There is controversy on the origin of the word "qanat" among the etymologists. Some consider it a Persian word that has changed into the present pronunciation. They believe that the word "qanat" originated from the word "Kane" which means digging in Persian. In contrast to this theory, some consider an Arabic Origin for the word qanat, since its plural form is qanawat from which the English world canal has come. Another name widely used for qanat is "Kariz" or "Karez" that is originally Persian, meaning "Straw Pouring"
In the countries benefiting from qanats, different terms are applied to this hydraulic system. (F.J.Hum Lum, 1965), (P.Beaumont, M. Bonine, 1989), (Aghasi, Safinejad, 2000). There are more than 27 terms for qanat, being used in these countries:
"Qanat" and "Kariz" in Iran, "Falaj" pl "Aflaj" in Oman, "Kariz" or "Karez" in Afghanistan, Pakistan, Azerbaijan and Turkmenistan, "Ain" in Saudi Arabia, "Kahriz" in Iraq, "Kanerjing" in China, "Foggara" in Algeria, "Khattara" or "Khettara" and "Rhettaras" in Morocco, "Galleria" in the Spain, "Qanat Romoni" in Syria and Jordan, "Foggara" and "Khettara" and "Iffeli" in North Africa, "Galerias" in the Canary Islands, "Mambo" in Japan, "Inguttati" in Sicily. Some other terms used for qanats are as follows: Ghundat, Kona, Kunut, Kanat, Khad, Konait, Khriga, Fokkara, etc.
Figure 1- Qanat equivalent terms
Geographical distribution of qanats
The arid and semi-arid regions of the world, whose rainfall shortage does not allow any permanent surface streams, but enjoying rich groundwater resources, have had a good potential to house the system of qanat. So, the system of qanat could be introduced and spread rapidly across such regions.
Figure 2 - Geographical distribution of qanat
Iwao Kobori (I. Kobori, 1964) believes that the qanat system, in all probability, developed in ancient Persia some 2500 years ago and then spread to Afghanistan and eventually along the Silk road as far east as China, as well as by Arabic cultures to the far west including Morocco and Spain.
According to Goblot (H. Goblot, 1979), qanats originated in the northwest of present Iran, dating back to 600-800 B.C. In 525 BC qanats were introduced to the southern coast of the Persian Gulf and then in 500 BC to Egypt, in 750 AD to Spain, in 850 AD to Southern Algeria, in 1520 AD to Mexico & Los Angeles, in 1540 AD to Pica in Chile and in 1780 AD to Turfan (NW Chins .
Also some scholars go far back in antiquity regarding the qanats of Syria. They have maintained that the Hailan-Aleppo qanat, a 12-km long subterranean channel which functioned until the early part of this century, is coeval with the Aramaeans and their fortress at Aleppo (13th century B.C.) However, this is highly unlikely as the best evidence (archaeological and written accounts) suggests that qanat irrigation was first invented in the Armenian-Persian region about 600-800 B.C. (Lightfoot Dale R. 1997).
Jordanians today refer to qanats as "Roman canals", or qanat Romani (kaneh Romani in northern Jordan). Most scholars believe that Jordan’s qanats were built by the Romans and used by the Byzantines from the 1st century B.C. to the 7th century A.D. (Lightfoot Dale R. 1996).
The origin and geographical diffusion of qanats have caught the attention of many scholars, and there is some valuable research on this issue. For example, Haupt a German researcher has studied a qanat system in the area of Lake Van in Turkey (Haupt Lehmann, 1925), and then Weisgerber conducted research on the history of qanats in Oman (Weisgerber Gerd, 2003). Chauveau has studied qanats in the oasis of Kharagha’ in Egypt from archeological point of view (Chauveau Michel, 2001), and Salvini has done some research on the historic hydraulic structures in Urartu (Salvini Mirjo, 2001). Also, there are some scientific reports on the qanats of Oman and Iran, written by Boucharlat, the French archeologist (Boucharlat Remy, 2001). Another scholar, Briant, has scrutinized the text of Polibius on the qanats of Iran (Briant Pierre, 2001). An Iranian historian named Zohreh Cheraghi has provided a valuable anthology on the research conducted on qanat history and its geographical diffusion up to the present in her PhD thesis (Cheraghi Zohreh, 2010).
The system of the qanat spreads out between the latitudes 15° and 45°N, and this technique can be found even in such rainy regions as Germany. According to some studies, many of the countries between the abovementioned latitudes enjoyed the system of qanat and some of them still profit from this technique: for example, one can mention such Asian countries as Japan, China, Afghanistan, Pakistan (Baluchistan), Iraq (Kurdistan), Oman, Saudi Arabia, Iran, Syria and Azerbaijan (Nakhchivan).
Also, most of the North African countries like Egypt, Libya, Tunisia, Algeria, and Morocco enjoyed the benefit of qanats some of which are still active. In the Canary Islands a considerable number of qanats has been reported. In Europe including Spain, Greece, Germany and Sicily there existed qanats some of which were used as a subterranean canal just to convey water from a surface source to the desired place.
In the new world, the qanat has not played a vital role in supplying water, but some running qanats have been seen in Mexico (Parras), Peru (Nasca), Chile (Pica), Hawaii (Honolulu), USA (California and Los Angeles).
Historical evolution of qanats in Iran
In the course of Iranian history, the qanat has had many ups and downs. Sometimes the qanats as well as the qanat constructers were supported and encouraged by the government, and sometimes were deserted. Even when the qanats were destroyed for some military purpose, the qanat would start flourishing as soon as the political situation got stable. The risks that threaten qanats today differ from those in the past. In other words, in the past political and military crises had a negative impact on qanats; however, the qanats could recover as soon as the crisis was over. But the present risks are something else, and more destructive in the long term. The present risks are acting environmentally, so it is not so easy to tackle them. Therefore, it is essential for the governments and nations throughout the world to think more about introducing new legislation on the protection of groundwater resources against any kind of over -exploitation.
Qanat civilization is rooted in this ancient hydraulic structure. Over the past 3000 years, the system of qanat has underlain many technological, social, moral, economical and legal principles that have formed an important part of the Iranian culture. These principles evolved into the present state by being passed from generation to generation. The present generation should build on these principles, behind which there are three thousand years of history, not to forget about them.
In order to review the situation of qanats in the course of Iranian history, this part of the report explores some documents on qanats, from the first historical records to the present ones. To do so, two periods – before and after Islam – have been examined. In terms of each period we try to review the situation of qanats keeping pace with the history of kings and governments.
First of all, it seems necessary to look at the geographical and climatological conditions of Iran, for the natural infrastructure had an important role in creating and developing the qanat systems.
Suffice it to say, Iran has a variable but, In general, arid climate in which most of the relatively scant annual precipitation falls from October through April. In most of the country, yearly precipitation averages 250 millimeters or less. The major exceptions are the higher mountains of the Zagros and the Caspian coastal plain, where precipitation averages at least 500 millimeters annually. In the western part of the Caspian, rainfall exceeds 1000 millimeters annually and is distributed relatively evenly throughout the year. This contrasts with some basins of the Central Plateau that receive 100 millimeters or less of precipitation annually.
It is Henry Goblot who explores the genesis of this technology for the first time. He argues in his book entitled “Qanat; a Technique for Obtaining Water” that during the early first millennium before Christ, for the first time some small tribal groups gradually began immigrating to the Iranian plateau where there was less precipitation than in the territories they came from. They came from somewhere with many surface streams, so their agricultural techniques required more water than was available in the Iranian plateau. So they had no option but to fasten their hopes on the rivers and springs that originated in the mountains. They faced two barriers; the first was the seasonal rivers which had no water during the dry and hot seasons. The second was the springs that drained shallow groundwater and fell dry during the hot season. But they noticed some permanent runoff flowing through the tunnels excavated by the Acadian miners who were in search of copper. These farmers established a relationship with the miners and asked them to dig more tunnels in order to supply more water. The miners accepted to do that, because there was no technical difficulty for them in constructing more canals. In this manner, the ancient Iranians made use of the water that the miners wished to get rid of it, and founded a basic system named qanat to supply the required water to their farm lands. According to Goblot, this innovation took place in Urartu and later was introduced to the neighboring areas like the Zagros Mountains.
According to an inscription left by Sargon II the king of Assyria, In 714 BC he invaded the city of Uhlu lying in the northwest of Uroomiye lake that lay in the territory of the Urartu empire, and then he noticed that the occupied area enjoyed a very rich vegetation even though there was no river running across it. So he managed to discover the reason why the area could stay green, and realized that there were some qanats behind the matter. In fact it was Ursa the king of the region who had rescued the people from thirst and turned Uhlu into a prosperous and green land. Goblot believes that the influence of the Medians and Achaemenians made the technology of qanat spread from Urartu (in the western north of Iran and near the present border between Iran and Turkey) to all over the Iranian plateau.
Although Goblot's theory may be valid in Urartu or neighboring regions, we believe that we should be more realistic toward the invention of qanat. It is more likely that the first qanats were built in the central plateau of Iran at the mountain bases or along the valleys, though we do not rule out the possibility of construction of qanats outside of this region for example in Oman or Urartu independently. But it is hard to accept the theory that the qanat was first invented by the copper miners in Urartu and then introduced to the Iranian plateau and used by the farmers who lived some 1500 kilometers away from its origin. Not only in the past, but also at present, the immediate reaction of any farmer is to dig into a spring when its water dwindles. In the mountainous region surrounding the Iranian desert there were many natural springs which supplied water to the small communities who lived there. In the wake of climate change, the precipitation reduced and accordingly many of the springs dried up or just trickled. In this situation the immediate reaction of the people might be to dig the same springs to track the water, and after a while they ended up building a long tunnel with some shaft wells through which they could better haul the debris to the surface. In fact, we consider that the natural springs led the people to construct the first qanats, and it is very likely that an ancient man would be inspired by a trickling spring to burrow back to get closer to the source of water. Probably that was how the system of qanat came into existence, probably in several regions simultaneously. Hasanalian who has conducted much research on Sialk has come to the conclusion that the spring of Fin which once provided this ancient settlement with water was later manipulated and turned into a qanat (Hasanalian Davood, 2006). Even a few years ago we witnessed this process in an off the beaten path village in southern Khorasan. In this village there was a natural spring with a discharge of about 3 liters per second. After a drought broke out some 15 years ago, the water of this spring dramatically decreased and as a result the villagers made up their mind to deepen the spring to reach water again. They dug the spring horizontally up to 30 meters and every year they extended this tunnel to keep the discharge steady. After 20 years that spring was turned into a qanat with two shaft wells. This scenario can be seen beside the theory that the miners of Urartu invented the qanat as a byproduct, and could be repeated wherever enjoyed suitable conditions for qanats were present. Who knows how or even whether the farmers in the central Iran came in contact with those miners in Urartu and how they learnt this technique and how they brought it to the central Iran?
 - This name reflects a tradition of water division according to which some straw was poured in the qanat water while distributing water among the farmers, to specify how much water belongs to a particular shareholder.
 Strictly speaking Urartu is the Assyrian term for a geographical region, while the "Kingdom of Urartu" or the "Biainili lands" are the Iron Age state that arose in that region. That a distinction should be made between the geographical and the political entity was already pointed out by König. The landscape corresponds to the mountainous plateau between Asia Minor, Mesopotamia, and the Caucasus mountains, later known as the Armenian Highlands. The kingdom rose to power in the mid 9th century BC and was conquered by Media in the early 6th century BC. (http://en.wikipedia.org/wiki/Urartu)
 Sialk is a large ancient archeological site near the city of Kashan, in central Iran, tucked away in the suburbs, close to Fin Garden. The culture that inhabited this area has been linked to the Zayandeh Rud Civilization. What remains of the 5000-year-old ziggurat of Sialk is not in a favorable condition like many other ancient ruins in Iran. At the site, there are actually two structures (necropoli) Sialk situated several hundred feet from each other. The three platforms of the larger ziggurat, however, still remain in place. Not much remains of the smaller structure. The Louver has also excavated a cemetery near the structures that has been dated as far back as 7,500 years. (http://en.wikipedia.org/wiki/Tappeh_Sialk) – too much detail for a footnote – shorten if possible