Poetry expresses artistic conception. Imagine David praising the Lord like this. What does he want to express?
The "flood" is based on Noah's flood, suggesting that Jehovah is the god in charge of nature; Yesterday, today ... forever. With such a god to protect you, what are you afraid of? Therefore, if you read 1 1 again, the people will have strength and peace. Although they are in trouble, they feel safe! Isn't it?