Long-term predictive morphological models are essential for planning and management of coastlines. However, to have widespread applicability such models must be computationally efficient. To achieve this aim, an approximate method was developed to depict the non-linear wave parameters as a wave is propagated across the nearshore zone, where the wave is considered to be transformed by the processes of shoaling, refraction and breaking. Non-linear approximations for the parameters of wave height, wave length, wave orbital velocities and velocity moments are described by this method and the results compared primarily with experimental data from both planar beaches and barred profiles. The results of this validation exercise demonstrated that the new method can adequately describe the relevant non-linear wave parameters. Nonetheless, in order to achieve an undemanding approach, the proposed method involved the use of specially defined constants that are fitted empirically. The sensitivity of the approximate wave parameters to these empirical constants are also investigated and discussed.