Étiquette : Aqueduct
By Karel Vereycken, July 2021.
By Karel Vereycken, July 2021.
At a time when old diseases make their return and new ones emerge worldwide, the tragic vulnerability of much of humanity poses an immense challenge.
One wonders whether to laugh or cry when international authorities trumpet without further clarification that to stop the Covid-19 pandemic, “all you have to do” is “wash your hands with soap and water”!
They forget one small detail: 3 billion people do not have facilities to wash their hands at home and 1.4 billion have no access to either water or soap!
Yet, since the dawn of time, mankind has demonstrated its capacity to mobilize its creative genius to make water available in the most remote places.
Here is a short presentation of a marvel of such human genius, the “qanâts”, an underground water conveyance system dating from the Iron Age. Probably of Egyptian origin, it was deployed on a large scale in Persia from the beginning of the 1st millennium BC.
The qanât or underground aqueduct
Sometimes called “horizontal drilling”, the qanât is an underground aqueduct employed to draw water from a water table and convey it by simple gravitational effect to urban settlements and farmland. The word qanât is an old Semitic word, probably Accadian, derived from a root qanat (reed) from which come canna and canal.
This “drainage gallery”, cut into the rock or built by man, is certainly one of the earliest and most ingenious inventions for irrigation in arid and semi-arid regions. The technique offers a significant advantage: by conveying water through an underground conduit, contrary to open air canals, not a single drop of water is wasted by evaporation.
Oases’ are NOT natural phenomena. All known oases are man-made. It is the qanât technique that allows man, in a given geographic configuration, to create oases in the middle of the desert, when a water table is close enough to the ground level or at a site close to the bed of a river lost in the sands of the desert.
Copied and expanded by the Romans, the qanât technique was carried across the Atlantic to the New World by the Spaniards, where many such underground canals still function in Peru and Chile. In fact, there are even Persian qanâts in western Mexico.
While today this three thousand year old technique may not be appropriate everywhere to solve current water scarcity problems in arid and semi-arid regions, it has much to inspire us as a demonstration of human genius at its best, that is, capable of doing a lot with a little.
The oases of Egypt
Today, 95% of the Egyptian population prospers on only 5% of its territory, mainly around the Nile delta. Hence, from the earliest days of Egyptian civilization, irrigation and water storage techniques for the Nile floods were developed in order to conserve this silty, nutrient-rich water for use throughout the year.
The river water was diverted and transported by canals to the fields by gravity. Since water from the Nile did not reach the oases, the Egyptians used the gushing water from the springs, which came from the large aquifer reserves of the western desert, and conveyed it to the fields by irrigation canals.
One of the fruits of this attempt to “conquer the desert” was a sustained habitation of the Dakhleh oasis throughout the Pharaonic period, explicable not only by a commercial interest on the part of the Egyptian state, but also by the new agricultural perspectives it offered.
Closer to us in time, the Qanât Fir’aun (The Watercourse of the Pharaoh) also known as the aqueduct of Gadara, a city today in Jordan. As far as we know, this 170 km long structure, depending on the geography, combines several bridge-aqueducts (of the same type as the Gard aqueduct in France) and 106 km of underground canals using the Persian qanât technique. It is not only the longest but also the most sophisticated aqueduct of antiquity, and the fruit of a years of hydraulic engineering.
In reality, the Romans, hiring persian water experts, did nothing more than terminate in the 2nd century an ancient project designed to supply water to the “Decapolis”, a collaborative group of ten cities founded by Greek and Macedonian settlers under the Seleucid king Antiochos III (223 – 187 BC), one of the successors of Alexander the Great.
These ten cities were located on the eastern border of the Roman Empire (now in Syria, Jordan and Israel), united by language, culture and political status, each with a degree of autonomy and self-rule. Its capital, Gadara, was home to more than 50,000 people and known for its cosmopolitan atmosphere, its own university attracting scholars, writers, artists, philosophers and poets. But this rich city lacked something existential : an abundance of water.
The Gadara qanat made the difference. “In the capital alone, there were thousands of fountains, watering holes and baths. Wealthy senators cooled themselves in private pools and decorated their gardens with cooling caves. The result was a record daily consumption of more than 500 liters of water per capita,” explains Matthias Schulz, author of a report on the aqueduct in Spiegel Online.
We all admire the roman aqueducts. But few of us are aware that the Romans only adapted the technique of the qanâts developed much earlier in Persia.
Indeed, it was under the Achaemenid Empire (around 559 – 330 BC.), that this technique spread slowly from Persia to the east and the west. Many qanâts can be found in North Africa (Morocco, Algeria, Libya), in the South East Asia (Iran, Oman, Iraq) and further east, in Central Asia, from Afghanistan to China (Xinjiang), via India.
The development of these “draining galleries” is attested in different regions of the world under various names: qanât and kareez in Iran, Syria and Egypt, kariz, kehriz in Pakistan and Afghanistan, aflaj in Oman, galeria in Spain, kahn in Balochistan, kanerjing in China, foggara in North Africa, khettara in Morocco, ngruttati in Sicily, bottini of Siena, etc.
Historically, the majority of the populations of Iran and other arid regions of Asia or North Africa depended on the water provided by the qanâts; their construction lifted entire areas to a higher “economic platform”, made deserts habitable and opened new land for agriculture. The map of demographic expansion followed the trail of the development of this new higher platform.
In his article « Du rythme naturel au rythme humain : vie et mort d’une technique traditionnelle, le qanât » (From natural rhythm to human rhythm: the life and death of a traditional technique, the qanât), Pierre Lombard, a researcher at the French CNRS, points out that this is not an artisanal and marginal process:
“Until a few years ago, the importance of the ancestral technique of qanât was sometimes ignored in Central Asia, Iran, Syria, and even in the countries of the Arabian Peninsula. For example, the Public Authority for Water Resources of the Sultanate of Oman estimated in 1982 that all the qanâts still in operation conveyed more than 70 % of the total water used in that country and irrigated nearly 55% of the cereal lands. Oman was still one of the few states in the Middle East to maintain and sometimes even develop its qanât network; this situation, apart from its longevity, does not appear to be exceptional. If one turns to the edges of the Iranian Plateau, one can note with Wulff (1968) the obvious discrepancy between the relative aridity of this area (between 100 and 250 mm of annual precipitation) and its non-negligible agricultural production, and explain it by one of the densest networks of qanâts in the Middle East. It can also be recalled that until the construction of the Karaj dam in the early 1960s, the two million inhabitants of Tehran at that time consumed exclusively the water brought from the Elbourz foothills by several dozen regularly maintained qanâts. Finally, we can mention the case of some major oases in the Near and Middle East (Kharga in Egypt, Layla in Saudi Arabia, Al Ain in the United Arab Emirates, etc.) or in Central Asia (Turfan, in Chinese Turkestan) that owe their vast development, if not their very existence, to this remarkable technique.”
On the website ArchéOrient, the French archaeologist Rémy Boucharlat, Director of Research Emeritus at the CNRS, an Iran expert, explains:
“Whatever the origin of the water, deep or not, the technique of construction of the gallery is the same. First, the issue is to identify the presence of water, either its going underground near a river, or the presence of a water table under a foothill, which requires the science and experience of specialists. A motherwell will be dug to reach the top of the water table, indicating at which depth the [horizontal] gallery should be drilled. It’s slope must be very small, less than 2‰, so that the flow of water is calm and regular, and conduct the water gradually to the surface area, according to a gradient much lower than the slope of the foothill.
“The gallery is then dug, not starting from the mother well because it would be immediately flooded, but from downstream, from the point of arrival. The conduct is first dug in an open trench, then covered, and finally gradually sinks into the ground in a tunnel. For the evacuation of soil and ventilation during excavation, as well as to identify the direction of the gallery, shafts are dug from the surface at regular intervals, between 5 and 30 m depending on the nature of the land ».
In April 1973, Lyndon LaRouche’s friend, the French-Iranian professor and historian Aly Mazahéri (1914-1991), published his translation from Arab into French of “The Civilization of Hidden Waters”, a treatise on the exploitation of underground waters composed in the year 1017 by the Persian hydrologist Mohammed Al-Karaji, who lived in Baghdad. (Translated in English in 2011)
After an introduction and general considerations on geography, natural phenomena, the water cycle, the study of terrain and the instruments of the hydrologist, Al-Karaji gives a highly precise technical outline of the construction and maintenance of qanâts, as well as legal considerations respecting their management and maintenance.
In his introduction to Al-Karji’s treatise, Professor Mazaheri emphasizes the role of the Iranian city of Merv (now in Turkmenistan). This ancient city, he says, was part of
“the long series of oases extending at the foot of the northern slope of the Iranian plateau, from the Caspian to the first foothills of the Pamirs. There, between the geological extension of the Caspian towards the East, there is a strip of arable land, more or less wide, but very fertile. Now, to exploit it, a lot of ingenuity is needed: where, for example in Merv, a big river, such as the Marghab, coming from the glaciers of the central East-Iranian massif, crosses the chain, it is necessary to establish dams, above the strip of arable land, without which, the ‘river’, divided into several dozens of arms, rushes under the sands. Elsewhere, and it is almost all along the northern slope of the chain, one can create artificial oases, by bringing the water by underground aqueducts.” (p. 44)
“The construction of dams and underground aqueducts are among the most interesting legacies of their (the ancient Persians) irrigation techniques (…) Long before Islam, the Persian hydrologists had built thousands of aqueducts, allowing the creation of hundreds of villages, dozens of cities previously unknown. And very often, even where there was a river, because of the insufficiency of this one, the hydronomists had brought to light many aqueducts allowing the extension of the culture and the development of the city. Naishabur was such a city. Under the Sassanids, and later under the Caliphs, an important network of aqueducts had been created there, so that the inhabitants could afford the luxury of owning a ‘’bathing room’ in the basement, at the level of the aqueduct serving the house.”
Let us recall that most Persian scholars, including the famous mathematician Al-Khwarizmi, not suffering from today’s hyper-specialization that tends to curb creative thinking, excelled in mathematics, geometry, astronomy and medicine as well as in hydrology.
Mazaheri confirms that this “civilization of underground waters” spread well beyond the Iranian borders:
“Already, under the [Umayyad] Caliph Hisham (723-42), Persian hydronomists built aqueducts between Damascus and Mecca (…) Later, Mecca suffering from lack of water, Zubayda, the wife of Hâroun Al-Rachîd, sent Persian hydronomists there who endowed the city with a large underground aqueduct. And each time the latter was silted up, a new team left Persia to restore the network: such repairs took place periodically under Al-Muqtadir (908-32), under Al-Qa’im (1031-1075), under Al-Naçir (1180-1226) and, at the beginning of the fourteenth century, under the Mongol prince Emir Tchoban. We would say the same of Medina and the stages on the pilgrimage route, between Baghdad and Mecca, wherever it was possible to do so, hydronomic works were undertaken and ‘underground aqueducts’ were created.
“Hydronomy is a highly demanding skill. To practice it, it is not enough to have mathematical knowledge: decadal calculus, algebra, trigonometry, etc., it is necessary to spend long hours in the galleries at the risk of dying by flooding, landslide or lack of air. It is necessary to have an ancestral instinct of ‘dowser’.”
The annual rainfall in Iran is 273 mm, which is less than one third of the world’s average annual precipitation.
The temporal and spatial distribution of precipitation is not uniform; about 75% occurs in a small area, mainly on the southern coast of the Caspian Sea, while the rest of the country does not receive sufficient rainfall. On the temporal scale, only 25% of the precipitation occurs during the plant growing season.
7,7 x the circonférence of the Earth
Still in use today in Iran, qanâts currently supply about 7.6 billion m3 of water, close to 15% of the country’s total water needs.
Considering that the average length of each qanât is 6 km in most parts of the country, the total length of the 30,000 qanât systems (potentially exploitable today) is about 310,800 km, which is about 7.7 times the circumference of the Earth or 6/7th of the Earth-Moon distance!
This shows the enormous amount of work and energy applied to build the qanâts. In fact, while more than 38,000 qanâts were in operation in Iran till 1966, its number dropped to 20,000 in 1998 and is currently estimated at 18,000. According to the Iranian daily Tehran Times, historically, over 120,000 qanat sites are documented.
Moreover, while in 1965, 30-50% of Iran’s total water needs were met by qanats, this figure has dropped to 15% in recent decades.
According to the Face Iran website:
“The water flow of qanâts is estimated between 500 and 750 cubic meters per second. As land aridity tends to vary according to the abundance of rains in each region, this quantity of water is used as a more or less important supplement. This makes it possible to use good land that would otherwise be barren. The importance of the impact on the desert can be summarized in one figure: about 3 million hectares. In seven centuries of hard work, the Dutch conquered 1.5 million hectares from the marshes or the sea. In three millennia, the Iranians have conquered twice as much on the desert.
Indeed, to each new qanât corresponded a new village, new lands. From where a new human group absorbed the demographic surplus. Little by little the Iranian landscape was constituted. At the end of the qanat, is the house of the chief, often with one floor. It is surrounded by the villagers’ houses, animal shelters, gardens and market gardens.
The distribution of land and the days of irrigation of the plots were regulated by the chief of the villages. Thus, a qanat imposed a solidarity between the inhabitants.”
If each qanât is “invented” and supervised by a mirab (dowser-hydrologist and discoverer), the realization of a qanât is a collective task that requires several months or years, even for medium-sized qanâts, not to mention works of record dimensions (a 300 m deep mother-well, a 70 km long gallery classified in 2016 as a World Heritage Site by UNESCO, in northeast Iran).
Each undertaking is carried out by a village or a group of villages. The absolute necessity of a collective investment in the infrastructure and its maintenance requires a higher notion of the common good, an indispensable complement to the notion of private property that rains and rivers do not take in account.
In the Maghreb, the management of water distributed by a khettara (the local name for qanâts) follows traditional distribution norms called “water rights”. Originally, the volume of water granted per user was proportional to the work contributed to build the khettara, translated into an irrigation time during which the beneficiary had access to the entire flow of the khettara for his fields. Even today, when the khettara has not dried up, this rule of the right to water persists and a share can be sold or bought. Because it is also necessary to take into account the surface area of the fields to be irrigated by each family.
The causes of the decline of the qanâts are numerous. Without endorsing the catastrophist theses of an anti-human ecology, it must be noted that in the face of the increasing urban population, the random construction of dams and the digging of deep wells equipped with electric pumps have disturbed and often depleted the aquifers and water tables.
A neoliberal ideology, falsely described as “modern”, also prefers the individualistic “manager” of a well to a collective management organized among neighbors and villages. A passive State authority has done the rest. In the absence of more thoughtful reflection on its future, the age-old system of qanâts is on the verge of extinction as a result.
In the meantime, the Iranian population has grown from 40 to over 82 million in 40 years. Instead of living off oil, the country is seeking to prosper through agriculture and industry. As a result, the need for water has increased substantially. To cope with rising demands, Iran is desalinating sea water at great cost. Its civilian nuclear program will be the key factor to provide water at a reasonable cost.
Beyond political and religious divisions, closer cooperation between all the countries in the region (Turkey, Syria, Iraq, Israel, Egypt, Jordan, etc.) with a perspective to improve, develop, manage and share water resources, will be beneficial to each and all.
Presented as an “Oasis Plan” and promoted for decades by the American thinker and economist Lyndon LaRouche, such a policy, translating word into action, is the only basis of a true peace policy.
- Remy Boucharlat, The falaj or qanât, a polycentric and multi-period invention, ArcheOrient – Le Blog, September 2015 ;
- Pierre Lombard, Du rythme naturel au rythme humain : vie et mort d’une technique traditionnelle, le qanat, Persée, 1991 ;
- Aly Mazaheri, La civilisation des eaux cachées, un traité de l’exploitation des eaux souterraines composé en 1017 par l’hydrologue perse Mohammed Al-Karaji, Persée, 1973 ;
- Hassan Ahmadi, Arash Malekian, Aliakbar Nazari Samani, The Qanat: A Living History in Iran, January 2010;
- Evelyne Ferron, Egyptians, Persians and Romans: the interests and stakes of the development of Egyptian oasis environments.
 The ten cities forming the Decapolis were: 1) Damascus in Syria, much further north, sometimes considered an honorary member of the Decapolis; 2) Philadelphia (Amman in Jordan); 3) Rhaphana (Capitolias, Bayt Ras in Jordan); 4) Scythopolis (Baysan or Beit-Shean in Israel), which is said to be its capital; It is the only city west of the Jordan River; 5) Gadara (Umm Qeis in Jordan); 6) Hippos (Hippus or Sussita, in Israel); 7) Dion (Tell al-Ashari in Syria); 8) Pella (Tabaqat Fahil in Jordan); 9) Gerasa (Jerash in Jordan) and 10) Canatha (Qanawat in Syria)