Impact‑based extreme‑wave intensity scale for high‑resolution coastal forecasting

Extreme wave events are recurring meteorological and oceanographic hazards that have a significant impact on coastal regions, leading to infrastructure damage, beach erosion, and adverse effects on fisheries and port operations, resulting in substantial economic losses in Chile. In recent decades, both the frequency and intensity of extreme wave events have increased, and this trend is projected to continue due to climate change, making Chile's extensive coastline particularly vulnerable. In this context, having access to accurate and high-resolution coastal wave forecasting is crucial for coastal users and stakeholders involved in assessing and managing the risks associated with extreme wave events. Here, we present a high-resolution coastal wave forecasting system, which is validated using in situ measurements in Valparaíso Bay. Additionally, an impact-based extreme wave intensity scale has been developed to improve risk communication, support the issuance of official early warnings, and enhance emergency response. A five-category scale, derived from a qualitative analysis of historical impacts on beaches and coastal infrastructure, is fully integrated into the forecasting system. Video cameras have been installed to provide real-time broadcasts of the coastline, facilitating continuous monitoring of wave conditions and their impacts during extreme wave events. Furthermore, the information is disseminated through a dedicated public website and various social media platforms to effectively communicate warnings and promote preventive actions. Key national public institutions responsible for issuing warnings and managing emergencies participate in the information flow, thereby strengthening risk governance and public decision-making, and increasing confidence in the reliability of the coastal wave intensity forecasts.