Her sea - Probably the great lake dug by Nitocris to receive the waters of the Euphrates.
Her springs - Her reservoir; the whole system of canals dug Jeremiah 51:13. The wealth of Babylonia depended upon irrigation.
Related Commentaries of Jeremiah 51:36
Jeremiah 51:36
36 Therefore thus saith the LORD; Behold, I will plead thy cause, and take vengeance for thee; and I will dry up her sea, and make her springs dry.