couloir vs donga

couloir

noun
  • A corridor or passage. 

  • A steep gorge along a mountainside. 

donga

noun
  • A transportable building with single rooms, often used on remote work sites or as tourist accommodation. 

  • A usually dry, eroded watercourse running only in times of heavy rain. 

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