Hydraulic analysis of compound open channel

Distribution of velocity of flow in compound open channel due to interaction of floodplains and main channel is strongly non-uniform. Defining the distribution of flow velocity is an important factor in calculation of sediment transport and estimation of flow discharge. One of the correction factors in calculation of flow discharge and shear stress are momentum( 𝛽) and energy (𝛼) coefficients. In this study, the effect of 𝛽 and 𝛼 coefficients on Froude number and specific energy are assessed. Stage-discharge relationship in compound open channel was assessed using some empirical formula including Single-Channel Method (SCM), Divided-Channel Method (DCM), and modified divided-channel method (MDCM) and compared with together. When the discharge only flows in main channel all the empirical has a same result whereas by increasing the discharge and covering the floodplains by flow the results of them are different. The highest value of outcome of empirical formula is related to the SCM. Results indicated that considering the energy and momentum coefficients have significant effect on distribution of Froude number and specific energy.