GRADUALLY VARIED FLOOD FLOW COMPUTATION MODELLING

Abstract

The proposed model was established to simulate the propagation of gradually varied flood flow in deltas. The model incorporates two flow models: a one-dimensi for the river network and a two-dimensional flow model for the flood plain. The combination of the two models was carried out through the exchange of flow between the river and the adjacent flood plain subareas. The momentum equation was approximated by a diffusion model; in which only two terms representing the water surface slope and the friction slope are considered. The implicit Preissmann scheme was utilized to discretize of the governing equations in an alternate grid. This results in a nonlinear system of equations and the unknowns are the representative water surface in each flood plain subareas. The resulting equations was solved iteratively using the Wood Charles method. The flood plain subareas whether inundated or not will be treated after each time step. The velocity field after each time step can be smoothed or not.