| 摘 要： | Aggradation of channel on the lower reaches of the Yellow River is mainly governed by the regimen of river discharge and sediment delivered from upstream. In the long run, channel accretion exhibits alternate increase and decrease, somewhat periodic in nature.The long-term average annual deposition is something like 300 million tons. Besides the aforesaid factor affecting scouring and depositing along the river channel along the lower reaches, there are also the following factors of influence: fluvial processes and changes in river bed in previous stages, operation of Sanmenxia Reservoir in regulating floodwater and sediment delivery, as well as conditions at the river mouth. After undergoing 3 consecutive periods of accretion-degradation-accretion, and being subjected to different measures to cope with the problem at different times, adapting to the actual condition, there is now only accretion to limited extent above Jiahetan and .below Aishan, most of the deposits being laid in the intermedite section. The distribution of the deposits in the crosswise direction is related to overflowing onto the floodplains, the duration, and the condition of levees there (to protect the farmland on the floodplains from ordinary floods). During the period from 1950 to 1983, a total of about 5 biIlion tons of sediment deposited on the floodplains on the lower reaches, comprising 70% of the entire volume of deposition, distributed unevenly though, mainly outside the area sheltered by the levees, effecting in an increase in transverse slope of the channel. In some sections, "suspended river" was formed within the already "suspended" river (river bed lying above the land surface behind the dykes).Sequence of years of observation in the fifties was chosen and the regulating effect of the Longyangxia, Liujiaxia and Sanmenxia and other reservoirs is also taken into account. In the 12 years from 1984 to 1995, average annual runoff on the lower reaches of the Yellow River will be 38.8 billion m~3, carrying 1.61 billion tons of sediment each year. Through comprehensive analysis of the observed data, it has been found that the avergae yearly deposition on the lower reaches of the Yellow River will be something like 400 million tons for the same period, mostly in the reaches between Jiahetan and Aishan. Channel accretion in the reaches from Aishan to Lijin will be somewhat on the ascent.
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