Simple Physics-Based Rip Current and Shore-Break Wave Hazard Predictors for Beaches in Southwest France

Abstract Sandy beaches are attractive yet potentially dangerous environments due to physical hazards in the surf zone. The most severe natural hazards are rip currents and shore-break waves, which form under varying wave, tide, and morphological conditions. This study introduces two simple, physics-based models to forecast channel rip current flow speed V and shore-break wave energy Esb . These models were applied to La Lette Blanche, a high-energy meso-macro-tidal beach in southwest France, where both physical hazards coexist. Lifeguard-perceived hazard data collected hourly from July to August 2022 during patrol hours (11 AM–7 PM) were used to calibrate the models. This data also informed a 5-level hazard scale, from 0 (no hazard) to 4 (maximum hazard). The models accurately predict hazard levels, accounting for tidal and wave influences. Requiring only basic beach morphology metrics, this approach offers a promising tool for forecasting surf-zone hazards on beaches with minimal morphological data and available wave forecasts.