Hybrid Green–Grey Infrastructure for Wave Attenuation

Time: 9:30, Tuesday, September 29, 2026

Venue: Room 301,  A5 Building, Institute of Mathematics-VAST

Abstract:Mangroves are widely recognized as a nature-based solution for coastal protection due to their ability to attenuate waves, reduce hydrodynamic energy, and contribute to shoreline stability. However, the effectiveness of mangrove forests strongly depends on their maturity and physical characteristics. During the early stages of restoration, young mangroves have relatively small stems, limited root systems, and low vegetation density, making them particularly vulnerable to incoming waves and often unable to provide sufficient coastal protection. This limitation creates a critical period in which additional protection is required to support both wave attenuation and successful mangrove establishment.
This study investigates a hybrid green–grey coastal protection strategy in which young mangroves are complemented by permeable engineered structures. A mathematical model based on the shallow water equations is developed to simulate wave propagation through the combined system. Mangrove resistance is represented through vegetation-induced drag, while the grey component is incorporated as a permeable structure that reduces incoming wave energy while allowing water exchange. Different configurations are investigated to examine how the characteristics and placement of the supporting structure influence wave conditions within and around the mangrove zone.
The results demonstrate the potential of the grey component to reduce wave exposure during the vulnerable early stages of mangrove development, while the vegetation progressively contributes greater wave attenuation as it grows and becomes denser. This complementary mechanism provides a pathway toward coastal protection in which engineered structures support, rather than replace, natural protection. The proposed framework highlights the importance of considering mangrove growth stages in the design of hybrid coastal infrastructure and provides a basis for developing adaptive protection strategies that transition progressively from structural support toward predominantly nature-based coastal defence.