"Little by little, the water becomes less deep."
Translation:Petit à petit l'eau devient moins profonde.
Could you not say. ."Peu à peu" instead of "petit à petit"? Or is that just wrong?
Can "petite" not be used here because "l'eau" is masculine? Or is there a different reason?
"petit à petit" is an adverbial phrase, like "peu à peu" which means the same thing.
It is singular, that's why it's "l'eau devient". If it was plural it would be "les eaux devieNNENT".