alluvion

(noun) gradual formation of new land, by recession of the sea or deposit of sediment.

(noun) the rising of a body of water and its overflowing onto normally dry land. Synonyms: flood, inundation, deluge. Example: "Plains fertilized by annual inundations."

(noun) clay or silt or gravel carried by rushing streams and deposited where the stream slows down. Synonyms: alluvial sediment, alluvial deposit, alluvium.