比如，几个世纪以来，尼罗河、底格里斯河和幼发拉底河每年的洪水给下游山谷的居民带来了肥沃的淤泥和水源。

For centuries, the annual floods of the Nile, Tigris, and Euphrates, for example, have brought fertile silts and water to the inhabitants of their lower valleys.

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进行挖泥工程时，只可使用密封抓斗式的机械挖泥机，以挖掘河床或塘底的淤泥。

For dredging works, only mechanical dredgers with bucket-type closed-grabs shall be used for the dredging of river bed or ponds.

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