Koen Van Doorslaer, Julien De Rouck, Jentsje Van der Meer


A second edition of the EurOtop manual, a manual on wave overtopping of sea defenses and related structures, became available as pre-release in October 2016 on the website One of the improvements in this manual is based on the material in the current paper: how wave walls can reduce wave overtopping discharges. The base data set for the original advice in the previous EurOtop from 2007 is compared to the new developed procedures and new (unpublished) data collected in the wave flume of Ghent University. The comparative study shows that the differences are due to hydraulic differences in the test program. The original dataset from 1994 has tests with the still water level SWL both above and below the foot of the wall and was analyzed with an average slope analysis, where the UGent dataset only has tests with SWL below the foot of the wall and the small wall on top of the dike slope did not influence the average slope so that the actual slope could be used. The reduction factors deduced in analyzing the UGent datasets also work well for part of the original dataset, but not the other way around. The advice in the second edition of the EurOtop is thus to use the reduction factors by the UGent data analysis for wave walls above SWL, where the method proposed in the first edition can still be used for wave walls that have their foot below SWL. Both methodologies are explained in this paper.


Wave overtopping; reduction factor; wave wall; breaking waves; non-breaking waves; storm wall

Full Text:



Den Heijer, F., 1998. Golfoverslag en krachten op vertical waterkeringsconstructies. Rapport H2014 (in Dutch).

EurOtop, 2007. Wave Overtopping of Sea Defences and Related Structures: Assessment Manual. Pullen, T., Allsop, N.W.H., Bruce, T., Kortenhaus, A., Schüttrumpf, H., van der Meer, J.W.

EurOtop, 2016. Manual on wave overtopping of sea defences and related structures. An overtopping manual largely based on European research, but for worldwide application. Van der Meer, J.W., Allsop, N.W.H., Bruce, T., De Rouck, J., Kortenhaus, A., Pullen, T., Schüttrumpf, H., Troch, P. and Zanuttigh, B.,

Mertens, T., De Wolf, P., Verwaest, T., Trouw, K., De Nocker, L., Coudere, K., 2009. An integrated master plan for Flanders future coastal safety. ASCE. Proceedings of ICCE 2008. pp. 4017-4028

TAW, 2002. Technical report. Wave runup and wave overtopping at dikes. Technical Advisory Committee on Flood Defence, Delft.

Van der Meer, J.W., 1997. Golfoploop en golfoverslag bij dijken. Rapport H2458 (in Dutch)

Van der Meer, J.W. and Bruce, T., 2014. New physical insights and design formulas on wave overtopping at sloping and vertical structures. ASCE Journal of Waterway, Port, Coastal & Ocean Engineering.

Van der Meer, J.W. and Janssen, J.P.F.M., 1994. Wave run-up and wave overtopping at dikes. ASCE. In: Wave forces on inclined and vertical wall structures, ed. N. Kobayashi and Z. Demirbilek, pp. 1-27. Also Delft Hydraulics Publication nuMBer 485

Van Doorslaer, K., De Rouck, J., Audenaert, S., Duquet, V., 2015. Crest modifications to reduce wave overtopping of non-breaking waves over a smooth dike slope. Elsevier, Journal of Coastal Engineering 101, pp. 69-88.

Victor, L., 2012. Optimization of the Hydrodynamic Performance of Overtopping Wave Energy Converters: Experimental Study of Optimal Geometry and Probability Distribution of Overtopping Volumes. PhD Manuscript, Ghent University.