River of Egypt

Concise Bible Dictionary:

The S.W. border of the promised land was to be from “the river of Egypt” (Gen. 15:18). Here the word is nahar, and would seem to allude to the most eastern branch of the Delta of the Nile, called the Pelusiac mouth. In Numbers 34:5 “the river of Egypt” has the word nachal, signifying a winter torrent, and is supposed to refer to the Wady el Arish, 31° 8' N, 33° 50' E.