catchment vs wellspring

catchment

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

  • A catchment area, or the people it serves. 

verb
  • To divide into catchment areas. 

wellspring

noun
  • The source of water for a stream, spring or well; a fountainhead; a wellhead. 

  • A perennial source of anything; a fountainhead of supply or emanation; resource. 

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