alluvion vs mishap

alluvion

noun
  • The increase in the area of land due to the deposition of sediment (alluvium) by a river. 

mishap

noun
  • An accident, mistake, or problem. 

  • Evil accident; ill luck; misfortune; mischance. 

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