New Physical Insights and Design Formulae on Wave Overtopping at Sloping and Vertical Structures

J.W. van der Meer, Tom Bruce

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Mean wave overtopping discharge is a key design parameter for many coastal structures, typically designed to limit overtopping discharge to below a chosen admissible value. Dutch, German and UK design guidance from the 1990s was updated using results of research projects such as the EC CLASH project, and unified with the publication of The European Manual for the Assessment of Wave Overtopping, or “EurOtop” in 2007. This paper explores five technical issues not well-covered in EurOtop.
(i) For sloping structures, overtopping at low and zero freeboard conditions: new analysis brings together the conventional exponential formulae with the few reliable datasets including very low and zero freeboard. In doing so, early Dutch work from the 1970s was revisited. Weibull-type formulae are proposed, describing wave overtopping at slopes for the whole range Rc/Hm0 ≥ 0.

(ii) For vertical walls, EurOtop distinguishes overtopping responses depending upon whether wave breaking occurs, with non-breaking and breaking conditions described by exponential and power-law formulae respectively. Here, the governing equations are manipulated in such a way as to “reunify” the methods, enabling direct and intuitive comparison.

(iii) For overtopping at vertical walls under non-impulsive conditions, early work of Franco et al. and Allsop et al. diverge significantly for other than lower freeboards. This paper explores why these two reliable studies arrived at two such different predictors. By reanalysis of the original datasets augmented by further data from the CLASH database, a physical distinction based upon the nature of the foreshore is proposed and tested.

(iv) The prediction method for overtopping at composite vertical structures is reworked to enable the influence of the mound to be apparent, and to align with plain vertical wall formulae for smaller mounds. A new scheme is proposed which treats composite structures via a small adjustment to the new vertical wall approach proposed earlier.

(v) There is a vast literature on overtopping response at mildly-sloping structures, and substantial literature on vertical walls, but in the intervening range (approximately 1V:1.5H to 5V:1H) there is paucity of reported tests. Recently published Belgian data by Victor has enabled the development of a continuous prediction scheme spanning mild slopes, steep slopes and vertical structures without foreshore.
Original languageEnglish
JournalJournal of Waterway, Port, Coastal, and Ocean Engineering
Early online date2 Jul 2013
DOIs
Publication statusPublished - 2013

Keywords / Materials (for Non-textual outputs)

  • coastal engineering
  • breakwaters
  • coastal structures
  • overtopping

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