The Evil Engineer advises a dictator on how to get one over a rival by rerouting a river away from his borders.

Dear Evil Engineer,

I am the dictator of a small landlocked state. I have a long-running feud with the dictator of a neighbouring small landlocked state, which began the day he gave me a swirlie when we were at public school together.

Last year, he spread misinformation claiming that my country smells of Stilton. I responded by flying drones over the border blasting a Kidz Bop cover of his country’s national anthem at 165dB. After some weeks of cowed silence, I assumed that was the end of it, but then I discovered he had released feral hogs on my side of the border; already they are multiplying and causing chaos for my farmers.

I’ve decided that, in retaliation, I’d like to steal the river that flows through my country and into his. Can I reroute it such that it does not enter his country at all?

Yours,A feuding villain

Dear villain,

A wise man might advise that an eye for an...