Compare Ezek 35.8, where God pronounces destruction on Edom in this language. The translator needs to preserve the imagery, but should not forget that the main point here is that Nebuchadnezzar is making a vicious threat.

Till their wounded shall fill their valleys, and every brook and river shall be filled with their dead: Filled is a passive verb. In languages that do not have the passive voice, Good News Translation‘s translation will be helpful:

• I will fill the valleys with their dead bodies and will choke up every stream and river with so many corpses….

However, in languages that prefer the passive, Contemporary English Version‘s translation will serve as a good model:

• The valleys and gorges will be filled with wounded people, and the land will be flooded, because dead bodies will block every stream and river.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Judith. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here.