Analysis of flow characteristics in a compound channel: comparison between experimental data and 1D numerical simulations

The common configuration of rivers is a main channel flanked by floodplains. During flood events, the main channel is not enough to discharge the flow and floodplains are submerged. The momentum transfer due to the difference of the velocities between the sub-sections generates a complex 3D flow structure. For the study of the influence of this structure in flow modeling, measurements of the velocities in a prismatic compound channel have been made. Seven 1D methods to compute the sub-section and total discharges have been applied. Comparisons between experimental data and modeling reveal good agreement when simple models that indirectly take into account the momentum transfer are applied.