The word arson derives from the Latin word for burning; the Latin word for flooding is inundo, so your closest match is something like inundationist, though I don't think this word is attested, and inundate isn't considered criminal.

The word arson derives from the Latin word for burning; the Latin word for flooding is inundo. So your closest match is something like inundationist, though I don't think this word is attested, and inundate isn't considered criminal.