AbstractA new combinative method of boundary‐type finite elements and boundary solutions is presented to study wave diffraction‐refraction and harbour oscillation problems. The numerical model is based on the mild‐slope equation. The key feature of this method is that the discretized matrix equation can be formulated only by the calculation of a line integral, since the interpolation equation which satisfies the governing equation in each element is used. The numerical solutions are compared with existing analytical, experimental, observed and other numerical results. The present method is shown to be an effective and accurate method for water surface wave pro