intertidal zone vs riverside

intertidal zone

noun
  • The part of a shore between high water and low water, especially the beach exposed at maximum ebb spring tides. 

riverside

noun
  • A bank or side of a river. 

adj
  • At or near the side of a river. 

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