Study On Sediment Transport Characteristics Of Sediment Transport Channel In Weishan Irrigation Area Based On Two-dimensional Water And Sediment Model

After the Xiaolangdi Dam was put into operation and run formally,the water and sediment conditions of the lower reaches of the Yellow River region have changed a lot,and some new situations have emerged,such as the decrease of water diversion capacity and the decrease of sediment discharge,especially the Yellow River irrigation area in Shandong Province.Under the new situations of the continuous operation of Xiaolangdi Dam,the problem of sand discharge has not been alleviated,in order to solve the problem of sediment in Weishan irrigation area,improve the runoff and sediment transport capacity of the channel,reduce sediment deposition and ensure the normal operation of the irrigation area,the research object of this paper is The East Soil Transferring Channel,a reconstructed sediment drainage in Weishan Irrigation Area.On the basis of analyzing and summarizing the characteristics of water and sediment of the Soil Transferring Channel in the current year,with the goal of controlling the sedimentation of the sand channel,Mike 21 software was used to build the corresponding two-dimensional hydrodynamic and sediment numerical model to explore the characteristics of sediment transport,and design typical operating conditions to simulate and predict the runoff characteristics and sediment deposition distribution law,and screen the optimal scheme of runoff and sediment transport.This study provides theoretical support for sediment treatment and utilization in the main channel of the Yellow River in Shandong Province and other lower Yellow River irrigation areas.The main contributions and innovation points of the thesis are as follows:(1)Based on the measured runoff and sediment data of the irrigation channel and the hydrological data in previous years,using mathematical statistics method to analyze the characteristics of water and sediment in the current year,the new situation of the water diversion capacity of Weishan Irrigation Area was obtained.In the analysis of water flow characteristics,the flow rate was positively correlated with the water level.In exploring the water level of different flow rates at different sections,it was found that the change law of the cross sections and the water depth along the way.(2)By analyzing the sampling results,the temporal and spatial distribution law of sediment concentration was obtained.In space,the amount of sand decreased along the canal;in time,the amount of sand was positively correlated with water diversion flow rate.Through the analysis of the sediment transport capacity of the channel,it was found that the discharge has a great influence on the sediment transport capacity of the main channel,in order to meet the balance of erosion and deposition,the diversion flow of the East Channel in the irrigation area should be controlled above 40m~3/s.In the analysis of sediment grain size,it was found that the main sediment in the channel composed of clay and silt,and the proportion of sand was very small.The distribution of sediment particle size during summer irrigation period was the largest,followed by autumn irrigation,and spring irrigation was the smallest;spatially,it showed a trend of gradual refinement along the channel.(3)A two-dimensional water flow and sediment transport mathematical model suitable for sediment transport channel was established basing on MIKE 21 software,according to the topographic,hydrological and sediment data of the channel in the current year,the model was calibrated and verified,and the simulation results were compared with actual values,the results of numerical simulation could reflect the actual situation of hydrological and sediment deposition well,the above contents verified the reliability of the planar two-dimensional water flow and sediment model,and could be used for the numerical simulation of sediment erosion and deposition evolution of sediment transport channel.(4)Four working conditions of sediment prediction simulation were set up,and the verified two-dimensional water flow and sediment mathematical model was used to realize the visualization of hydrodynamic and sediment prediction simulation.According to the characteristics of water flow(velocity and water level),the development of sediment longitudinal and transverse form,and the total amount of deposition four perspectives,through theoretical analysis and numerical calculation,the third scheme was determined the optimal scheme that the channel can achieve the balance of erosion and deposition--under the flow rate of 40m~3/s,under the guidance of basic theory of sustainable development,it provided a theoretical basis for the actual regulation and operation of sediment transport channel in irrigation area.