Is Water and Gravity enough for a Super-being to be able to defeat Superman?

I want my character to "obviously be able to defeat Superman", but I want her to be the second most powerful character in the party of 4 initial heroes with the 5th hero added later.

This is "Kristen" again. She has complete control of water at "virtually unlimited scales" and can shapeshift into water and she controls gravity in the form of dimensional portals and "Gravity Rods" which can absorb and kill other water manipulators.

Her codenames are "Winter" and "Elementalist Superior".

If she were a Marvel character, she would be considered a "Double Omega Mutant" because she is Omega at both Water and Gravity.

How would she kill Superman, hypothetically? By ripping the water molecules out of his body at the molecular level, thus dehydrating him and instantly mummifying him.

Is Water and Gravity enough for a Super-being to be able to defeat Superman?
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