landflood vs seepage

landflood

noun
  • An overflowing of land by river; an inundation or freshet. 

seepage

noun
  • Water that has seeped or oozed through a porous soil. 

  • The process by which something, especially a liquid, leaks through a porous substance; the process of seeping. (Also used figuratively: the process of diffusing.) 

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