Paper on mangrove-induced resistance to water waves and its parameterization

Program-Specific Assistant Prof. Che-Wei CHANG and Prof. Nobuhito MORI of the Disaster Prevention Research Institute (DPRI), Kyoto University, in collaboration with the Port and Airport Research Institute (PARI) and Tohoku Gakuin University, used 3D-printed models to replicate the complex root structure of mangroves, studied mangrove-induced resistance and parameterized mangrove effects on ocean waves by laboratory experiments. The study was published online in the international academic journal “Journal of Geophysical Research: Oceans” on June 8, 2022.

 

 

 

Climate change and sea-level rise pose greater challenges to worldwide coastal communities, urging more efficient strategies to mitigate natural hazards and enhance coastal resilience. Green infrastructure/Eco-DRR (Ecosystem-based Disaster Risk Reduction)/Nature-based solution (NBS), which utilizes ecosystems to provide an eco-friendly approach to coastal protection and climate change mitigation, has been gaining attention in recent years. Specifically, mangrove forests are the major type of nature-based infrastructure in the tropics and subtropics. Mangroves, featured by the special root system, are well-known for their resistance against ocean waves and coastal disasters. To quantify mangrove effects on wave attenuation, we need to properly parameterize mangrove-induced resistance, which relies on a better understanding of wave-mangrove interactions.

 

 

 

This study used 3D-printed models to replicate a mature mangrove, the first time in literature to the best of our knowledge, to study wave-mangrove interactions in model-scale experiments. We directly measured fluid velocity and wave forces on mangrove models in different wave conditions. Based on the measurements, we proposed empirical relationships of force coefficients to parameterize mangrove effects which could be used in numerical simulation. Additionally, we observed that as waves propagate through mangroves, the irregularly-shaped mangrove roots caused the fluctuation of fluid velocity and the enhancement of turbulent kinetic energy. Please refer to the published paper for more details.