Combined refraction and diffraction models for sea waves over complicated topography and with currents in shallow water

Combined refraction and diffraction models in the form of linear parabolic approximation are derived through smallparameter method.More strictly theoretical basis and more accuracy in the models than Lozano's (1980) are obtained.Some theoretical defects in Liu's model (1985) with consideration of current are not only found but also eliminated.More strict and accurate models are, therefore, presented in this paper.
The calculation results and analysis in applying the models to actual wave field with consideration of bottom friction will be given in the following paper.