Water surface profiles (WSPs) are among the most valuable information in artificial and natural open channels. Most of the conventional methods for computing the WSPs in compound channels are based on the water surface calculated by the divided channel method (DCM) which is used by HEC-RAS. However, this approach cannot predict the water surface with good accuracy when dealing with compound channels. Therefore a new approach is implemented to calculate the WSP. This approach consists of two steps. In the first step, the rating curve is computed based on the newly proposed method by Maghrebi et al. In the second step, based on the governing equations for gradually varied flow including energy equation, the WSP is computed. The experimental results reported for three sets of measured WSPs in compound channels and WSP measurements of the Main River are used to evaluate the accuracy of the proposed method. The results show that the proposed technique can predict the WSP with better accuracy in comparison to the HEC-RAS and CES models.

Keywords