Floating wetlands, as an innovative form of ecological engineering, offer multiple environmental benefits, including shoreline erosion mitigation, water quality improvement, and habitat restoration. In recent years, their prospective applications in dynamic coastal zone management and climate adaptation have garnered growing attention. Among various contexts, the deployment of floating wetlands along highly erosive, silt-mud coastlines subject to intense wave activity presents both engineering challenges and ecological opportunities. However, research on the hydrodynamic interactions between floating wetland structures and incident waves in such high-energy coastal environments remains limited. In particular, a systematic understanding of wave attenuation performance, structural response, and long-term stability is lacking, thereby constraining broader implementation within coastal engineering practice.

This study proposes a novel floating wetland structural system designed for application along erosion-prone silty coastlines. The Sheyang coast in Jiangsu Province, China—characterized by high sedimentation rates and severe coastal erosion—was selected as the representative study site. A series of laboratory-scale physical model experiments were conducted in a wave flume to evaluate the wave damping capacity and mechanical stability of the floating wetland system under varying wave conditions. The research systematically investigated the effects of key structural parameters—including the relative width of the wetland array (W/L, where W is the array width and L is the incident wavelength), configurations of bottom-mounted damping components, and spacing between modular units—on wave attenuation efficiency and overall system stability.

Experimental results showed that the proposed floating wetland exhibited excellent wave attenuation performance under short-period wind waves (wave period ≤ 1.5 s), with energy dissipation coefficients exceeding 60%. To enhance performance under long-period wave conditions, auxiliary damping components such as bottom pontoons and flexible plates were integrated into the design. These bottom-mounted elements markedly improved the system’s damping capacity. Notably, flexible pontoons outperformed rigid structures, owing to their adaptive response to wave motion and energy dissipation through elastic deformation. For instance, under a wave height of 0.32 m and a period of 3.00 s, the inclusion of flexible damping elements increased the wave attenuation coefficient by approximately 15% compared to configurations lacking such components.

Further analysis indicated that the relative width of the wetland array (W/L) is a critical determinant of wave attenuation performance. When W/L exceeded 0.48, wave attenuation coefficients consistently remained above 60% across all tested module spacings under short-period wave conditions, signifying robust energy dissipation. Conversely, for W/L values below 0.48, wave transmission coefficients stabilized at higher levels, while attenuation coefficients exhibited greater variability. These results suggest that narrower array configurations are less effective under long-period wave conditions, underscoring the need for site-specific geometric optimization.

The study also assessed the mechanical response of wetland arrays under different module spacing scenarios. As the spacing between individual wetland modules increased, lateral displacement of the array significantly intensified, accompanied by a sharp rise in mooring line tension. In the configuration with 3-meter spacing, peak mooring tension occurred more frequently and was approximately four times higher than that in the 1-meter spacing scenario. Increased spacing also induced greater internal structural stresses, potentially compromising the system's long-term durability. These findings highlight the necessity of integrative design considerations encompassing hydrodynamic conditions, structural configuration, and anchoring systems to ensure long-term resilience.

In conclusion, the proposed floating wetland system offers a viable solution for ecological enhancement and shoreline protection along silty, erosion-prone coastlines. Its demonstrated ability to attenuate wave energy and maintain structural integrity under challenging hydrodynamic conditions supports its integration into broader coastal zone management frameworks. Moreover, by enabling multifunctional use of intertidal spaces, such systems advance the vision of creating “dynamic coastlines” that are both ecologically functional and resilient to environmental change. Future research should prioritize long-term field validation and explore synergies between floating wetlands and other nature-based or engineered coastal defense strategies to fully realize their ecological and protective potential.