Stage discharge prediction in heterogeneous compound open channel roughness

Prediction of flow discharge in the rivers performs important role in flood management. Using the compound open channel concept, the real condition in natural streams can be accurately estimated. A compound open channel includes a main channel and floodplains that usually floodplains are rougher than the main channel. Several empirical approaches have been proposed for estimating the discharge of flow in the compound open channels. In this study, the accuracy of the empirical approaches including Single Channel Method, Divided Channel Method (DCM), and Coherence Method were assessed to estimate the discharge of flow in heterogeneous compound channel roughness. To this purpose series of experiments were programmed and performed at the hydraulic laboratory of Tehran University. To compare the obtained results with previous studies, 396 data related to discharges of flow in the compound open channel were collected and used for evaluating the performance of applied methods. Results showed that DCM with assuming the virtual perpendicular line as boundry line between sub-sections (main channel and floodplains) with coefficient of determination more than the 0.90 has suitable performance through the empirical approaches and can be used for practical works. © 2016 Indian Society for Hydraulics.