Using a split operator approach and characteristic method

the depth averaged two dimensional (2D) flow equations are transformed into a series of one dimensional(1D) equations which are solved by a characteristic finite difference scheme. A boundary library containing 28 different types of boundaries is constructed on a rectangular grid to include any possible boundaries which may appear partly or simultaneously in real water fields. The formulae for calculations of interior nodes and boundaries are given. The boundary conditions and other input data required for modeling are designed as lookup tables.