Quasi-two dimensional mathematical model for prediction of flow discharge over ompound sharp-crested weirs

Water measurements play a pivotal role in the irrigation and drainage networks. Due to effective limitations of simple sharp crested weirs, compound sharp crested weirs have attracted the attention of scientists and civil engineers recently. With this kind of weirs, flow discharge is measured with a reasonable sensitivity over a wide flow range. In this paper, by assumption of flow similarity between compound sharp crested weirs and compound open channels, a new method based on numerical solution of a quasi-two-dimensional mathematical model has been proposed for discharge calculation of compound weir. The numerical results were compared with the experimental data of Jan et al. (2006) and the traditional method (theoretical equations of simple weirs). These comparisons revealed that the proposed method had nearly 1 percent error while the traditional method had more than 8 percent error.