And the streams thereof; i.e. "the streams of the land of Edom." Though Edom has no perennial rivers, it has numerous torrent-courses to carry off the winter rains (see 2 Kings 3:20-22). These should run with pitch, instead of water.
The general idea is that Edom should be visited with a destruction like that of Sodom and Gomorrah (Genesis 19:24; comp. Jeremiah 49:18). But the prophet scarcely intends his words to be taken literally; he is making Edom a type or representation of God's enemies, and the gist of his teaching is that a dreadful vengeance, an utter destruction, will come upon all who set themselves up against the Most High.
In the next verse he declares that the vengeance will be eternal (comp. Isaiah 66:24).