In the lower reaches, where the current slows, the natural accumulation of sediment in the riverbed has caused the river to change course often in the past.

在河流下游，由于流速变缓，泥沙(等沉淀物)自然而然地堆积在河床中，曾经造成黄河经常改道。

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Later it declined due to the change of a river course.

后来因为河水改道，才逐渐衰落下来。

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It takes a huge effort, backed by a lot of money, to change the course of the mighty river that is the federal government.

FORBES: There's Much Too Little Money In Politics