How can I make the blur panel in three.js?

As you can see in the current photo, the bottom of the model submerged in water is very clearly visible.
So I’m trying to cover the blur panel so that the bottom part is blurred out. So I hope you guys can help me with that.

Actually, ‘blured’ is somehow vague in regards of the real phenomenon, which sould be closer to ‘turbulence’.

If that is what you are after for, take a look at:

Maybe add gradient to sand from bottom to center between bottom and coast.