“ICAL 1/DT X Joint International Symposium with JAALS”

沙漠研究 21-2, 71 -73 (2011 )-Memorial Article-

Journal of Arid Land Studies

Qanat; an Ancient Technique for Adapting to New Climate Changes
Ali ASGHAR SEMSAR YAZDI*1)
Abstract: Global warming could have given rise to climate changes in many parts of the world to a large extent over the past decades.
Some regions are struck by destructive floods and unprecedented torrential downpour, whereas some other regions are in the grip ofsevere droughts. In some areas, the snow coverage is shrinking, resulting in a dramatic decrease in snow melt and the amount ofsurface streams. Permanent streams are turning into seasonal runoffs, and seasonal runoffs are drying out over time. In such areas thedemand for water is still on the rise, though their surface streams are diminishing. Therefore the residents of these areas resort toextracting groundwater which is more reliable to supply water to domestic and agricultural sectors. What may immediately flash
trough our mind is that pumped well is the best way to abstract groundwater, though our past experiences in arid and semi arid regionstell that such regions are subject to over-exploitation of groundwater and depletion of aquifer accordingly. In some arid zones,
groundwater used to be extracted by the system of Qanat over the past centuries without causing any drawdown in water table. Qanat
is a horizontal tunnel with a gentle slope that taps groundwater in an area more elevated than cultivated lands. Through this system
groundwater is drained out by the force of gravity, fully compatible with nature, without bringing about environmental backlashes.
This paper is aimed at explaining and recommending the traditional know how of Qanat to the regions which turning arid andbecoming short of surface streams. In fact if the regions which are affected by climate change use pumped wells in order tosupplement the water they need, they would go down the path of the present arid areas where over pumping has done a great damage
to groundwater reserves. Qanat never threatens groundwater resources and ensures sustainable utilization of groundwater, so it
deserves to be introduced to the areas in need of groundwater.
Key Words: Environment, Groundwater, Iwao Kobori, Qanat, Traditional knowledge

1. Preface
First of all we would like to express our great pity for thesad passing away of my great friend Prof. Iwao Kobori (Fig. 1).
He devoted over 50 years of his life to studying water supply inarid and semi arid regions. He also conducted many
researches on Qanat system, so that some call him "father ofQanat". May his soul rest in peace.
Figure 2 shows him at a ceremony in Yazd Iran, which
was held on 2nd October 2010 to appreciate and award him forhis half century of effort and study in the field of Qanat.

Fig. 1. Prof. Iwao Kobori.

2. Introduction
Many civilizations came into existence alongside greatrivers whereas a number who were short of surface run offs
had to find a solution to supply water (Kobori, 2005). They had
to bring groundwater on to the earth surface with a reliable
water flow and in a sustainable manner. This way wasnothing but Qanat which conveyed underground water to theearth surface just by the force of gravity. This water supply
system has bestowed life and prosperity on the inhabitants ofthe arid and semi-arid regions of the world (goblot, 1979).

Fig. 2. Special ceremony for Prof. Iwao Kobori, ICQHS: Yazd-IRIran.

* Corresponding Author: semsar@icqhs.org（Received August 25th, 2011; Accepted October 17th, 2011）

International Center on Qanats and Historic Hydraulic Structures (ICQHS), Po Box 89165-1553, Yazd, Iran. Tel: +98 351 825 83 93, Fax: 98 351 824 16 90.

1) Director, ICQHS: International Center on Qanats and Historic Hydraulic Structures (UNESCO Category II Center).

Fig. 3. Longitudinal section of a Qanat.

3. Qanat
3.1. Qanat Definition
Qanat is a gently sloping tunnel which drains thegroundwater from aquifer and leads it to the surface by using
gravity flow conditions (Fig. 3). In fact Qanat benefits fromthe differences between earth surface elevations to convey
water from upstream aquifer to the earth surface down slope.
To do so, Qanat enjoys a number of vertical shafts, asubterranean canal and an appearance (Bonine, 1989)(Lambton, 1989).
Qanat is a good example of human's harmony with nature.
The endeavors our ancestors used to make to build Qanats areamazing. Qanats paved the way for life and prosperity in thedesert, functioned like the veins of desert, and served as a basis
for the civilization of Qanat, civilization of hardworking,satisfaction, gentleness, patience and tolerance. A civilizationthat has ever never waged any war and invasion, and history isawash with examples that the oppressor rulers never originatedfrom this territory (Semsar Yazdi, 2010).
3.2. Qanat and Nature
There is a wealth of traditional knowledge in water
management of this technique that can lessen common errors
in policy, technical and managerial practices whileenlightening valuable hints to those in search of newapproaches. We just mention one of its characteristics which
is its harmony with nature.
Over the past decades, the pumped wells have played an
important role in undermining the underground water andaffecting the system of Qanat. However no one can deny thatin some regions the only option to exploit groundwater is todrill wells, but it should not be used as a pretext to replace theactive Qanat with the pumped wells in other regions (SemsarYazdi, 2007).
The over-exploitation of groundwater by pumps can cause
the water table to drawdown over 50 meters during half acentury (Fig. 4).
Under such condition, Qanat can not last long and would
vanish, the destiny many of the Qanats in the world aredoomed to.

Fig. 4. Drawdown of water table in Yazd plain from 1950 (Fig. a)
to 2000 (Fig. b) has caused Qanat annihilation.

The country of Iran possesses 37000 Qanats. These
Qanats are discharging 7 billion cubic meters water a year
without consuming any kind of fossil fuel or electricity(WRMO, 2005). If this water was to be discharged from thegroundwater resources by pumps, 800 Mega Watt electricity
would be needed. This electricity can be generated by a huge
power plant with its usual problems and environmental
pollution. Whereas the Qanat is supplying this amount ofwater without consuming fossil fuels and electricity whichbrings about environmental consequences.
Another advantage of Qanat is not to cause drawdown in
the water table. Given that the Qanat is built horizontally, it
can not extract water from less elevated spots of the aquifer.
Qanat is one of the rational groundwater exploitation methods,because (Semsar Yazdi, 2004):
・ It does not cause depletion in aquifer.
・ It does not consume fossil fuel or electricity, so it does notpollute environment.

4. Conclusion
Qanat is a system completely in harmony with nature, andenvironment friendly. So we suggest building Qanat in theareas whose groundwater level is high and the environmental
conditions favor Qanat construction, instead of drilling pumped
wells. Thus environment would not be deteriorated and thegroundwater reserves would be extracted in a rational manner.

We recommend the construction of Qanat to the regions
which turning arid and becoming short of surface streams. In
fact if the regions which are affected by climate change use
pumped wells in order to supplement the water they need, theywould go down the path of the present arid areas where overpumping has done a great damage to groundwater reserves.
Qanat never threatens groundwater resources and ensuressustainable utilization of groundwater, so it deserves to beintroduced to the areas in need of groundwater
The modern world shouldn't ignore the past experiences
which are in harmony with nature, and shouldn't be arrogant
over the new advances.
In terms of sustainable development, we can learn muchfrom water relics from whether structural or non-structural
point of view. The onus is on us to discover them andincorporate them into the new technologies.

References
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East and North Africa studies Press Ltd. England.

Goblot H. (1979): Les Qanats: Une technique d'acquisition del'eau. Mouton, Paris. 236p.
Kobori I. (2005): A History of Water Issues. United Nations
University, New York, 190p.
Lambton A. (1989): The origin, diffusion and functioning ofthe Qanat. Qanat, Kariz & Khattara, traditional water
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