Session: 06-03-01 Fluid-Structure, Multi-body and Wave-body Interaction/Professor Calisal Honoring Symposium

Submission Number: 157335

Experimental Study on Wave Attenuation by Buoyant and Flexible Vegetation for Sustainable Coastal Protection 

Coastal regions face growing threats from erosion and flooding as rising sea levels, stronger storm surges, and increasing wave energy are all intensified by climate change, posing critical risks to vulnerable areas. Conventional engineering solutions, such as seawalls, breakwaters, and groins, while effective in protecting specific areas, often incur high costs and cause environmental impacts, including habitat loss, altered sediment transport, and increased erosion in adjacent areas. Moreover, these solutions lack adaptability to the dynamic and long-term impacts of climate change, leaving a critical need for cost-effective and environmentally friendly alternatives.

This study investigates the potential of buoyant, flexible vegetation as a sustainable solution for wave attenuation by addressing the critical gap in understanding how vegetation buoyancy and flexibility influence wave energy dissipation. An experimental approach is developed to simulate vegetation and evaluate its wave attenuation performance under controlled conditions.

The experiments have been conducted in the wave basin at Queen's Marine Laboratory in Portaferry, Northern Ireland. The 16 m by 18 m basin, equipped with 24 wave paddles generating regular and irregular waves, has been designed to minimize boundary reflection effects using curved transition panels. The basin also features a gravel-covered coastal region and a sloped bottom mimicking the natural environment. Artificial plants, made of a highly flexible low-density polyethylene to minimize stiffness effects, are used to simulate vegetation with varying buoyancy, including fully buoyant, semi-buoyant, and non-buoyant. Wave probes—strategically placed to measure reflection effects and wave attenuation—enabled high-precision analysis of wave-vegetation interactions.

The results demonstrate distinct deformation behaviors, with fully buoyant stems deforming up to 160 mm and showing potential for effective wave attenuation compared to non-buoyant stems. S-shaped patterns are observed under high-frequency waves, while C-shaped patterns have occurred at lower frequencies. These findings highlight the critical role of buoyancy in driving wave attenuation performance, offering data-driven insights into wave-vegetation interactions. These findings provide practical guidance for designing eco-friendly, adaptable coastal defenses, particularly in erosion-prone regions. The collected data will also serve as the foundation for future numerical simulations to further validate and optimize nature-based coastal defense strategies.

Presenting Author: Saeideh Baghanian Queen's University Belfast

Presenting Author Biography: Saeideh Baghanian is a PhD researcher at Queen’s University Belfast, specializing in wave dampening by marine and coastal vegetation. Her research focuses on wave-vegetation interactions, including factors like vegetation flexibility and deformation amplitude, to develop sustainable coastal protection strategies.
With a background in civil and coastal engineering, she has worked on wave-climate interactions under climatic scenarios, as well as projects involving desalination system design, sediment transport analysis, and hydrodynamic simulations for coastal structures. Her current research is funded by QUADRAT, a UK Research and Innovation funding body, in collaboration with the Agri-Food and Biosciences Institute (AFBI).