Study On A Numerical River Bed Evolution Model Of Sangri Section In Yarlung Zangbo River

In recent years,with the implement of national Western Development strategy,The communication between the Qinghai-Tibet Plateau region and the whole country is becoming more and more close.Along with the development of the Qinghai-Tibet Plateau,it's necessary to speed up the development and utilization of the Yarlung Zangbo River.However for the lack of the data of riverbed evolution research in The Yarlung Zangbo River,the development and utilization of the it is restricted.So it's of great significance to study the river bed evolution in the Yarlung Zangbo River.It will also provide a reference for the Yarlung Zangbo River's study in the future.The section of Sangri is selected to study the river bed evolution in the Yarlung Zangbo River.The 3D water and sediment of uncoupling mathematical model is established through EFDC to study the river bed evolution in Sangri River.(1)Using the measured data,the change of the river cross-section is analyzed to discuss the recent riverbed evolution theory in Sangri section in Yarlung Zangbo River;The riverbed changes rapidly in the upper reach;in the middle and lower reaches the river regime is relatively stable.(2)Introduce the process of establishing mathematical model,control equation of the discrete solution,and all parameters needed in the process of the equation set.(3)The 3D hydrodynamic model is established,and the model of flood flow condition under different frequency is calculated.The results show that the velocity and the slope of upper reach are smaller;The velocity and the slope of middle section are bigger,it is not easy for sediment to settle down in this section;in the downstream of the river,velocity and talweg goes down quickly,and the sediment transport from upstream will settle down.(4)The 3D mathematical model of water and sediment is established,and the transport of the suspended load and bed load is analyzed separately under different flow conditions,the transport theory of suspended load and the distribution of bed load is regained;then the riverbed evolution for a long period of time is simulated to obtain the long-term forecast in riverbed evolution of Sangri section.It shows that,in the middle and lower reaches,the riverbed is deposited;in the middle sharp bend,the riverbed has a big change in deposition and erosion.