Development of an Early Warning System to Mitigate Dredging Impacts on Coastal Ecosystems

The implementation of Early Warning Systems (EWS) is a highly effective approach to mitigating the impacts of dredging activities. These systems combine predictive numerical models and real-time data to forecast sediment dispersion and assess potential impacts on marine species and habitats protected under the EU Habitat Directive. As part of the Renovate research project, an EWS was developed for the coastal area of Civitavecchia (northeastern Tyrrhenian Sea, Italy) to address the effects of dredging activities related to new port infrastructure on Posidonia oceanicameadows and coralligenous habitats located within Sites of Community Importance (SCIs) near the port. During the initial phase of development, the EWS incorporated a hydrodynamic model and a wave model to analyze the coastal hydrodynamic environment. Both models employ a finite-difference curvilinear grid, enabling high spatial resolution near the shoreline while maintaining lower resolution offshore. This configuration facilitates effective downscaling from Copernicus Marine System models, which operate at approximately 4 km spatial resolution. A distinctive feature of the EWS is its integration with two monitoring fixed stations located north and south of the port. These stations are designed to measure turbidity levels in areas affected by dredging operations. Each station is equipped with custom-assembled sensors capable of continuously monitoring physical, chemical, and bio-optical water parameters, supported by a real-time data acquisition and transmission system. The EWS is activated when turbidity levels detected by the monitoring stations exceed thresholds established by national or international regulations. Its predictive outputs enable the identification and planning of mitigation measures to address dredging impacts. To assess the direct effects of increased turbidity on protected habitats and species, the system incorporates risk indicators based on species-specific stressor tolerance curves and thresholds derived from targeted laboratory experiments. This study demonstrates how the Civitavecchia EWS can significantly enhance risk assessment and response strategies, providing a valuable tool for local stakeholders (such as the Port Authority of the Central-Northern Tyrrhenian Sea) and contributing to the strengthening of coastal resilience. This EWS integrates multidisciplinary data, models, and knowledge into a standardized governance framework, employing an ecosystem impact forecasting system inspired by the concept of a coastal digital twin.