Development Of Mathematical Model For Unsteady Sediment Transport Of The Lower Weihe River

It is one of the important tasks of the Yellow River management that to decrease the sediment siltation in the lower Weihe river by changing the operation modes of the Sanmenxia project and reducing the TongGuan evaluation. After the reduction of the TongGuan evaluation whether scouring or depositing will act on the riverway in the lower Weihe river is directly relative to significant decisions such as synthetical management programming. This paper develops a mathematical model for unsteady sediment transport of the lower Weihe river to provide a tool to research the scouring and depositing process in the lower Weihe riverway conveniently after the reduction of the TongGuan evaluation, which is based on the characteristics of the lower Weihe river.This paper presents the mathematical model for unsteady sediment flow of the lower Weihe river by summarizing the advantages and shortcomings of the existing sediment mathematical model in view of the sedimentation engineering problems. Considering flood lank and river channel characteristics of the fluvial river, the area of flow is dealt by flood lank and river channel independently. By using the Preissmann weighed implicit 4-point scheme the mathematic model basis equations is dispersed. In hydraulic calculation thispaper provides the difference numerical solution of the St.Venant equations and discusses the calculation methods of the coefficients in the difference equations, then offers the coefficients calculation methods. In sediment calculation this paper offers sediment calculation equations of every sediment groups so as to considering the inter-impact of different sediment groups. Because of the application of the Preissmann implicit scheme, it makes the mathematical model can calculate the flood routing and channel deformation of the nature channel with long distance. The developed model has been programmed. The model is calibrated by using of the measured data on the reach between Lintong and Huayin of Weihe river from September to October in 1983. The computed water levels and discharges agree with the measured ones. The computed results are reasonable.