This is a jukugo word and it uses the on'yomi for both kanji. This on'yomi for 砂 is a bit less common, and you haven't learnt it yet, so here's a mnemnonic to help you:
If there's too much sediment, you need to speak to a shaman (しゃ) about it. Only a shaman has the power to get rid of all that earth and sand and get the river flowing again.
There's a lot of sediment in the riverbed.
Due to the tsunami, a large amount of earth and sand flowed into the second-floor classroom.
After an earthquake there's a danger of landslides.