Those verses are referring to "like as it was to Israel in the day that he came up out of the land of Egypt", as Isaiah himself tells the readers (verse 16.)
Further on, chapter 19:23-25, the astounding reversal among the nations is further stated. Instead of Israel having been captive in Assyria (prior to which she was captive in Egypt), Israel is now:
"the third with Egypt and with Assyria, and the Egyptians shall serve
with the Assyrians, both peoples being called by God 'my people... and
the work of my hands, and Israel mine inheritance'."
This is symbolic of how Psalm 87 would be fulfilled, with Gentiles being counted as "Zion-born" even though they never were, literally, born in Zion. Spiritually, the new birth applies to Gentiles as well as to Jews. That is how both Gentiles and Jews come to be called "my people" with the advent of the New Covenant in Christ's shed blood.
However, if you are looking for some literal fulfilment in the spiritual aspects of Isaiah's prophecy, you will look in vain. There are not literally seven streams - the number seven is symbolic of heavenly perfection. It is a complete number. Streams of living water come from all those who are filled with the Holy Spirit, be they Jews or Gentiles (John 7:38). In the heavenly New Jerusalem, "the nations of them which are saved shall walk in the light of [the Lamb]" (Rev.21:24) with one river of water of life coming from the throne of God and of the Lamb (Rev.22:1). All who are thirsty are invited to drink from this one source of living water, freely (Rev.22:17).
There is great danger in seeking to apply all such prophecies of Isaiah to a literal nation of Israel restored to a tiny tract of land at some time in the future. That leads to all sorts of difficulties, such as trying to make the literal dimensions of the heavenly New Jerusalem fit into that literal, earthly, tract of land.
You specifically asked if the scripture you mention is connected to Revelation 16:12. In light of my answer, I would say "No, this symbolic river Euphrates speaks of spiritual events leading directly to the battle of Armageddon, where demons gather the nations together."
"What is Isaiah 11:15 referring to?" you ask. In the first instance, it had direct fulfilment in God restoring a remnant of Israel to the literal land of Israel, but at the start of that chapter it foretells a future coming of "a rod out of the stem of Jesse, and a Branch shall grow out of his roots." Then it gives a prophecy fulfilled in Christ, on earth (John 3:26-36). From the time of Christ's ascension back to heaven, to receive the Kingdom, up till this very day, Isaiah's prophecy is having its symbolic fulfilment in believing people of all nations being given streams of living water by the indwelling Holy Spirit. There will be a culmination after the Day of Judgment and Resurrection as per Revelation chapters 21 & 22.