I've put the word "evacuation" in the title of this piece in quotes because it's not clear where Tehran's 9.8 million people, or some significant number of them, would evacuate to as water supplies run dangerously low. Iranian President Massoud Pezeshkian has been criticized for saying out loud how bad the situation is: "If it does not rain in Tehran by December, we should ration water; if it still does not rain, we must empty Tehran." Doubtless, Iranian water authorities will force severe restrictions on Tehran's residents if the rains—which…