Qasabeh, sometimes written Ghasabeh, is the qanat of Gonabad, one of the oldest and longest living examples of Iran's underground water systems, and part of the UNESCO listing of Persian qanats. Its origin is said to go back some 2,700 years, and it still delivers water. The main channel runs for about thirty-three kilometres, drawing from a mother well that is some 340 metres deep, and reaches the surface at the town, where it irrigates farms and gardens. It was once thought to be the longest and deepest in the world, and its engineering still impresses.
A qanat is simple in principle. A tunnel with a slight downward slope carries water from an aquifer at the foot of the mountains to the surface, often over a long distance, and vertical shafts every few dozen metres allow workers to clean it and let air circulate. The people who dug them, the muqannis, were respected specialists who worked in dangerous conditions. At Gonabad you can see how the oasis depends on this water, with orchards of pistachios and pomegranates and fields of saffron in a landscape that would otherwise be desert.
Gonabad is a town of about forty thousand people, about eight kilometres from this point, and it has a long history, including as a centre of a Sufi order, the Gonabadi dervishes. The riding is the open kind, with wide, straight roads across the dry plains, backed by low brown ranges. The wind can be strong, bringing dust, and summers are very hot, so go in spring or autumn. The surface of the main roads is generally good, but side tracks can be rough, and animals sometimes cross.
Fuel and food are available in Gonabad, with petrol stations along the main road and kebab restaurants and tea houses. Fill your tank before heading out into the desert, and carry water. Visitors to the qanat are usually welcome, but ask first, and be careful near the shafts. It is worth taking a guide if one is offered, because the story of the water is the real attraction, and the local people are rightly proud of it.