These appear as craters from above, following the line of the qanat from water source to agricultural settlement. The levels, gradient and length of the qanat are calculated by traditional methods requiring the skills of experienced qanat workers and have been handed down over centuries. Criterion (iii): The Persian Qanat system is an exceptional testimony to the tradition of providing water to arid regions to support settlements. Criterion (iv): The Persian Qanat system is an outstanding example of a technological ensemble illustrating significant stages in the history of human occupation of arid and semi-arid regions. The eleven qanats are managed under traditional supervision of qanat councils, each qanat with its local qanat council composed of those knowledgeable in the respective region.