[Hermann the Cherusker]

The Bible is quite clear that the Garden of Eden is at the source of the four rivers named - i.e. the headwaters, not their confluence. So it never would have been anywhere near lower Iraq

As some more astute observers have mentioned, it is highly likely that the rivers mentioned are mistranslations. It has been suggested that the Pamir Plateau, and the four rivers flowing forth from the "Roof of the World" are the actual location.

[Elsie]

 Genesis Chapter 2

 

 8.  Now the LORD God had planted a garden in the east, in Eden; and there he put the man he had formed.
 9.  And the LORD God made all kinds of trees grow out of the ground--trees that were pleasing to the eye and good for food. In the middle of the garden were the tree of life and the tree of the knowledge of good and evil.
 10.  A river watering the garden flowed from Eden; from there it was separated into four headwaters.
 11.  The name of the first is the Pishon; it winds through the entire land of Havilah, where there is gold.
 12.  (The gold of that land is good; aromatic resin and onyx are also there.)
 13.  The name of the second river is the Gihon; it winds through the entire land of Cush.
 14.  The name of the third river is the Tigris; it runs along the east side of Asshur. And the fourth river is the Euphrates.
 15.  The LORD God took the man and put him in the Garden of Eden to work it and take care of it.
 16.  And the LORD God commanded the man, "You are free to eat from any tree in the garden;
 17.  but you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die."