Obviously, compared to other means of transporting water at that time! For example an “open” river could have been more vulnerable in certain circumstances. St

Obviously, compared to other means of transporting water at that time! For example an “open” river could have been more vulnerable in certain circumstances. Strong earthquakes may affect the path of the rivers as well. But I see your point in that, resistance to earthquakes or adversities are not what Qanat/Kariz were famous for (as far as we know).