Implementation of a Dynamic Wave Overtopping-Flooding Coupled System in a Cross-Scale Model

Coastal regions in Korea are densely occupied by artificial coastal structures, making them highly vulnerable to wave overtopping during extreme storm events. Even when water levels remain below the crest elevation, overtopping can induce significant coastal flooding. To address this, we developed a dynamic overtopping-flooding coupled system within the cross-scale SCHISM-WWM modeling framework. The system computes time-varying overtopping discharge at each model time step using the empirical formulations of EurOtop(2018), and transfers the resulting flow into the land domain, enabling the coupled interaction among waves, water levels, and coastal structures to be resolved in a unified modeling environment. The model was applied to Marine City, Busan, during Typhoon CHABA (1618). Simulated water levels and wave conditions were validated against tide-gauge and buoy observations, followed by comparison of inundation patterns with post-surveyed inundation marks. The results show that the system successfully reproduces the spatial characteristics of observed inundation with reasonable accuracy. The framework can be further extended to incorporate rainfall-runoff and sewer backflow processes, allowing for a fully integrated compound flooding modeling system.