wave volumes they reach and what the velocity and flow thickness is over the slope. Besides taking three-minute videos also specific overtopping wave volumes were captured, from l per m up to l per m. The objective of making the videos available is that people interested in wave overtopping may get a clear view of a given mean overtopping discharge.

Moreover, the videos can be used to make a judgement on whether these overtopping discharges can be tolerated, depending on the actual situation. These volumes exceed the capacity of the wave overtopping simulator and videos for these circumstances could not be made. Tolerable overtopping summarised in Tables Sea defences and breakwaters should withstand severe wave attack and are often armoured on the seaward side with rock, concrete units, or block revetments.

River dikes and small reservoir dams are often only protected by a grass cover, but wave heights in these situations are limited. Waves that overtop the structure may attack the crest and rear side of the structure. Such a rear side could be a grass covered slope dike , but might also be a promenade or other higher ground.

A breakwater with limited wave overtopping may have a rear face protected by smaller material than on the seaward side. In all such cases, however, the tolerable wave overtopping should not significantly damage the crest or rear side, regardless of structure type.

Suggestions for limits for wave overtopping for structural design are given in Table 1 Table 1. The level of tolerable overtopping for property and operation will be very site and structure specific. It is useful to recall that large incident wave heights may lead to large overtopping volumes, even if the mean overtopping discharge is quite small. And if a given overtopping limit is exceeded, it may lead to significantly larger overtopping volumes, perhaps destroying the property.

Table 2 suggests limits for wave overtopping for property behind the defence. Table 2. Some people may take risks, perhaps of injury or even of being drowned. At some sites, public access may however be restricted when severe storms are forecast, but in others this may not be possible. For those sites, people should be warned of potential hazards from wave overtopping.

A more focussed 'duty of care' will apply to staff who have a task to inspect and monitor the condition of sea defences during a storm surge. Breakwaters may be particularly dangerous in storms where people can be washed off. In some instances an operating authority may be able to exclude access, but at others the public may still be able to access under severe wave conditions, even when such overtopping could be dangerous for people.

Some coastal locations use seawalls and breakwaters for recreation such as the breakwater at Oostende, Belgium, Figure 3. Both in summer and winter, the breakwater allows access to people, indeed that is one of its functions. The crest is wide, has many places to sit, and is illuminated at night. Figure 3. New breakwater at Oostende, Belgium, with a main function of access for people. The weather forecast system was used to calculate mean overtopping discharge and maximum overtopping wave volumes for predicted wave conditions and water levels.

As soon as a condition is predicted to exceed the maximum overtopping volume of l per m, the breakwater is closed at low water preceding the expected high tide overtopping. Tolerable overtopping discharges and overtopping wave volumes for people and vehicles are summarised in Table 3. Table 3. Clear view of the sea. The second edition will have a largely extended EurOtop database with in total more than 17, tests. It will predict wave overtopping discharge as well as wave transmission and wave reflection.

It is also possible that a second ANN becomes available to predict wave overtopping. Therefore one is referred to that reference, as well as to EurOtop The first EurOtop Manual gave then a deterministic and probabilistic approach of the prediction formulae, by giving two similar formulae with different coefficients in the formulae. The probabilistic approach used the mean value for the coefficient, where for the deterministic way about one standard deviation was added to the coefficient.

Use the formula as given with the mean value of the stochastic parameter s. This should be done to predict or compare with test data. This is an easy semi-probabilistic approach with a partial safety factor; this is the mean value approach above, but now with the inclusion of the uncertainty of the prediction. In this paper, the formulae are given as a mean value approach.

The coefficient to be used in the formula for the design or assessment approach will also be given. An example of this approach is shown next for wave run-up and is followed throughout this paper. The probabilistic approach is not used in this paper. For a design and assessment approach one should use the value of 1. Wave run-up on very steep slopes up to vertical walls Dike slopes are often quite gentle, say gentler than But seawalls and concrete structures may have steeper slopes.

Very shallow foreshores may also give large breaker parameters and very large wave run-up, see EurOtop and EurOtop and Figure 4. But wave run-up for very steep slopes, without a shallow foreshore, will not be as high as the upper line in Figure 4. Due to the work of Victor it is possible to give a good prediction of waver run-up for steep slopes up to vertical walls, at relatively deep water no very shallow foreshore.

This investigation focussed on wave overtopping on very steep slopes and prediction formulae will be given in the next section. Calculations were performed for various slope angles. Figure 4 shows the equations for relatively gentle slopes and for the situation of very shallow foreshores, but it also shows the relative wave run-up calculated as described above for slopes of and steeper, up to the limit of a vertical wall.

The graph shows that a steeper slope gives smaller wave run-up. Figure 4 shows clearly the difference between a very shallow foreshore and steep slopes without significant wave breaking on a foreshore, but in both situations large breaker parameters will be found.

For application of wave run- up formulae one has to distinguish between the situation of no or limited wave breaking on a foreshore and very shallow foreshores. Unfortunately, no funds could be raised to update the web-based Calculation Tool with the new formulae in the present manual. The old calculation tool has therefore been removed from the website and is not available as a tool covering this new manual.

In parallel with this manual an Artificial Neural Network, called the EurOtop ANN, is available to predict mean overtopping discharge for all kind of structure geometries, given by a number of hydraulic and geometrical parameters as input.

The ANN and both databases are available for free and links are given on the website. In the future, other predicting neural networks may also become available. It will take only 2 minutes to fill in. Cookies on GOV. UK We use some essential cookies to make this website work.

Accept additional cookies Reject additional cookies View cookies. Hide this message. Contents Documents Details. Documents Updated wave overtopping and assessment manual EurOtop and calculation tool Bayonet GPE - summary 81KB PDF External link: EurOtop wave overtopping manual External link: Bayonet GPE calculation tool If you use assistive technology such as a screen reader and need a version of this document in a more accessible format, please email: enquiries environment-agency.

Details This new manual offers up-to-date guidance to help users more accurately predict the rate of waves overtopping sea defences. Published 26 February Is this page useful?