Abstract
The purpose of this study is to improve the effect of gentle slope-type seawall on prevention of wave overtopping. With this in view, the experiments on irregular wave overtopping are carried out for a gentle slope and roughened seawall. In these experiments, artificial wave furrows are used as a roughness. Consequently, the effective arrangement and shape of artificial wave furrows are clarified to prevent wave overtopping. In addition, the Weibull distribution can be applied to approximately the frequency distribution of wave overtopping rate over a gentle slope and roughened seawall.