Hybrid nature-based and engineered solutions for wave resonance reduction

Mangroves are widely used for shoreline protection, yet their effectiveness can be limited under resonant wave conditions. Hybrid defenses combining mangroves with submerged breakwaters have therefore been proposed, but certain configurations may unintentionally amplify waves through resonance. This study investigates how mangrove–breakwater configurations influence wave resonance in an idealized coastal basin. The basin’s natural period is obtained analytically from the linearized shallow water equations, and resonance dynamics are simulated using a finite volume numerical model. Numerical results are validated against wave flume experiments, showing strong agreement (N-RMSE < 7 % ) between the two approaches. A systematic parameter study identifies breakwater submergence depth as the primary control on resonance severity, with shallow submergence producing amplification ratios above 5.8. Structural spacing and proximity to reflective boundaries further govern resonant behavior, while friction within mangrove and breakwater regions consistently suppresses amplification. These results clarify the competing roles of reflection, geometry, and dissipation in hybrid coastal defenses and provide guidance for designing configurations that mitigate resonance and enhance shoreline resilience under changing wave climates.