Crossing seas may be present when sea and swell waves come from different directions. The effect of crossing seas on wave overtopping over a smooth 1:3 slope was investigated in the HYDRALAB+ project CrossOver. Tests were performed in Deltares' large Delta basin, a basin that has two multi-directional wave generators. Overtopping was measured in six boxes. Analysis is ongoing. A paper and presentation (paper (1.2 MB), presentation (92 MB)) on the distribution of overtopping wave volumes in crossing seas is available, also describing the set-up of the tests.
A first model investigation was performed at DHI, Denmark, under the Hydralab III programme of the EU and with leader the University of Aachen, Germany. Subject was the influence of currents on wave overtopping at 1:3 river dikes. A second, but similar, investigation was perfomed for the German KFKI on 1:6 sea dikes. A first paper of the investigation and results is available for download. A detailed analysis is available in a report.
A large FP6 research programme coordinated by HR Wallingford, UK, on Integrated Flood Risk Analysis and Management Methodologies. Van der Meer has been involved in defining failure modes for flood defences under wave attack and wave overtopping. See www.floodsite.net.
This research project on wave overtopping was developed by Van der Meer in cooperation with Ghent University, Belgium, as coordinator. A database was developed during the project, contained more than 10,000 wave overtopping tests from all over the world. An Artificial Neural Network was then constructed by Delft Hydraulics, which is able to predict the wave overtopping discharge for all kind of coastal structures. A paper was written by Van der Meer on how to apply the Neural Network in engineering work. An extended database and improved Neural Network is now available through the University of Bologna and more information can be found in the EurOtop overtopping manual.
In DELOS engineers, biologists and economists met each other. The project dealt with environment friendly design of low-crested structures. The final result of the project were guidelines for design. Van der Meer developed in cooperation with the universities of Rome and Bologna new design formulae for wave transmission over low-crested structures.