Qanat or kariz is an ancient system of underground tunnels that supply mountain water to dry lower places by gravity. An ancient irrigation system consisting of a tunnel dug at a very slight upward gradient into the rising ground so that water from deep within the earth runs out to the surface for irrigation and drinking. Qanats were developed in Persia and later adopted throughout the Middle East and North Africa.

Location: Zārch is a 22 km² town and a part of Yazd-Ardakān great plain located in an arid area with low precipitation, high temperature and high evaporation. There is no permanent river or superficial runoffs so groundwater is the only water resource which was provided by qanats. There are several important qanats in Zārch region, the most important of which is Zārch.

Catchment: This catchment holds the biggest water storage of Yazd province. The supply of this plain is provided by the upper areas of Siyah Kuh desert. The plain benefits from no permanent rivers, but several seasonal runoffs originating from the northern foothills of Siyah Kuh enter it.

Relevant structures

Main Branches and Shafts: It has three branches named: Shur, Shirin and Ebrāhim Khavidaki, the first of which is operational now. The total length of this qanat is about 80 km.

Mother well: This qanat has 4 mother wells. The main mother well is the mother well of Shur branch located at 3 km distance from Fahraj village in SE of Yazd with the depth of 90 m and has a discharge of about 25 litres/second.

Chāh Khāneh: In the past, a specific well was dug in the houses of affluent residents or the proximity of public hammams situated near the course of a qanat.

Pāyāb: Pāyāb in local dialect refers to a sloped corridor-like passageway which is dug underground to connect qanat tunnel to the earth surface. These corridors provide access to qanat water.

Golkarpayab is the first payab which is located on the course of qanat from its mother well. Because of its long depth and lack of any materials in its construction, this payab has become a tourist attraction nowadays.

Watermill: There are several āsiyāb (watermills) along the course Qanat of Zārch, one of which is Vazir āsiyāb. It is located in a large square called Lord āsiyāb.

Āb Anbār: Āb anbār is an underground structure, constructed in the past to store freshwater for domestic uses. The water reservoir was fed from a near shallow qanat. The city of Yazd did not have piped water network until 1961 so that people had to provide their potable water from āb anbār which was filled mostly by qanat waters.

Water Heritage

Qanat of Zarch is the longest recorded qanat in the world which is located in Yazd province of Iran with a gallery length of 80 km, mother well depth of 90 m and more than a thousand shafts.

As the sub-branches join the main branch qanat of Zarch, it passes through Yazd and finally ends up in Zarch. The supplying resources of aquifers are located in the upper parts of Fahraj and Khavidak which are mostly situated in the vicinity of Mehriz. It has a gradient of about 0.5 percent. The distance between well shafts in the newer pishkar is 170 m whereas the distance between them in the old pishkar is 80 m and decreases to 50 m in khoshkan. The well shafts have a diameter about 75-80 cm, the height of the gallery is 1.8 m and its width is 60 cm. In addition to circular well shafts, there are some Square- shaped shafts of 60×100 cm size. It is claimed that digging these wells dates back to pre- Islamic Era.

In such an arid area with very hot weather during summer times its water was used for drinking, sanitation and irrigation purposes, but nowadays it is only used for irrigating of a few farms in Zārch. This qanat used to irrigate about 300 ha of farms and gardens of Zārch in the past which was a miracle during those past years and in ancient times.’

Water Distribution Management

The Qanat of Zārch has a perfect system of water sharing measurement and ownership. The irrigation cycle of this qanat is once every 15 days, in other words, each farmer can use his water every 15 days. These cycles amount to 24 rounds per year. Each round is 140 Joré and each Joré is broken down to 6 Dongs or shares. Therefore, the 15 day's cycle of water consists of 12,600 shares or 2,100 Joré.

To measure irrigation time at Qanat of Zārch, the old method of tub and bowl (water clock) has been used. The bowl takes about 10 minutes and 17 seconds to sink in the tub, this time interval is called a joré. There are some lines inside the tub which show smaller units dividing the entire space into 6 sections each of which is equal to one share. Each joré was equal to six shares.

The Qanat of Zārch is managed by the qanat council, benefiting from a custodian to deal with its affairs. In addition, some other people, including the supervisor, manager and water distributor with defined duties are involved in the matter. Furthermore, a representative was traditionally appointed to investigate issues. The qanat is owned by the farmers. Research on records kept in the register office of Zārch identified 1037 stakeholders, holding 11,656 shares out of 12,600 the ownership of the other 944 shares remains uncertain, probably because of unregistered shareholders.

It is worth mentioning that the main stakeholders and farmers of the qanat include some wealthy citizens of Yazd, as well as some residents of Sarcheshme and Tudeh in Zārch, who rent out their water shares to farmers. Sometimes the irrigated lands exceed the water shares and farmers are forced to rent more water under the supervision of qanat manager- even though his main duty is to handle the water distribution-related affairs, he is quite knowledgeable about the shareholders, farmers and water rights.

Present State of Conservation

In recent years, Zārch has been used for the irrigation of crop fields. The areas irrigated by this qanat are estimated to be about 300 hectares, which shows the effective role of this qanat in agricultural domains of this region. This qanat consists of three branches called Shur, Shirinand Ebrīhim Khavidaki. The only operational branch is Shur. The qanat has some new wet zones of about 250 m long have been added to it in the past 25 years. The well shafts in the new wet zone are spaced at 170 m distance while in the old wet zone they are spaced at 80 m distance from each other, this distance decreases to 50 m in the dry zone of qanat. The overall structure of qanat has been preserved and it is in good working condition.

On some parts of qanat’s course at Nosrat Ābād district, parts of galleries’ roofs have been reinforced by stone works to prevent a cave-in. Nowadays “kavalsare” used in galleries and well shafts to prevent further damage. There is no gaseous zone on the routes of Qanat of Zārch, therefore there has been no need for the digging of Jofte Bādoo wells6. Like other qanats, Zārch has received effective maintenance works during the past few years, measures taken include: lāyroobi, paving, kaval gozāri8 and pishkār kani.