Merriam-Webster Collegiate Dictionary - alluvion

 noun  Etymology: Latin ~-, alluvio, from alluere to flow past, deposit (of water), from ad- + lavere to wash — more at lye  Date: 1536  1. the wash or flow of water against a shore  2. flood, inundation  3. alluvium  4. an accession to land by the gradual addition of matter (as by deposit of alluvium) that then belongs to the owner of the land to which it is added; also the land so added