catchment vs inland sea

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. 

inland sea

noun
  • A large but relatively shallow expanse of water within a landmass, sometimes connected to the ocean. 

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