(from ) (Iran, Syria and Jordan),
Afghanistan, Pakistan and Central Asia, derived from ),
(from ), khettara
(United Arab Emirates and Oman); Kahn
(North Africa) is a water management
system used to provide a
reliable supply of water to human settlements and for irrigation
in hot, arid
semi-arid climates. Alternative terms for Qanats in Asia and North
Africa are kakuriz
. Common variant spellings/transliterations of
in English include kanat
. Closely related to such structures is the
system in China. The technology
is known to have developed in ancient Iran, and then
spread to other cultures.
The value of a qanat is directly related to the quality, volume and
regularity of the water flow. Much of the population of Iran and
other arid countries in Asia and North Africa historically depended
upon the water from qanats; the areas of population corresponded
closely to the areas where qanats are possible. Although a qanat
was expensive to construct, its long-term value to the community,
and therefore to the group who invested in building and maintaining
it, was substantial.
Cross-section of a Qanat.
Qanats are constructed as a series of well-like
, connected by gently sloping tunnels
tap into subterranean water in a manner that efficiently delivers
large quantities of water to the surface without need for pumping.
The water drains relying on gravity
the destination lower than the source, which is typically an upland
. Qanats allow water to be
transported over long distances in hot dry climates without losing
a large proportion of the water to seepage and evaporation
It is very common in the construction of a qanat for the water
source to be found below ground at the foot of a range of foothills
of mountains, where the water table is closest to the surface. From
this point, the slope of the qanat is maintained closer to level
than the surface above, until the water finally flows out of the
qanat above ground. To reach an aquifer qanats must often be of
Qanats are sometimes split into an underground distribution network
of smaller canals called kariz
. Like Qanats,
these smaller canals were below ground to avoid contamination. In
some cases water from a Qanat is stored in a reservoir, typically
storing night flow for daytime use. An Ab
is an example of a traditional qanat fed reservoir for
drinking water in Persian antiquity.
The qanat system has the advantage of being relatively immune to
natural disasters (earthquakes, floods…) and human destruction in
war. Further it is relatively insensitive to the levels of
precipitation; a qanat
typically delivers a relatively
constant flow with only gradual variations from wet to dry
Features common to regions which use qanat technology
The qanat technology is used most extensively in areas with the
- An absence of larger rivers with year-round flows sufficient to
- Proximity of potentially fertile areas to precipitation-rich
mountains or mountain ranges.
- Arid climate with its high surface evaporation rates so that
surface reservoirs and canals would result in high losses
- An aquifer at the potentially fertile
area which is too deep for convenient use of simple wells.
Impact of qanats on settlement patterns
A typical town or city in Iran and elsewhere where the qanat is
used has more than one qanat. Fields and gardens are located both
over the qanats a short distance before they emerge from the ground
and after the surface outlet. Water from the qanats defines both
the social regions in the city and the layout of the city.
The water is freshest, cleanest, and coolest in the upper reaches
and more prosperous people live at the outlet or immediately
upstream of the outlet. When the qanat is still below grade, the
water is drawn to the surface via water
or animal driven Persian
. Private subterranean reservoirs could supply houses and
buildings for domestic use and garden irrigation as well. Further,
air flow from the qanat is used to cool an underground summer room
) found in many older houses and
Downstream of the outlet, the water runs through surface canals
called jubs (jūbs
) which run downhill, with lateral
branches to carry water to the neighborhood, gardens and fields.
The streets normally parallel the jubs and their lateral branches.
As a result, the cities and towns are oriented consistent with the
gradient of the land; what is sometimes viewed as chaotic to the
western eye is a practical response to efficient water distribution
over varying terrain.
The lower reaches of the canals are less desirable for both
residences and agriculture. The water grows progressively more
polluted as it passes downstream. In dry years the lower reaches
are the most likely to see substantial reductions in flow.
Traditionally qanats are built by a group of skilled laborers,
, with hand labor. The profession historically
paid well and was typically handed down from father to son.
The critical, initial step in qanat construction is identification
of an appropriate water source. The search begins at the point
where the alluvial fan meets the mountains or foothills; water is
more abundant in the mountains because of orographic lifting
and excavation in the
is relatively easy. The
follow the track of the main water courses coming
from the mountains or foothills to identify evidence of subsurface
water such as deep-rooted vegetation or seasonal seeps. A trial
well is then dug to determine the location of the water table and
determine whether a sufficient flow is available to justify
construction. If these prerequisites are met, then the route is
laid out aboveground.
Equipment must be assembled. The equipment is straightforward:
containers (usually leather bags), ropes, reels to raise the
container to the surface at the shaft head, hatchets and shovels
for excavation, lights, spirit levels or plumb bobs and string.
Depending upon the soil type, qanat liners (usually fired clay
hoops) may also be required.
Although the construction methods are simple, the construction of a
qanat requires a detailed understanding of subterranean geology and
a degree of engineering sophistication. The gradient of the qanat
must be carefully controlled—too shallow a gradient yields no
flow—too steep a gradient will result in excessive erosion,
collapsing the qanat. And misreading the soil conditions leads to
collapses which at best require extensive rework and, at worst, can
be fatal for the crew.
Construction of a qanat is usually performed by a crew of 3-4
. For a shallow qanat, one worker typically digs
the horizontal shaft, one raises the excavated earth from the shaft
and one distributes the excavated earth at the top.
The crew typically begins from the destination to which the water
will be delivered into the soil and works toward the source (the
test well). Vertical shafts are excavated along the route,
separated at a distance of 20-35 m. The separation of the shafts is
a balance between the amount of work required to excavate them and
the amount of effort required to excavate the space between them,
as well as the ultimate maintenance effort. In general, the
shallower the qanat, the closer the vertical shafts. If the qanat
is long, excavation may begin from both ends at once. Tributary
channels are sometimes also constructed to supplement the water
Most qanats in Iran run less than 5 km. The overall length of
the qanat often runs up to 16 km, while some have been
measured at ~70 km in length near Kerman.
vertical shafts usually range from 20 to 200 meters in depth,
although in Iran qanats in the province of Khorasan
have been recorded
with vertical shafts of up to 275 m. The vertical shafts support
construction and maintenance of the underground channel as well as
air interchange. Deep shafts require intermediate platforms to
simplify the process of removing spoils.
The qanat's water-carrying channel is 50-100 cm wide and
90-150 cm high. The channel must have a sufficient downward
slope that water flows easily. However the downward gradient must
not be so great as to create conditions under which the water
transitions between supercritical
and subcritical flow
; if this
occurs, the waves which are established result in severe erosion
and can damage or destroy the qanat. In shorter qanats the downward
gradient varies between 1:1000 and 1:1500, while in longer qanats
it may be almost horizontal. Such precision is routinely obtained
with a spirit level
In cases where the gradient is steeper, underground waterfalls may
be constructed with appropriate design features (usually linings)
to absorb the energy with minimal erosion. In some cases the water
power has been harnessed to drive underground mills. If it is not
possible to bring the outlet of the qanat out near the settlement,
it is necessary to run a jub
or canal overground. This is
avoided when possible to limit pollution, warming and water loss
due to evaporation.
The construction speed depends on the depth and nature of the
ground. If the earth is easy/soft to work; at 20 meters depth, a
crew of 4 people can excavate a horizontal length of 40 meters per
day. When the vertical shaft reaches 40 meters, they can only
excavate 20 meters horizontally per day and at 60 meters in depth
this drops below 5 horizontal meters per day. In Algeria, a common
speed is just 2m per day at 15m depth. Qanats are abandoned,
regardless of depth reached, on hitting a solid rock layer. Deep,
long qanats (which many are) require years and even decades to
The excavated material is usually transported by means of leather
bags up the vertical shafts. It is mounded around the vertical
shaft exit, providing a barrier that prevents windblown or rain
driven debris from entering the shafts. From the air, these shafts
look like a string of bomb craters.
The vertical shafts may be covered to minimize in-blown sand. The
channels of qanats must be periodically inspected for erosion or
cave-ins, cleaned of sand and mud and otherwise repaired. Air flow
must be assured before entry for human safety.
Some damaged Qanats have been restored. In order to be sustainable,
restoration needs to take into account many other factors than
technical factors, beginning with the process to select the Qanat
to be restored. In the case of Syria, three sites were chosen based
on a national inventory conduced in 2001. One of them, the Drasiah
qanat of Dmeir
completed in 2002. Selection criteria included the availability of
a steady groundwater flow, social cohesion and willingness to
contribute of the community using the qanat, and the existence of a
functioning water rights system.
Applications of qanats
Irrigation and drinking water supply
The primary applications of qanats are for irrigation, providing
cattle with water and drinking water supply. Other applications
include cooling and ice storage.
Wind tower and qanat used for
Qanats used in conjunction with a wind
can provide cooling as well as a water supply. A wind
tower is a chimney-like structure positioned above the house; the
one of its four openings opposite the wind direction is opened to
move air out of the house. Incoming air is pulled from a qanat
below the house. The air flow across the vertical shaft opening
creates a lower pressure (see Bernoulli effect
) and draws cool air
up from the qanat tunnel, mixing with it. The air from the qanat
was drawn into the tunnel at some distance away and is cooled both
by contact with the cool tunnel walls/water and by the giving up
of evaporation as water
evaporates into the air stream. In dry desert climates this can
result in a greater than 15°C reduction in the air temperature
coming from the qanat; the mixed air still feels dry, so the
basement is cool and only comfortably moist (not damp). Wind tower
and qanat cooling have been used in desert climates for over 1000
In 400 BC
Persian engineers had already mastered the technique of
storing ice in the middle of summer in the desert.
The ice was brought in during the winters from nearby mountains in
large quantities, and stored in specially designed, naturally
cooled refrigerators called yakhchal
(meaning ice pits
). A large underground space with thick
insulated walls was connected to a qanat, and a system of windcatchers
was used to draw cool subterranean
air up from the qanat to maintain temperatures inside the space at
low levels, even during hot summer days. As a result, the ice
melted slowly and ice was available year-round.
Qanats by country
Probable diffusion of Qanat
The Qanats, called Kariz (rhymes with "breeze") in Pashto
, have also been in use for
hundreds of years. Kariz structures are especially found in the
Southern Afghanistan provinces of Kandahar, Uruzgan, Nimroz and
Hilmand. The incessant war for the last 30 years has destroyed a
number of these ancient structures. In the troubled times
maintenance was not always possible. To add to the troubles, at
present (2008) the cost of labour has become very high and
maintaining the Kariz structures is no longer possible . Lack of
skilled artisans who have the traditional knowledge also poses
difficulties. A number of the large farmers are abandoning their
Kariz which has been in their families sometimes for centuries, and
moving to tube and dug wells backed by diesel pumps .
However the government of Afghanistan is aware of the importance of
these structures and all efforts are being made to repair,
reconstruct and maintain (through the community) the kariz . The
Ministry of Rural Rehabilitation and Development along with
National and International NGOs is making the effort.
Still, there are functional qanat systems in 2009. American forces
are reported to have
unintentionally destroyed some of the channels during expansion of
a military base, creating tensions between them and the local
at Turpan in the
deserts of northwestern China uses water
provided by qanat (locally karez).
Turfan has long
been the center of a fertile oasis and an important trade center
along the Silk Road's northern route, at which time it was adjacent
to the kingdoms of Korla and Karashahr to the southwest. The
historical record of the karez system extends back to the Han Dynasty
. The Turfan Water Museum (see photos on this
page) is a Protected Area
of the People's Republic of China because of the importance of
the local karez
system to the history of the area.
The number of
karez systems in the area is slightly below 1,000 and the total
length of the canals is about 5,000 kilometers in length.
Karnataka, India, a Qanat-type structure called Suranga is
used to tap underground water.
But these are rarely in use
these days .
In the middle of the twentieth century, it is estimated that
approximately 50,000 qanats
were in use in Iran, each
commissioned and maintained by local users.
four-fifths of the water used in the plateau
regions of Iran is brought
to use in this way.
However, because agriculture is less and
less practiced in Iran, the qanats that are being made now are not
as effective as those made in the past because knowledge of how to
make them is being lost . Also, the construction and maintenance of
a qanat is unpleasant and dangerous, and modern technology allows
water to be pumped from a drilled well. Hence although qanats still
exist, they are falling out of use .
The oldest and largest known qanat is in the Iranian city of
which after 2700 years still
provides drinking and agricultural water to nearly 40,000 people.
Its main well
depth is more than 360
meters and its length is 45 kilometers. Yazd, Khorasan and Kerman are the
known zones for their dependence with an extensive system of
In traditional Persian
, a Kariz
(کاریز) is a small Qanat,
usually within a network inside an urban setting. Kariz is what
distributes the Qanat into its final destinations. (see also
sources of Persian antiquity
and Ab Anbar
of Qanat systems in the Kurdistan region of Iraq conducted by the
Department of Geography at Oklahoma State University (USA) on behalf of UNESCO in 2009
found that out of 683 karez systems, some 380 were still active in
2004, but only 116 in 2009.
Reasons for the decline of
qanats include "abandonment and neglect" previous to 2004,
"excessive pumping from wells" and, since 2005, drought. Water
shortages are said to have forced over 100,000 people who depended
on karez systems for their livelihoods to leave their homes since
2005. The study says that a single karez has the potential to
provide enough household water for nearly 9,000 individuals and
irrigate over 200 hectares of farmland. UNESCO and the government
of Iraq plan to rehabilitate Karez through a Karez Initiative for
Community Revitalization to be launched in 2010. Most of the karez are
Governorate (84%). A large number are also found in Erbil
Governorate (13%), especially on the broad plain around and in
qanats built in the Roman Empire was
the possibly longest continuous qanat ever built, the recently
discovered, 94 km long Gadara
qanat in northern Jordan from the 2nd
p 25, 32
This qanat remained in use until the Muslim conquest
Chagai district is in the north west corner
of Balochistan, Pakistan, bordering with Afghanistan and Iran.
Karez's are found more broadly in this region. They are spread from
Chaghai district all the way up to Zhob
A number of them are present in Qilla Abdullah
districts. Karez's are also extensively found
in the neighbouring areas of Afghanistan like Kandahar. The remains
of qanats (called karezes
) found in different
parts of the district are attributed to the Arabs
Qanats were found over much of Syria. The widespread installation
of groundwater pumps has lowered the water table and qanat system.
Qanats have gone dry and been abandoned across the country.
United Arab Emirates
Ain in the United Arab Emirates continues traditional falaj (qanat)
irrigations for the palm-groves and gardens.
According to UNESCO some 3,000 qanat systems, called Aflaj (plural)
of Falaj (singular), are still in use in Oman today. Nizwa, the former
capital city of Oman, was built
around a falaj which is in use to this day.
In July 2006,
five representative examples of this irrigation system were
inscribed as a World Heritage
There are 4 main oases in the Egyptian desert. The Kharga Oasis is one of them which has been extensively
As early as the second half of the 5th century BC
there is evidence that water was being used via qanats. The qanat
is excavated through water-bearing sandstone rock which seeps into
the channel to collect in a basin behind a small dam at the end.
The width is approximately 60 cm, but the height ranges from 5
to 9 meters; it is likely that the qanat was deepened to enhance
seepage when the water table dropped (as is also seen in Iran).
From there the water was used to irrigate fields.
There is another instructive structure located at the Kharga Oasis.
A well which apparently dried up was improved by driving a side
shaft through the easily penetrated sandstone (presumably in the
direction of greatest water seepage) into the hill of Ayn-Manâwîr
to allow collection of additional water. After this side shaft had
been extended, another vertical shaft was driven to intersect the
side shaft. Side chambers were built and holes bored into the
rock—presumably at points where water seeped from the rocks—are
David Mattingley reports foggara extending
for hundreds of miles in the Garamantes
area near Jarma in Libya: "The
channels were generally very narrow - less than 2 feet wide and 5
high - but some were several miles long, and in total some 600
foggara extended for hundreds of miles underground.
Exit of a foggara
channels were dug out and maintained using a series of
regularly-spaced vertical shafts, one every 30 feet or so, 100,000
in total, averaging 30 feet in depth, but sometimes reaching 130."
("The 153 Club Newsletter"
, July 2007 No. 112,
pp. 14-19; reprinted from Current world
The foggara water management system in Tunisia, used to create
oases, is similar to that of the Iranian qanat. The foggara is dug
into the foothills of a fairly steep mountain range such as the
eastern ranges of the Atlas
. Rainfall in the mountains enters the aquifer and
moves toward the Saharan region to the south. The foggara, 1 to
3 km in length, penetrates the aquifer and collects water.
Families maintain the foggara and own the land it irrigates over a
ten meter wide, with width only by the size of plot that the
available water will irrigate.
(designated foggaras in Algeria) are the source of water for irrigation at large
oases like that at Gourara.
The foggaras are also found at
(an area of Adrar 200 km from
Gourara). The length of the foggaras in this region is estimated to
be thousands of kilometers.
Although sources suggest that the foggaras may have been in use as
early as 200 AD, they were clearly in use by the 11th century after
the Arabs took possession of the oases in the 10th century and the
residents embraced Islam.
The water is metered to the various users through the use of
which meter flow to the
various canals, each for a separate user.
The humidity of the oases is also used to supplement the water
supply to the foggara. The temperature gradient in the vertical
shafts causes air to rise by natural convection, causing a draft to
enter the foggara. The moist air of the agricultural area is drawn
into the foggara in the opposite direction to the water run-off. In
the foggara it condenses on the tunnel walls and the air passed out
of the vertical shafts. This condensed moisture is available for
In southern Morocco the qanat (locally khettara
) is also
the margins of the Sahara Desert, the isolated oases of the
River valley and Tafilalt have relied on qanat water for
irrigation since the late-14th century.
In Marrakech and the
Haouz plain the qanats have been abandoned since the early 1970s as
they've dried; in the Tafilaft area half of the 400 khettaras are
still in use. The Hassan Adahkil Dam's impact on local water tables
is said to be one of the many reasons given for the loss of half of
The black berbers (haratin
) of the
south were the hereditary class of qanat diggers in Morocco who
build and repair these systems. Their work was hazardous.
have preserved in Armenia in the community of Shvanidzor, in the southern province of Syunik, bordering
Qanats are named kahrezes
in Armenian. There are 5
kahrezes in Shvanidzor. Four of them were constructed in XII-XIVc,
even before the village was founded. The fifth kahrez was
constructed in 2005. Potable water runs through I, II and V
kahrezs. Kahrez III and IV are in quite poor condition. In summer,
especially in July and August, the amount of water reaches its
minimum, creating critical situation in the water supply system.
Still, kahrezes are the main source of potable and irrigation water
for the community.
m long Claudius Tunnel, meant for draining
the largest Italian inland water, Fucine Lake, was constructed in the qanat technique.
featured shafts up to 122 m deep. The entire ancient town of Palermo in Sicily has been built over
a huge qanat system built during the Arab period (827–1072).
Many of the qanat are now mapped and some can be visited. An
interesting building is the famous Scirocco room, which has an air
refreshing system using the flux of waters of a qanat and a "wind
tower", a structure able to catch the wind and direct it into the
Raschpëtzer near Helmsange in southern Luxembourg is a particularly well preserved example of a
It is probably the
most extensive system of its kind north of the Alps
. To date some 330 m of the total tunnel length of
600 m have been explored. Thirteen of the 20 to 25 shafts have been
investigated. The qanat appears to have provided water for
a large Roman villa on the slopes of the
It was built during the Gallo-Roman
period, probably around the year 150
and functioned for about 120 years thereafter.
still many examples of galeria or qanat systems in
Spain, most likely brought to the area by the Moors during their occupation of the Iberian
peninsula. Turrillas in Andalusia on the north facing slopes of the Sierra de Alhamilla has evidence of a
qanat system. Granada is another site with an extensive qanat
Qanats in the Americas can be found in the Atacama regions of Peru,
and Chile at Nazca and Pica. The Spanish introduced qanats into
Mexico in 1520 AD.
- Ahmad Y
Hassan, Transfer Of Islamic Technology To The West, Part
Ii: Transmission Of Islamic Engineering
- Qanat, Kariz and Khattara: Traditional Water Systems in the
Middle East - By Peter Beaumont, Michael E. Bonine, Keith
- The Traditional Crafts of Persia: Their Development and
Technology by Hans E. Wulff
- Wessels, K. (2000), Renovating Qanats in a changing world, a
case study in Syria, paper presented to the International Syposuim
on Qanats, May 2000, Yazd, Iran, quoted in: WaterHistory.org:Qanats, accessed on October 25,
- Yakchal: Ancient Refrigerators
- Yakchal: Ancient Refrigerators
- James A. Michener, Caravans, New York: Random
House, 1963 Ch. 8
- Michael M. Phillips Learning a Hard History Lesson in 'Talibanistan':To
Accommodate New Troops, the U.S. Military Expanded a Base and
Inadvertently Disrupted Ancient Afghan Canals, The Wall
Street Journal, May 14 2009
- Oasis at Turpan in northwestern China uses water provided by karez.
- Of these only 25,000 remain in use as of 1980.
- UNESCO: Water shortage fueling displacement of people in
northern Iraq, UNESCO study finds, October 2009, accessed on
October 25, 2009
- History from Waterhistory.org
- UNESCO: Aflaj
Irrigation Systems of Oman, accessed on October 25, 2009
- Michel Wuttmann, "The Qanats of 'Ayn-Manâwîr, Kharga Oasis,
Egypt", in Jasr 2001, p. 1 (pdf).
- "Water: symbolism and culture"
- An excellent UNESCO article with numerous clear
photographs showing the Foggara in Algeria
- Article titled Etymological Conduit to the Land of Qanat
by Dr. V. Sankaran Nair, 2004
- Grewe, Klaus: Licht am Ende des Tunnels. Planung und
Trassierung im antiken Tunnelbau, Mainz 1998, ISBN
- Pierre Kayser and Guy Waringo: L’aqueduc souterrain
des Raschpëtzer, un monument antique de l’art de l’ingénieur au
Luxembourg. Retrieved 2 December 2007.
- Water supplies in Granada - A good visible
qanat can be seen to the west of the church of San Lorenzo, a
suburb of Segovia, irrigating what were huertas (market
- Libyan web site on qanats
- WaterHistory.org Article on Karez in Turpan, Xinjiang,
- World Wildlife Fund Editorial on Karez in
- Useful information on Qanat provided by Farzad
Kohandel, in arabic) and in english
- Information on Qanats (includes photo of access
shafts from above)
- Site includes discussion of use of qanats in
Center on Qanats and Historic Hydraulic Structures
- The origin and spread of qanats in the Old
World - by PW English, in Proceedings of the American
Philosophical Society Volume 112, Number 3 June 21, 1968.
- The art and science of water, in Saudi Aramco
- Turpan, China
- Carlo Trabia: “Kanats of Sicily”, in: Best of Sicily
Magazine, March 2005, with Photo
-  A visit inside a qanat in