Prediction of Sediment Transport Capacity in Rivers Using Quasi Two-Dimensional Mathematical Model

Sediment rating curve is an essential factor for many river engineering subjects and computations such as dredging, design of storage dams, river intakes design and sand mining management. Although, this curve is established using simultaneous measurement of flow and sediment transport discharges, however, due to lack of reliable data during flood events, it has limited reliability in flood conditions. This limitation may be coped with using a simple and practical tool like a semi two dimensional mathematical model. As an efficient and practical solution, these kinds of models currently have widespread applications in hydraulics of flow and sediment transport subjects. In this study, using the semi 2-D mathematical model of Shiono and Knight, the transverse distribution of flow velocities were computed and then with combining these results with some empirical sediment transport formulas, the lateral profiles of sediment transport and total sediment discharges were predicted across Gharesoo river at the SiahAb station. The results indicated the suitable capability of Shiono and Knight model in computation of lateral distribution of flow velocity with about mean error of 8.7 percent. Also, among the selected sediment transport formulas, the Engelund-Hansen (1967) equation with mean error of 34 percent had a highest accuracy in prediction of river sediment transport discharges and sediment rating curve. The Yang (1996) and Ackers-White (1973) equations with mean errors of 48 and 64 percent, respectively attained the second and third places. Laursen equation with mean error of 258% corresponds to very low accuracy.