The study of sediment transport and the changes of river bed using Gstars3 Mathematical model (Case study: GavehRoud River)

The study of sediments behavior and its impact on morphological changes of river and its hydraulics is highly important. Also، In order to explore sedimentation in reservoirs of dams the process of sediment transport in river must be studied. Since using mathematical models based on equations governing on the phenomenon of sediments transport and distribution is one of the suitable methods، in present study sediment transport in a certain part of GavehRoud River was simulated by using Gstars3 mathematical model. By applying the concept of stream tube، this model is able to simulate and predict changes of river bed in both longitudinal and transverse directions. The purpose of this study is choosing a suitable mathematical model for estimating sediment transport rate، such that the simulation with required accuracy in the river is possible. By using this mathematical model، the annual sediments were estimated 620،000 m3. The comparison between the results obtained from simulation and observed rates indicated that Young’s sediment transport function (1979) is the best equation for simulating sediments transport and it has a good correspondence with the conditions of river. At the end، the sensitivity of model to the change of parameters affecting the phenomenon of sediments transport and their impacts on the volume of sediments and longitudinal profile of river were measured. The results indicated that this model has the highest sensitivity toward the changes of sediments transport function.