is the grape river a real river?

Answer 1

I googled "Grape River" with disappointing results, so I went to advanced search and asked for exact matches only. The following list is a few that I found, and there are plenty more. So the answer to your question is, Yes, there is a Grape River. BUT I don't know what your reference is from, so ...

[1] The Travels of Marco Polo — Volume 2 eBook
The river that flows down from Shan-si by Cheng-ting-fu is called “Putu-ho, or the Grape River.”

[2] THE MASSANUTTENS
"George Washington surveyed Fort Valley for Lord Fairfax in 1748, beginning near Buzzards Roost on the creek at what is now Slippery Rock Ford, running west to Fox Grape River, so called from the abundance of fox grapes growing there (now Lichliter's Branch)...

[3] Swimming place in the South Grape River in Luckenbach near the Luckenbach Inn Bed and Breakfast.

Answer 2

doubt it