alluvial vs fluvial

alluvial

adj
  • Pertaining to the soil deposited by a stream. 

noun
  • A deposition of sediment over a long period of time by a river; an alluvial layer. 

  • Alluvial soil; specifically, in Australia, gold-bearing alluvial soil. 

fluvial

adj
  • Of, pertaining to, inhabiting, or produced by the action of a river or stream. 

How often have the words alluvial and fluvial occurred in a corpus of books? (source: Google Ngram Viewer )