Analysis of wave overtopping and dissipation mechanisms on stepped coastal embankments

Abstract

Coastal protection structures have been widely developed using diverse engineering approaches to mitigate wave over-topping and enhance hydraulic resistance through increased surface roughness. This study examines the effectiveness of stepped embankment configurations in augmenting surface roughness and reducing wave overtopping rates. A series of controlled hydraulic model experiments were conducted to evaluate the performance of stepped-surface embankments in comparison with conventional smooth-surfaced configurations. Wave overtopping characteristics were systematically investigated under a range of wave conditions, with incident wave periods varying from 5 to 15 s. The results demonstrate that the wave energy dissipation performance of both simple-stepped and composite-stepped embankments is strongly influenced by step height and geometric configuration. In contrast, smooth-surfaced embankments consistently exhibit the highest overtopping rates, indicating limited dissipation capacity. Based on the experimental findings, simple-stepped embankments are recommended for application in relatively shallow water conditions, whereas composite-stepped config-urations are more suitable for deeper coastal environments, where enhanced dissipation is required. The study provides a scientific basis for optimizing coastal protection design by integrating hydraulic performance with considerations of envi-ronmental compatibility and structural resilience. Furthermore, the insights into wave-structure interactions over stepped geometries contribute to the advancement of more efficient and sustainable coastal engineering practices.