2 sentences

1. 这条河道淤积严重，需要定期进行人工疏浚。

   zhè tiáo hé​dào yū​jī yán​zhòng, xū​yào dìng​qī jìn​xíng rén​gōng shū​jùn.

   This river channel is heavily silted and requires regular manual dredging.

   Source: Dong Chinese Dictionary

2. 由于泥沙淤积，这条航道已经变得非常狭窄。

   yóu​yú ní​shā yū​jī, zhè tiáo háng​dào yǐ​jīng biàn de fēi​cháng xiá​zhǎi.

   The channel has become very narrow due to siltation.

   Source: Dong Chinese Dictionary