Physical model tests to determine the roughness of stair shaped revetments

Stair shaped revetments are considered as an attractive alternative for traditional revetments since the surface roughness reduces wave overtopping resulting in a lower required crest height. The specific shape enables easy access from and to the water surface, enhancing the attractiveness for tourists and residents. To implement stepped revetments in the design of a seawall there is a need to quantify the roughness of a stair shaped revetment to predict wave overtopping rates. This paper describes research in which 2D physical model experiments were conducted in Deltares’ Scheldt Flume. Based on the obtained data a method to quantify the roughness coefficient of such structures is suggested.