Nebuchadnezzar relates that he constructed a large reservoir, which he calls the Yapur-Shapu, in Babylon, and led water into it by means of an "eastern canal"-- the Shebil.

The Shebil canal, it is probable, left the Euphrates at some point between Babil and the Kasr, and ran across with a course nearly from west to east to the top of the Yapur-Shapu.

This reservoir seems to have been a long and somewhat narrow parallelogram, running nearly from north to south, which shut in the great palace on the east and protected it like a huge moat.

Most likely it communicated with the Euphrates towards the south by a second canal, the exact line of which cannot be determined.

Thus the palatial residence of the Babylonian kings looked in both directions upon broad sheets of water, an agreeable prospect in so hot a climate; while, at the same time, by the assignment of a double channel to the Euphrates, its floods were the more readily controlled, and the city was preserved from those terrible inundations which in modern times have often threatened the existence of Baghdad.
The other lines of mound upon the east side of the river may either be Parthian works, or (possibly) they may be the remains of some of those lofty walls whereby, according to Diodorus, the greater palace was surrounded and defended.