Nearshore Wave Propagation
Infragravity waves, generated by nearshore wave-wave interaction, potentially increase the coastal hazard. To understand the characteristic of infragravity waves, we conducted UAV-based observations of cross-shore variations of wave spectral characteristics over a barred beach, and confirmed development of low-frequency components by wave-wave interaction between wind-wave and swell components, with bispectrum analysis. We also applied numerical simulations using 1D Boussinesq-type equation to analyze the energy transfer through nearshore non-linear interaction. Observed infragravity wave development was reproduced well, and the model results suggested strong wave-wave interaction between each wave component, including 3rd order non-linear interaction above the sand bar.