Since distant past, there were a number of scholars in different regions of Iran which, according to the geographical situation of each place, used certain methods for protection and maintenance of the Qanats (underground aqueducts), which sometimes were significantly efficient.
With the construction of first deep wells that were dug by the Americans in the year 1949 with the aim of providing water for their camps and with no attention to their negative impact on Qanats, the number of Qanats was reduced, so that from the 62,932 Qanats of Iran, 20,967 have been abandoned.
There is no detailed information on the history of excavation of the first Qanats in Iran, but Megasthenes, in the year 300 BC, has reported on the existence of Qanats in Baluchistan.
In this paper, the major causes of decline of Qanats have been studied as follows:
- Digging deep and semi-deep wells
- Decrease in the stable level of groundwater
- Government and people's neglect of the importance of Qannats
At the end of the paper, using field methods, a successful case of using modern and traditional methods for optimization and exploitation of Qanats has been studied. The traditional way of creating dams on waterways in the vicinity of a head well and on the path of Qanat, terracing the land along the natural slope and along the Qanat route are carried out in order to prevent the flow of rain water and its penetration into ground and to increase the water-provision by Qanat, and the modern method includes the transfer of water by a pump engine to a distance of 1000 meters and its distribution through pipe network to the farm side. The three major results of the implementation of the plan are as follows:
- Use of total volume of aquifer and 50% increase in rate of water provision
- Use of the upstream areas of the Qanat head well and cultivation of about 100 hectares of fresh land
- Creation of nutritional conditions for aquifer using soil mound, terracing and tree plantation method.