An Improved Approach for Flow Prediction in Compound Open Channel Flowof Uniform Roughness

Abstract

Most natural rivers consist of a main channel and the adjacent floodplains. The various subdivision methods fail to determine the discharge capacity in rivers with overbank flow because of the ignorance of the strong interaction between the main channel and the shallow floodplains. An experimental investigation is performed to study the effect of momentum transfer in terms of an apparent shear stress in rough and smooth compound channels for different hydraulic, geometric conditions and roughness ratios. A new method to calculate flow in compound channels is proposed. The approach is based on a new model on the momentum transfer coefficient at the vertical interface and the horizontal interface between adjacent flow compartments, typically between the main channel and floodplain of a two-stage channel. The new approach is found to give better results as compared to the other approaches when applied to the present experimental data sets, large channel of FCF data sets and some natural river data sets.