Estimation of discharge in compound channels based on energy concept

A new model is developed to estimate the discharge capacity in straight, symmetric, compound open channels based on the energy concept. The energy loss and the transition mechanism in these channels are analysed based on mechanical analysis, in which the momentum transfer mechanism is taken into account as a product of the apparent shear stress. Four representative formulae of apparent shear stress are selected to validate the present model; the results indicate that the performance of the present model depends on our ability to accurately predict the apparent shear stress. The comparisons with experimental data indicate that the most appropriate apparent shear stress formula is that of Moreta and Martín-Vide; however, for the compound channels without roughness differences between the main channel and floodplains, Christodoulou's formula is still recommended for its simplicity. Comparisons with other models indicate that the present models are simple in manipulation and have a reasonable accuracy for engineering purposes.

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