'Canal' in the Bible

I looked in the vision, and while I was looking I was in the citadel of Susa, which is in the province of Elam; and I looked in the vision and I myself was beside the Ulai Canal.

Then I lifted my eyes and looked, and behold, a ram which had two horns was standing in front of the canal. Now the two horns were long, but one was longer than the other, with the longer one coming up last.

He came up to the ram that had the two horns, which I had seen standing in front of the canal, and rushed at him in his mighty wrath.