Steepness and spectrum of nonlinear deformed shallow water wave

The process of the nonlinear deformation of a shallow water wave in a basin of a constant depth is studied. Characteristics of the first breaking of the wave are analyzed in detail. The Fourier spectrum and steepness of the nonlinear wave are calculated. It is shown that the spectral amplitudes can be expressed using the wave front steepness, which allows the practical estimations.