Enhanced Nearshore Wave Characterization Using Nonlinear Pressure Reconstruction: Applications to Wave Attenuation in Vegetated Coastal Zones

 

Accurate nearshore wave measurements are essential for assessing coastal protection and the performance of nature-based solutions in vegetated environments. However, conventional approaches face major limitations in shallow and intertidal zones: wave buoys are ineffective where wave-seabed interactions dominate, while wave gauges require complex infrastructure and are vulnerable to damage. Although remote sensing techniques such as radar, cameras, and lidar have been explored, they remain costly and logistically demanding. Pressure sensors provide a robust and cost-effective alternative, but reconstructing surface wave elevation from bottom pressure measurements is challenging in shallow water due to pronounced nonlinear effects.

Linear pressure transfer methods systematically underestimate wave heights and fail to capture nonlinear extreme events, leading to errors in wave energy estimates and attenuation assessments. These limitations are particularly critical in vegetated coastal zones, where accurate wave characterization underpins evaluations of wave attenuation and coastal protection capacity.

This study implements and validates the nonlinear weakly dispersive pressure reconstruction method of Bonneton et al. (2018) for nearshore wave climate characterization. The method reconstructs surface elevation using first- and second-order time derivatives and frequency-domain filtering, providing improved performance under shallow-water conditions.

Pressure sensor arrays were deployed across seven coastal sites in Northern Ireland, spanning sheltered sea loughs to exposed embayments, with deployments capturing storm events with significant wave heights exceeding 0.5 m. Complementary wave tank experiments were conducted to validate hydrostatic, linear, and nonlinear reconstructions against wave gauge measurements over wave periods of 0.9-1.8 s and wave heights of 20-80 mm.

Results show that nonlinear reconstruction yields wave heights up to 56% higher than linear methods under energetic conditions and agrees within 8.4% of wave gauge measurements. Field observations indicate wave energy dissipation upto 18.5% across vegetated transects. The approach enables robust quantification of wave attenuation and supports the evaluation of coastal nature-based solutions across vegetated shorelines.

References

Bishop, C. T., & Donelan, M. A. (1987). Measuring waves with pressure transducers. Coastal Engineering, 11(4), 309–328.

Bonneton, P., Lannes, D., Martins, K., & Michallet, H. (2018). A nonlinear weakly dispersive method for recovering the elevation of irrotational surface waves from pressure measurements. Coastal Engineering, 138, 1–8.