A method has been developed to estimate wave overtopping discharges for a wide range of coastal structures. The prediction method is based on Neural Network modelling. For this purpose use is made of a data set obtained from a large number of physical model tests (collected within the framework of the European project CLASH, see e.g. [Steendam, G.J., Van der Meer, J.W., Verhaeghe, H., Besley, P., Franco, L. and Van Gent, M.R.A. (2004). The international database on wave overtopping. World Scientific, Proc. 29th ICCE, vol. 4, pp. 4301-4313, Lisbon, Portugal.]). Moreover, a method was developed to obtain confidence intervals for the overtopping predictions of the neural network.

For design, safety assessment and rehabilitation of coastal structures reliable predictions of wave overtopping are required. Several design formulae exist for dikes, rubble mound breakwaters and vertical breakwaters. Nevertheless, often no suitable prediction methods are available for structures that do not resemble rather standard shapes. In the European research project CLASH a method is developed to provide a generic design tool to estimate wave overtopping discharges for a very wide range of coastal structures. The paper gives results from the CLASH project on this subject. It is focused on the extensive database gathered (see Verhaeghe et al., 2003), the neural network (see Pozueta et al., 2004) that has been developed on the basis of this database, and on applications of both.

A method has been developed to estimate wave overtopping discharges for a wide range of coastal structures. The prediction method is based on the technique of Neural Network modelling. For this purpose use is made of a data set obtained from a large number of physical model tests. Moreover, a method was developed to obtain the confidence intervals around these predictions.

The stability of the rear side of rubble mound structures under wave attack has been studied by means of physical model tests in a wave flume. The damage at the rear side slope has been measured for several structure types while the main hydraulic and structural parameters affecting the damage have been varied. The data-set was analysed to obtain estimates of the amount of damage for a wide range of conditions. By using estimates of velocities at the crest during wave overtopping events the amount of damage at the rear-side slope could be predicted. The estimates of velocities can be obtained by using an approach that estimates fictitious wave run-up levels for a situation as if the structure was non-overtopped. Depending on the acceptable damage level the required stone diameter at the rear side can be estimated based on the obtained prediction formula.