canal vs river basin

canal

noun
  • An artificial waterway or artificially improved river used for travel, shipping, or irrigation. 

  • A tubular channel within the body. 

  • One of the faint, hazy markings resembling straight lines on early telescopic images of the surface of Mars. 

verb
  • To dig an artificial waterway in or to (a place), especially for drainage 

  • To travel along a canal by boat 

river basin

noun
  • An extent of land where water from rain or snow melt drains downhill into a river or series of rivers. 

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