Full-scale experimental study on wave reflection and run-up at stepped revetments

Abstract

Stepped revetments are especially suitable in urban areas as they effectively limit wave overtopping whilst offering recreational benefits. A deeper understanding of wave-structure interactions facilitates optimised stepped revetment designs. Wave reflection and wave run-up processes also indirectly provide insights in the wave energy dissipation of stepped revetments. Only few studies have focused on wave reflection from stepped revetments, while the wave run-up process on stepped revetments was studied widely, yet only with small-scale wave flume tests and mostly with regular waves. As the wave overtopping rates in small-scale wave flume tests underestimate those measured in full-scale experiments, these studies are likely affected by scale. This paper investigates wave reflection from and wave run-up on 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. It was found that previous small-scale studies underestimate relative run-up heights by 31–51%. Empirical formulae were derived to estimate wave reflection coefficients and wave run-up heights of stepped revetments. Wave reflection and run-up processes are described and provide further insight in the functioning of stepped revetments.