Abstract: With the aim of better understand and parameterize the physical processes involved in flow-mangrove interaction, wave attenuation and drag forces along a 1:6 scale fringe Rhizophora mangrove forest are studied experimentally. The 26?m long forest is composed by 135 models built reproducing mature Rhizophora mangrove trees with 24 prop roots. Hydrodynamic conditions are scaled using Froude similarity based on values collected in nature. Regular and random waves are tested and three water depths are considered to account for the influence of variable mangroves frontal area along the vertical. Wave decay analysis highlights the importance of considering the effect of flume bottom and walls friction. Neglecting this additional damping can result in a high overestimation of the mangrove dissipation capacity. It is proven that water depth, and the associated mangroves frontal area, and wave height are the dominant variables driving wave attenuation for short waves. The slope seaward the forest induces wave shoaling leading to an increase of wave steepness. Accordingly, the exerted forces on the mangroves also increase along the first 3?4?m of the forest. Smaller forces are recorded further into the forest where wave decay formulations fit well to the recorded wave heights. In general, analytical drag forces obtained by using mangrove trees induced damping coefficients compare well to the forces measured within the forest. However, analytical drag forces can lead to overestimations of up to double in some cases. This aspect is very important when experimental results are used to feed numerical or analytical models based on the introduction of a drag force in the momentum equation. These models should be calibrated using, whenever possible, direct force measurements.

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