Development and validation of an Early Warning System for coastal flooding operating on a Mediterranean urban beach

Abstract. This study presents an Early Warning System (EWS) for coastal flooding that integrates wind, wave, and sea level forecasts which are validated using in situ records. The system employs the SWAN spectral wave model to simulate nearshore hydrodynamics while an empirical approach is used to assess Total Watel Level (TWL) exceedances over a user-defined morphological threshold, deriving from repeated topographic surveys. This approach utilizes widely used empirical methods for wave run-up estimation and makes use of the most effective one after calibration. The performance of the EWS is assessed through seven monitored surge events of varying magnitude and hydrodynamic conditions, demonstrating strong agreement between projected TWL exceedances over predefined morphological thresholds, particularly under high-energy wave conditions. Minor discrepancies are noted during events with marginal TWL exceedances over short durations. Results underline the system's potential as a valuable tool for coastal hazard assessment and risk management, with future improvements focusing on appropriate updates of the beach morphology and the integration of suitable numerical techniques and machine learning algorithms.