Full-scale experimental study on wave overtopping at stepped revetments

Stepped revetments limit wave overtopping effectively. Small-scale studies provided insights in the design of crest-levels and step geometries of these structures. The validation of these insights at large scale, along with the analysis of individual overtopping volumes, is required to formulate design recommendations. This paper investigates wave overtopping rates and individual overtopping volumes at stepped revetments by means of full-scale flume experiments. Two cross-sections, each with a slope of 1:3, were studied with uniform step heights of 0.17 m and 0.50 m. The revetments reduced wave overtopping rates in comparison to smooth dikes, resulting in influence factors for roughness (gamma(f)) between 0.43 and 0.73. An empirical formula for gamma(f) is proposed with which the wave overtopping rate at stepped revetments can be estimated. Previous small-scale studies underestimate gamma(f) of this study by 2-31 %. Individual overtopping volumes were described by a Weibull distribution, revealing a higher median shape factor (b=1.63) for stepped revetments compared to breakwaters, smooth dikes or vertical walls.

Automated summary

Stepped revetments effectively limit wave overtopping and reduce wave overtopping rates compared to smooth dikes, with influence factors for roughness ranging from 0.43 to 0.73. An empirical formula is proposed to estimate the wave overtopping rate at stepped revetments. The study also found a higher median shape factor for individual overtopping volumes at stepped revetments compared to breakwaters, smooth dikes, or vertical walls.