Multi-sensor observations and modeling of wave swash on a low-tide terrace beach

This study presents the first application of the non-hydrostatic CROCO model to simulate surf- and swash-zone hydrodynamics over a week-long field experiment, combining LiDAR, camera, and ADCP observations. This approach enables validation of cross-shore wave transformation and run-up dynamics, showing that CROCO reproduces dominant swash components and extreme run-up events. Sensitivity analyses reveal a nonlinear coupling between [Formula: see text] and [Formula: see text]: small changes in period (≈ 1 s) significantly affect swash response, while increasing [Formula: see text] amplifies this sensitivity. Run-up increases with tide under low-energy conditions but decreases under high-energy conditions, reflecting interactions between incident and infragravity waves over low-tide terrace beaches. Frequency spreading, negligible at low energy, becomes important at higher energy levels. Model limitations include underestimation of infragravity tidal modulation, simplified bottom friction in the swash zone, and the absence of directional spreading (2DV configuration). Despite these, adjustments to [Formula: see text] and cross-shore comparisons confirm the robustness of key results. Overall, findings emphasize the combined role of wave energy, spectral spread, and water level, as well as depth-controlled morphology (e.g. surf-zone slope), in run-up prediction. The study demonstrates CROCO's potential for near-real-time applications and supports the development of site-specific, data-driven run-up parameterizations for coastal hazard assessment.