catchment area vs clough

catchment area

noun
  • An area from which water drains into a particular lake, river, etc.; the catchment area of a large river includes its tributaries. 

  • The area served by a local institution, such as a hospital or school, or by extension, a railway station. 

clough

noun
  • A sluice used in returning water to a channel after depositing its sediment on the flooded land. 

  • A narrow valley; a cleft in a hillside; a ravine, glen, or gorge. 

  • The cleft or fork of a tree; crotch. 

  • A wood; weald. 

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