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黄河下游是世界上含沙量最多的一段河流,黄河下游的河道成为地上的悬河。目前悬河长度达700余公里,是世界河流中绝无仅有的。由于河水中含大量泥沙,水少沙多,水沙并流,水流的变化率大,这导致泥沙的输送极不稳定,主流河道摆动无常,河道和滩地地形复杂,洪水来势变化极为复杂,并对大堤威胁极大。黄河下游在历史上经常决口,甚至改道,造成严重灾害。据历史记载,黄河下游有过26次改道。本世纪上半叶的50年,黄河下游地区几乎三年两决口,灾害十分严重。新中国成立以后,情况大为改观。从1949年以来的50年中,在黄河中上游的干流上建成和在建在大型水利枢纽十几座,在下游多次加固临黄大堤,并组织了军民联防抗洪抢险,取得了伏秋大汛没有大决口的伟大成就。
The lower Yellow River is the world’s largest section of the river sediment, the lower reaches of the Yellow River into the hanging river. Currently hanging river length of 700 kilometers, is unique in the world’s rivers. Due to the large amount of sediment, less water and less sand, the flow of water and cocurrent, and the large rate of change of water flow, the transport of sediment is extremely unstable. The mainstream of the river is unstable, the terrain of rivers and beaches is complex, and the flood situation is extremely complicated. , And the great threat to the embankment. The lower reaches of the Yellow River often burst their mouths in history and even diverted traffic to cause serious disasters. According to historical records, there have been 26 diversions in the lower reaches of the Yellow River. In the 50 years of the first half of this century, the disaster in the lower reaches of the Yellow River scarcely occurred in almost three years and two. After the founding of New China, the situation has greatly changed. In the 50 years since 1949, over a dozen of large-scale water conservancy hubs have been built and built in the mainstream of the middle and upper reaches of the Yellow River. The Yellow River embankment has been reinforced several times in the lower reaches of the Yellow River. There is no big breakthrough in the flood of great achievements.