Research on the dynamics of the uplift and transport characteristics of sediment in the Lower Yellow River Channel

In this paper, the dynamics of the uplift and transport characteristics of sediment in the river channel of the Lower Yellow River (LYR) are investigated on the basis of previous studies using a large amount of hydro-logical data. An uplift flow velocity formula with a clear conception and suitable for the LYR is chosen based on the grain size distribution data. For the fine sediment, the four candidate formulas (derived by Sha Yuqing, Dou Guoren, Zhang Luohao, and Luo Shiqi) are all applicable to the Yellow River. For coarse sediment, the formu-las derived respectively by Zhang Luohao and Luo Shiqi are more suitable than the other two. The uplift character-istics of sediment in the LYR are investigated based on the formula derived by Zhang Luohao, which indicates that coarse sediment uplift also occurs in the channel of LYR under the moderate flood condition. Then, the Hua-yuankou station, the Gaocun station, and the Lijin station in the LYR are selected as the representative hydrolog-ical stations. The diagrams of the flow discharge versus the ratio of sediment in suspended status are plotted re-spectively based on the measured data lower than the bankfull discharge in the flood season of the three stations. The results show that the sediment transport characteristics of the three stations are similar after introducing the concept of uplift critical flow discharge. Furthermore, by analyzing the sediment transport characteristics of each station, the relationship between the sediment particle size and the factors related to the probability of the suspen-ded movement, i.e., the uplift critical flow discharge, uplift probability coefficient, and the sediment transport index is given, based on which the equation between the ratio of sediment in suspended status and the flow-sedi-ment factors is finally established. With the proposed equation, it shows that the coarse particles in the composi-tion of suspended sediment can still maintain the suspended status as long as the daily average discharge of the LYR exceeds 971 m3/s (obtained from the required discharge to match the predicted reduction of annual average sediment transport in the next 30 years), which indicates that increasing the discharge is an effective approach to directly enhance the sediment transport capacity of the LYR. © 2022 China Water Power Press. All rights reserved.