Author(s): Xihang Xu; J.J. O'Sullivan; Md Salauddin
Linked Author(s): John D. OSullivan, Md Salauddin
Keywords: No Keywords
Abstract: Traditional sea defences, including seawalls and breakwaters, are facing escalating pressure from climate change and sea-level rise and are becoming ecologically and economically unsustainable. Hybrid coastal defences that combine natural features with engineered structures offer a promising alternative, but their hydrodynamic performance remains poorly understood. In particular, placing artificial reefs near seagrass canopies may both support seagrass growth and improve wave attenuation. This study investigates the combined wave-attenuation effects of artificial reefs and seagrass through laboratory experiments under irregular wave conditions, using seagrass mimics that closely mimic natural vegetation. Results show that the presence of seagrass reduces wave transmission by an additional 8.6% compared with reefs alone. An equivalent height enhancement index is introduced to translate this benefit into engineering terms, indicating that seagrass can provide wave attenuation equivalent to increasing reef height by up to 39%. The findings of this study provide a practical design tool for coastal engineers developing sustainable hybrid coastal defence systems.
Year: 2026