As far as dowsing goes, it’s as good as a random guess. Your guy might have been in a target rich environment.

I’ve only seen it done once, at a hotel parking lot in Arizona. They were looking for the sewer line using dowsing to avoid digging up the whole parking lot. A few days later, they found the line, but had dug several dry holes.

However, I am a believer in the power of intuition, that our brains can pick up on subtle clues we are not fully aware of.