عنوان مقاله [English]
Details of a numerical model for predicting free water surface in severe gradient, presents in this paper. In this model, concerning to use non-hydrostatic pressure in seas and rivers for two-dimensional modeling, a new method named step method has been used. In fact this model is conflated of step method and sigma coordinate system. Finally, the results of this model are compared with results of a model with sigma coordinate regarding hydrostatic pressure and water surface profiles and pressures analyze and compare in different times.