one could define the term drought and cite rainfall levels, thereby demonstrating the point. but, it's also missing the point - which is that he's peddling fantasies to people who have had their hopes shattered. it's the thing that religions do. it's predatory, really. so, that evidence is not the solution to a reasonable debate but the shattering of one's dreams. there's a process here. denial. anger. more denial. acceptance. but, not everybody gets through it.
you really can't argue with him.
if i were clinton, i would refuse to debate him at all. i'd offer a press release describing him as a pathological liar that is not worth debating, or even listening to. and, i'd have a think tank dedicated to debunking every speech, offhand remark and anecdote that he spews - which would be a full time job for many people.
http://www.huffingtonpost.com/entry/trump-water-california_us_574910e0e4b03ede4414f435
this isn't "let's have a reasonable debate".
this is more like "don't feed the troll. ignore him and he'll go away."
and, i'm not joking. i would campaign as thought he doesn't exist. i would bring think tank people with me to the news conferences and duck the questions, instead allowing the experts to debunk him with citations and references to web sites.
this can't be thought of as an election between two candidates. it doesn't matter who wins - the country loses when we take this seriously. rather, it needs to be thought of as a teachable moment. she needs to create a kind of teacher-student dynamic. she should talk down to him at every opportunity. this has to be a no-brainer, unless you avoid voting altogether (which i still suggest).
she has to treat him like a complete, utter, total fucking retard.
the bureau of debunking that fucking idiot, trump.