low water vs waning

low water

noun
  • The temporary situation of having little money. 

  • The lowest stage of a river. 

  • The location of low tide in a coastal area. 

waning

noun
  • The fact or act of becoming smaller. 

  • The fact or act of becoming less or less intense or present; fading. 

adj
  • Becoming weaker or smaller. 

  • Of the lunar phase: as it shrinks when viewed from the Earth. 

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