Two-dimensional flood plain flow. I: Model description

Development of a new two-dimensional flood plain flow model, Hydro2de, is described. A finite volume approach is presented that ensures a nonoscillatory solution for flow conditions present on flood plains. The treatment of variable bed topography, friction losses including vegetation, and the boundaries between wet and dry cells are explained in detail. Tests are made to check conservation of mass for flows in the presence of initially dry domains. Numerical errors for flows diagonally across the calculation grid are analysed and a correction to reduce these errors is proposed. Part II outlines the performance of the model for two floods on the Waihao River flood plain.