Variation of the dimensionless relative wave celerity as a function of dimensionless wavenumber in the range 0.01-1000; curve parameter is Froude number in the range 0.1-10. [ To the left the celerity is asymptotic to the relative kinematic wave celerity (Seddon celerity: 0.5, for Chezy friction in hydraulically wide channel). To the right, the celerity is asymptotic to the relative dynamic wave celerity (Lagrange celerity: 1/ Fr). For each curve, the point of inflection in the middle corresponds with maximum wave attenuation. Wave attenuation is minimized at both extremes of the dimensionless wavenumber spectra. ]