Research On The Transport Of Suspended Sediment And Flow In Area Of Irrigation Ditch Nodes

High efficiency of muddy water in canal irrigation district has always been an important aspect in the study of agricultural water-saving under mode of water-saving irrigation,characteristics of suspended sediment transport in canal system node region is a significant topic of the muddy water resources comprehensive utilization in Yellow River irrigation area.Mainly from the existing researches on lateral lateral canal,focus on the flow characteristics of the structure,the turbulence characteristics of flow,water sediment characteristics,law of sediment deposition,and the size of the re-circulation region scale numerical fitting,etc,and there are certain differences between actual engineering problem solving.Based on the theoretical analysis,numerical simulation and related physical model test data,we will put effort into the characteristics of the scale of the lateral split plane back-flow region,distribution of suspended sediment siltation in node region,the relationship between the suspended sediment grain size distribution in vertical direction,channel sedimentation analysis in local contraction area and the problems of muddy water carrying capacity.The main results are as follows:1.The scale size of the back-flow area is mainly related to the flow rate of the main branch channel.When the flow velocity ratio is larger,the lateral flow characteristics are not obvious;the flow rate is smaller;the back-flow area increases laterally,and the longitudinal range of the back-flow area becomes smaller.When the shunt flow rate is smaller,the flow rate is relatively larger,and the transverse range is smaller along the longitudinal side of the canal.At the same time,there are two extreme situations in the process of flow rate ratio change.Firstly,the branch flow velocity is zero,via the channel is not flowing.Cecum back-flow is formed on the side of the canal.The second,the main flow velocity is zero,and the re-flux area is reduced.Only a small area of symmetrical re-flux region is formed on the side wall of the branch canal,which is common in the case of stagnant lakes water diversion andits water level unchanged.2.Deposition distribution of the lateral canal is a main factors influencing their lateral canal flow capacity.The region flow structure disorders,causing the water carrying capacity reduced and sediment to deposit,and finally forms the bar in front of bronchitis outfall.At the same time,this study points out that the main factor of the lateral canal flow capacity must distinguish the water level and the silting of the bar at the entrance area,in addition to the lateral canal's own conditions.The comprehensive results of the both actually could reduce the effective water level,and the flow ability of lateral canal is abate,causing subsequent series of sediment deposition problem.Among them,the obvious influences in the process of suspended sediment deposition are studied in different levels of channel cohesion and local contraction region,including sedimentation topography,sedimentation development,and high water level,and so on.3.For the suspended load particle in vertical distribution,The critical particle size of water depth suspended could be deduced.Then,make sure clearly the coarse and fine particles and secondary particles along the vertical distribution range and distribution characteristics.Ross formula respectively was applied to a single particle group and the total load,and graded vertical relations could be available by the two type division.Considering the characteristics of particle distribution form,different water depths of sediment concentration and grain size distribution relations were obtained.4.Carrying-capacity of sediment under condition of muddy water,with change of sediment concentration,shows the ability of the double value relations.The root cause is the difference in viscosity and density between muddy water and water.Judging from the difference of sediment concentration in the critical scour and deposition background,the paper discusses the existence of the "zonal" distribution relationship of the water carrying capacity and the upper and lower limit of the capacity of carrying capacity.The relationship between the upper and the lower bound is a reflection of the degree of deviation from equilibrium.