Parametric assessment of submerged horizontal plates to mitigate tsunami-like wave overtopping at vertical coastal revetments

초록

Tsunami-like wave overtopping can pose a significant external flooding hazard to coastal nuclear power plants. This study investigates the effectiveness of a submerged horizontal plate (SHP) in reducing overtopping at a vertical coastal revetment under solitary wave conditions. Hydraulic experiments were first conducted to examine the overtopping reduction mechanism for a fixed SHP configuration. Smoothed particle hydrodynamics (SPH) simulations were then validated against the experimental results and applied to a parametric assessment of SHP geometry and placement. The results show that overtopping reduction is governed mainly by forced wave breaking over the SHP, rather than by simple attenuation of the incident wave height. As the modified surf similarity parameter decreases, the breaker regime transitions from non-breaking to collapsing and plunging breakers, resulting in lower dimensionless overtopping discharge and higher overtopping reduction rates. The relative submergence depth and relative plate length are identified as the dominant parameters controlling forced breaking and overtopping reduction, whereas plate thickness and inclination have secondary effects. The detached distance affects the post-breaking transformation of the transmitted wave field. These findings indicate that SHPs can provide a practical means of reducing tsunami-like overtopping by dissipating wave energy before it reaches the revetment. The proposed breaker-based design approach can support preliminary performance-based design of coastal protection measures for flood-critical infrastructure. © 2026 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/

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