flowage vs inundation

flowage

noun
  • A flowing or overflowing of liquid. 

inundation

noun
  • The act of inundating; an overflow; a flood; a rising and spreading of water over grounds. 

  • The state of being inundated; flooding 

  • An overflowing or superfluous abundance; a flood; a great influx 

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