> However, unpublished national observations revealed groundwater depletion in some plains from as early as the 1950s.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.
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”?
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.
Sanctions, including an attempted blockade [1] of oil exports, imposed by the British Empire, still in existence at the time, in response to a dispute over the ownership of Iranian oil fields, which were a primary factor in the fall of Mossadegh. See e.g.:
It should be noted that while the Shah obviously benefited from the coup, he remained suspicious of the Western powers who had supported it; he was not foolish enough to believe they were honest allies. Consequently, he was inclined to support attempts at autarky.
We tend to forget that the 1950s and 1960s were a period of large-scale engineering: intensification of agriculture, massive construction of dams, roads, mines etc., where nature and environmental footprint was at best an afterthought. In the US, in the Soviet Union, and also in (the Shah's) Iran.
Current environmental movement is downstream from that period - a reaction to abuses that happened. At least where the political situation tolerated its emergence.
Note that the Aral Sea, which lies geographically nearby, dried up for nearly the same reasons - too much water consumed - even though the Soviet Union was not in a position where they "couldn't have done much different"; they had plenty of productive soil elsewhere, being literally the largest country in the world and having been blessed with a lot of chernozem.
The underlying factor was the technocratic Zeitgeist which commanded people to "move fast and break (old fashioned) things". Such as qanats in Iran or old field systems in Central Europe.
Afforestation, green houses, swales, center pivot irrigation and no till agriculture are highly effective methods that conserve water or let it accumulate in the local area.
Dams are highly ineffective when the goal is water conservation. Censorship and punishment are also highly ineffective methods for water conservation.
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.
Yes, they do, but if what goes in is insufficient by a wide margin, people who can afford to will start drilling for water.
Assuming that the water taken through qanats would eventually make it into aquifers (fat from unlikely, I think, as it takes water from underground that’s less likely to evaporate) one could even argue that tapping rainwater with qanats prevent aquifers from getting refilled, so it’s taking from the same water source.
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”?