Shallow Water Wave

A shallow-water wave is a surface gravity wave in water shallower than about one-twentieth of its wavelength (depth-to-wavelength ratio below 0.05), where the wave feels the bottom across the full water column. Its phase speed depends only on depth, c = sqrt(g*h), so it is non-dispersive: all wavelengths travel at the same speed for a given depth. As waves shoal toward shore the speed and wavelength shrink while period stays fixed, which steepens and refracts them and leads to breaking. Tides and tsunamis behave as shallow-water waves everywhere because their wavelengths far exceed ocean depth.