Why Tehran Is Running Out of Water
wired.com
wired.com
For starters explore this rabbithole: https://en.wikipedia.org/wiki/Water_Mafia_in_Iran
I wonder if, today, the overall brain drain is contributing to the situation. Iranian engineers don't have to put up with the regime's shenanigans if they don't want to. How many of the people who could have managed the situation are abroad?
It's a combination of internal and external factors. Internally - wasting water and overpumping underground water table. Externally - climate change and Afghanistan damming couple of rivers flowing into Iran.