influent vs watercourse

influent

noun

  • Fluids flowing in. 

  • A stream which flows into another stream or a lake. 

  • An organism having an important effect on a plant or animal community. 

adj

  • Flowing in. 

  • Exercising astral influence. 

  • Having an important effect on a plant or animal community. 

watercourse

noun

  • Any channel, either natural or artificial, through which water flows. 

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