catchment vs coulee

catchment

noun
  • A catchment area, or the people it serves. 

  • Any structure or land feature which catches and holds water; the collection of such water. 

verb
  • To divide into catchment areas. 

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. 

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