In the account of Creation, we see that God separated the waters from the waters (Genesis 1:6-7) resulting in waters above and waters below.
Upon man’s exceeding wickedness, God’s wrath was poured out in the form of a flood, in which the fountains of the great deep (waters from below) were opened up and the windows of  heaven were opened (waters from above) (Genesis 7:11), in a sense UNDOING the separation of the waters, that God had DONE in the creation account.
And not forgetting his righteous servant, Noah, God sent a wind to pass over the earth, so that the flood waters could assuage and the fountains of the deep and windows of heaven were stopped, and the rain from heaven restrained, so that the water could recede. In other words, God had to REDO the separation and the earth was replenished by only those who were righteous.

So, in the matter of separation (of the waters), God had to DO, UNDO and REDO.

Points to ponder:
In like manner in our spiritual matters of being separate and sanctified (set apart) for the Lord, when God created man, he created him to be a living soul (Genesis 2:7). Man was distinct from the animals and everything else God created for man was created in the image (Holy image) of God (Genesis 1:27). But with man’s fall and exceeding wickedness, God had to pour forth his wrath on himself, as a flood (for the sins of the whole world was laid on Jesus Christ, God’s Only Begotten Son);  And when the Holy Spirit of God passes over us, receding the self and sin in us, making us believe in the Lord Jesus Christ, to be our Savior, we are redone in God’s image – recreated as a new creation (2 Corinthians 5:17).

Are you REDONE in the image of God, conforming no longer to the patterns of this world, but to the image of God’s Son, Jesus Christ?

Genesis 1:6-7 (KJV)
6 And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.

Genesis 7:11 (KJV)
11 In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.

Genesis 8:1-2 (KJV)
1 And God remembered Noah, and every living thing, and all the cattle that was with him in the ark: and God made a wind to pass over the earth, and the waters assuaged;
2 The fountains also of the deep and the windows of heaven were stopped, and the rain from heaven was restrained;

2 Corinthians 5:17 (KJV)
17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.