alt Hacker News> However, unpublished national observations revealed groundwater depletion in some plains from as early as the 1950s. This coincided with the gradual replacement of Persian qanats, which were sustainable groundwater extraction systems and UNESCO World Cultural Heritage sites9, with (semi)deep wells.
https://www.macrotrends.net/global-metrics/countries/irn/ira... says Iran’s population today is over five times that of 1950.
It also is a safe bet that water consumption per capita went up, too.
It wouldn’t surprise me at all if qanats couldn’t support current water usage.
Maybe that “coincided” doesn’t imply “they stopped using qanats, so the water table dropped” but “qanats weren’t sufficient anymore, so they started drilling deep wells, and the water table dropped”?
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The article does say that a number of qanats was overdrawn.
But it also says several other things, pointing to poor water management policies, extreme damification drying up wetlands downstream, lack of necessary maintenance on some qanats, and more.
And the reason qanats weren't sufficient anymore, was that they pursued a policy of food independence, due to sanctions/a desire for political autonomy.
I'm not so sure they could have done much different.
Clicking through the link to the original paper, the point seems to be that qanats are inherently sustainable because they only produce as much as goes in. You may gradually exceed their capacity, but there won’t be a sudden “oops, no more water” crisis as can happen when you pump an aquifer dry.
The article interviewed some actual hydrologists from Iran. I’m pretty sure they are aware of population growth in their homeland.