Introduction to the Yellow River:
The Yellow River in China is famous for its rich sediment. Ancient books in China recorded that "the Yellow River fights for water, and mud ranks seventh". According to the analysis of modern measured data, the average annual sediment transport in the main stream of the Yellow River is 65.438+0.6 billion tons, and the sediment concentration is 35 kg/m3. The Yellow River has the highest sediment concentration in the world.
Since 1970s, due to the progress of soil and water conservation, the amount of incoming sediment has a decreasing trend. About 70% of the Yellow River Basin is the Loess Plateau, and its surface is covered with tens to hundreds of meters of loess. Loose soil, low erosion resistance, easy to collapse when it meets water. Although the annual precipitation in the Loess Plateau is only 400 ~ 500mm, the rainfall is concentrated and the rainstorm intensity is high. Geological and climatic characteristics have caused serious soil erosion, which is the root of sediment in the Yellow River.
The sediment of the Yellow River is not only deposited on the downstream riverbed, but also on the Ningmeng reach of the middle reaches of the Yellow River. Ordos Plateau in Ningmeng reach is a rainstorm-prone area in the middle reaches of the Yellow River. Every rainy season, it often rains heavily here, and floods directly rush into the Yellow River with a large amount of sediment, silting up the riverbed, forcing the main stream of the Yellow River to move northward, directly threatening baotou-lanzhou railway and highways, and doing great harm.
Distribution area of sediments:
According to the amount of incoming sediment and the thickness of sediment particles, the sediment source is divided into three areas: 1, the source area of coarse sediment and heavy sediment, that is, the interval from Hekou Town to Longmen, Malian River and Beiluo River; 2. The source areas of sandy and fine sediment include the main tributaries of Jinghe River, the upper reaches of Weihe River and Fenhe River, except Ma Lian River. In areas with less sediment, above Hekou Town, the tributaries are Nanshan River, Luo Yi River and Qinhe River.