Mathematical modeling of flow discharge over compound sharp-crested weirs

Water measurements play a pivotal role in hydraulic and environmental management of river systems, irrigation and drainage networks, and sewer conduits. Due to effective limitations of simple sharp crested weirs, recently compound sharp crested weirs have attracted great attention of civil engineers. With this type of weir, flow discharge is measured with a reasonable sensitivity over a wide range of flow rates. In this paper, the Shiono and Knight (SKM) quasi 2-D mathematical model has been numerically solved for discharge prediction of compound weirs, based on the assumption of flow similarity between compound sharp crested weirs and compound open channels. The modeled results are compared with the experimental data and the conventional method (linear combination of theoretical equations of simple weirs). The comparisons revealed that the proposed method shows improved discharge calculation within 3.8 percent absolute mean error while the traditional method has more than 12.5 percent error.