I first encountered this word reading Frank Herbert's Dune, so it was a bit odd when I encountered it in other literature. Later I realised one of the great things about Herbert's SF - he uses many real-world cultures as sources for his world building
Hah. I've just reread these, and I have been vaguely intending to look up 'qanat' to see if he made the word up.
Incidentally, I just came back from a holiday in Madeira --- amazing place if you like mountains; the average altitude of the island is 1300m --- and it's covered with a network of tiny canals called levadas. These collect trickles of water from the high summits, which are usually covered in cloud; it doesn't rain much. So they're kind of the opposite of a qanat. Instead of the water table being underground, it's way up high.
Epicly, a lot of the levadas are in grooves chipped into the side of cliff faces. You can just about extrapolate the slope in that picture. Unfortunately in the really scenic bits I was too worried about not falling off to take photos. Safety railings are things which happen to other people in Madeira...
For me it was like having an insight into the subtext of the series. Quite a lot of Persian (PadehShah for king) , Arabic (Karama for blessings) , and Islamic (Mahdi for The Guided One), for example.
