silt
/sɪlt; sɪlt/ n[U]
sand, mud, etc carried by flowing water and left at the mouth of a river, in a harbour, etc （由流水带到河口、 港口等的）淤沙、 淤泥等. silt, v (phr v) silt (sth) up (cause sth to) become blocked with silt （使某物）为淤泥堵塞
The harbour has silted up. 这港口已被淤泥堵塞.
The sand has silted up the mouth of the river. 泥沙已把河口堵住了.