OWC breakwaters are typically installed in coastal areas, where variable bathymetry, such as sandbars and coral reefs, generally exists (Mei in J Fluid Mech 152:315–335, 1985 20). Water wave propagation may be modified significantly due to the presence of variable bathymetry. The evaluation of waves due to the uneven sea bottom is of interest in this community. Physical phenomena such as wave resonance, setup, and breaking may occur while waves are propagating over variable bathymetry. Davies (Dyn Atmos Oceans 6:207–232, 1982 4) derived a linear perturbation solution for the reflection of a monochromatic wave train propagating over periodic sinusoidal ripples. Theoretical results demonstrate that strong wave reflection can be observed when the incident wavelength is twice that of the bar. This phenomenon is physically termed Bragg resonance. Mei (J Fluid Mech 152:315–335, 1985 20) further presented a theoretical illustration of Bragg resonance induced by sandbars.