coulee vs outflow

coulee

noun
  • A stream. 

  • A lava flow. 

  • A deep gulch or ravine, frequently dry in summer. 

  • A reach of water in a bayou that is like a slough but deeper. 

outflow

noun
  • A fluid that flows out. 

  • Any outward movement. 

  • Something that flows out of a sewage treatment plant. 

  • The process of flowing out. 

  • A stream of gaseous material emanating from an active galactic nucleus. 

  • The part of a system that allows material to flow out. 

verb
  • To flow outward. 

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