The chumash uses different names of G-d, particularly YK-VK vs. Elokim.
In Parshat Noach, most of the verses use the name Elokim, but some verses have YK-VK
The Netzivs approach is interesting and is a springboard for the methodology that Netziv uses in other parts of the chumash.
Bereishit 7:1 G-d (YK-VK) said to Noach, Come into the ark because I see that you are righteous before Me
HaAmek Davar: The entire story before the flood and immediately afterwards uses the name Elokim. Except for this narrative, where it uses YK-VK. Ramban has already discussed this. What is unique about this narrative is that G-d commands Noach to bring seven animals (as opposed to the two he was instructed to bring above), and these animals were to be used as sacrifices after the flood.
Ramban speaks about this at the beginning of Vayikra that with reference to sacrifices the name YK-VK is always used. He cites the Gemara in Menachot.
There is a lot of discussion about this Ramban, since it does not always fit with the verses of the Torah.
The scholars question the difference between the chumash and other ancient texts from a literary point of view.
Erich Auerbach wrote many essays which were published as a book called Mimesis.
In the first essay, Odysseus Scar he compares the Odyssey with the story of the akeida. He claims that the Greek text uses rhetoric, to bring the emotions and motives of the characters etc. Nothing is hidden from the reader. However, in the Torah there is a lot of information hidden from the reader. It is clear that there is an oral Torah which accompanies it.
Netziv takes a similar approach.
Most of the story of the flood is to ensure the preservation of the species, hence it is part of nature, and uses Elokim. However, here it describes that animals will serve man, and is ethical. So it uses the name YK-VK.
The name YK-VK shows us how we should read the chumash.
For example, when Chava says I have acquired a man for G-d Netziv points out that it uses YK-VK, so it cannot be speaking about the physical, natural process of birth, but rather an ethical message/dimension of the purpose of children and the relationship with G-d.
Netziv does not ask what the names of G-d mean, but rather, how we are to understand the chumash given the different meanings of those names.
The interpretation is built into the text (as implied by Rashis commentary on the word Vayikra at the beginning of Vayikra).
The purpose of the chumash is to bring the reader into the text and allows him to become part of the text.
It is only the reader who can complete the literary work the technique is to draw the reader into the text.
Bereishit 12:17 the Netziv uses Chazal as the means by which one is supposed to interpret the text. Not to understand how Chazal interpret, but Chazal lay down principles which are to be used by the reader.