Last Friday in Delft, the Netherlands, while attending a conference of the International Water History Association, I attended a session discussing water and culture. One of the presenters discussed the geographical distribution and evolution of one technical word (the arabic expression for water tank) as it spread throughout the Arab/Berber world. Since the word for the tank was similar across many cultures, he assumed this meant a common origin for the technology. While his presentation was interesting, it was the discussion afterward that was more informative for me.
I asked the presenter about the word “qanat,” which is the name for an underground water development system that some believe originated in Persia (modern-day Iran). From Persia, the qanat technology was believed to have moved east as far as China along the Silk Route, and west across North Africa to Spain with the arab expansion. The presenter indicated that the word for a qanat varied widely based on geography. This caused him personally to believe that qanat technology developed independently in several areas and didn’t have a unique birthplace.
One Chinese publication shows the similarities between qanat tunnels and another tunnel in China. Thus, suggesting that the qanats in western China may have developed independently from Persian qanats. If you look at Roman tunnel technology, it also looks similar to qanat tunnels. So maybe it is possible that the technology developed independently in several different. But I have my doubts.