rivulet vs waterway

rivulet

noun
  • A small brook or stream; a streamlet; a gill. 

  • Perizoma affinitatum, a geometrid moth. 

waterway

noun
  • A body of water, such as a river, channel or canal, that is navigable. 

  • A conduit or watercourse, such as on the deck of a ship, to drain water. 

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