billabong vs winterbourne

billabong

noun
  • An anabranch, backwater or oxbow lake that is temporarily cut off from the main river, especially one that is only filled with water during the rainy season and can sometimes dry up completely. 

winterbourne

noun
  • A stream that only flows in winter or after wet weather, particularly in an area rich in limestone. 

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