Field and modeled data on wave attenuation over a mixed seagrass meadow

Seagrass meadows attenuate wave energy, contributing to coastal protection by reducing wave height and limiting sediment transport. This study quantifies the wave attenuation capacity of mixed-species seagrass meadows within a Mexican Caribbean reef lagoon. Field data were collected through simultaneous wave measurements along two cross-shore transects, with and without seagrass, at depths of 3–4 meters. Even when occupying less than 10% of the water column, seagrass meadows reduced significant wave height ( Hs ) by more than 30%, over a 250-meter section under calm wave conditions ( Hs ≈ 0.2 m, Tp ≈ 8 s). Using transect-specific morphological and initial wave data, wave propagation simulated with the IH-2VOF model confirmed that bottom-induced dissipation was negligible. The extended version, IH-2VOF veg , which accounts for vegetation effects, was used to estimate the drag coefficient ( Cd ) of the seagrass meadow. Assuming a plant width ( b v ) of 0.007 m, calibrated Cd values ranged from 0.9 to 2.8. A relationship between Cd and the vegetation Reynolds number was significant when outlier dissipation cases (outside the interquartile range) were excluded. Given that the meadow was composed of mixed species with different morphologies and epiphytic coverage, alternative values of b v were tested, showing their influence on both the estimated Cd and the coefficients in the Cd – Re relationship. This study highlights the relevance of seagrass meadows for wave attenuation under calm conditions, even with limited canopy occupation of the water column. It also underscores the challenges of accurately simulating wave dissipation in mixed-species meadows and defining generalized Cd relationships. • Wave data compare propagation over bare bottom and seagrass meadows. • The mixed seagrass meadow occupying <10% of the water column reduced Hs by 30%. • Cd estimated using a numerical model was related with vegetation Re number • Modeling mixed meadows is challenging due to variable vegetation traits and structure