|Easton's Bible Dictionary|
Called by the Accadians id Idikla; i.e., "the river of Idikla", the third of the four rivers of Paradise (Genesis 2:14). Gesenius interprets the word as meaning "the rapid Tigris." The Tigris rises in the mountains of Armenia, 15 miles south of the source of the Euphrates, which, after pursuing a south-east course, it joins at Kurnah, about 50 miles above Bassorah. Its whole length is about 1,150 miles.
Int. Standard Bible Encyclopedia
hid'-e-kel (chiddeqel): One of the rivers of EDEN (which see) (Genesis 2:14, the Revised Version margin "that is, Tigris"; so Septuagint Tigris), said to flow East to Assyria, usually identified with the Tigris, which rises in Armenia near Lake Van and, after flowing Southeast through 8 degrees of latitude, joins the Euphrates in Babylonia to form the Shatt el-'Arab, which runs for 100 miles through a delta which has been formed since the time of Abraham, and now enters the Persian Gulf through 2 branches. About one-third of the distance below its source, and soon after it emerges from the mountains of Kurdistan, the Tigris passes by Mosul, the site of ancient Nineveh, and, lower down at Bagdad, approaches within a few miles of the Euphrates. Here and for many miles below, since the level is lower than that of the Euphrates, numerous canals are conducted to it, irrigating the most fertile portions of Babylonia.
George Frederick Wright
Hiddekel (2 Occurrences)
Genesis 2:14 The name of the third river is Hiddekel: this is the one which flows in front of Assyria. The fourth river is the Euphrates. (WEB KJV ASV DBY WBS YLT)
Daniel 10:4 In the four and twentieth day of the first month, as I was by the side of the great river, which is Hiddekel, (WEB KJV ASV DBY WBS YLT)