Modeling wave-vegetation interactions: the impact of seagrass flexibility and seasonal variability

Abstract. This study delves into the intricate dynamics between wave activity and marine vegetation, focusing on Posidonia oceanica meadows in the Mediterranean Sea along the Civitavecchia coastal zone (north-eastern Tyrrhenian Sea, Italy). Traditional modeling approaches often oversimplify wave-vegetation interactions and overlook the necessity for robust in-situ observational systems, which can lead to inadequate representations of the dynamic environments where seagrasses thrive. The Digital Twin modelling framework presents a compelling solution, offering comprehensive insights that enhance decision-making for coastal management. We advance wave-vegetation modeling by integrating a refined seagrass representation that encompasses flexibility, seasonal growth dynamics, and phenotypic traits, all informed by site-specific measurements. Applying this model to the Civitavecchia coast demonstrated that integrating observed seasonal variability into the numerical model was crucial for obtaining realistic results. This revealed a mean monthly wave damping capacity variation of up to 10 %, intricately driven by seasonal growth dynamics. Spatial assessments unveiled wave height reductions ranging from 10 % to 40 %, with an average attenuation of 18 % across Sites of Community Importance and 24 % for seagrass traits over rocky substrate. These findings offer valuable insights into the role of seagrasses as nature-based solution, facilitating more effective coastal management strategies and guiding restoration efforts in vulnerable marine ecosystems.