Albert Barnes Commentary Psalms 78:16

"He brought streams also out of the rock, And caused waters to run down like rivers." — Psalms 78:16 (ASV)

He brought streams also out of the rock ... - literally, "flowings." The waters were poured out in an overflowing stream. Those streams continued to flow, thus constituting a continued proof of the presence of God. See this fully explained in the notes at (1 Corinthians 10:4).