Traditional methods of irrigation in Iran

The traditional methods of irrigation Persians ( abyari in Persan) played a big role in civilization and the history Perse because of aridity of the territory of the Iran. Indeed, only the littoral of the Caspian Sea is not classified like arid or semi-arid and only the Khorasan, the Azerbaïdjan and the Kurdistan practice a Agriculture not irrigated. The Irrigation thus always played a big role not only to develop the agricultural productions, but also, to facilitate the firing plant of populations vaster.

History of the irrigation in Iran

The origins and the developments in the first technologies of irrigation are not known. According to the archaeological discoveries which were made, the first traces of systematic irrigation appear in Southeast Asia at the 6th millenium before our era, on the slopes of the mounts Zagros, territories currently located in Iraq and in the Khuzestan. From this time and until the 1st millenium before J.C., the irrigation was spread on the Iranian plate and in all the Iran. These processes of irrigation were encouraged by the Achéménides. One of these techniques of irrigation, known under the name of Qanat was spread with Oman and in the south-east of the Arabia towards the end of this same period, then, later with the Islamic conquest, in Central Asia and of the southern, in North Africa and Spain.

There no was determining technological change until the introduction of the Pompe S diesel, drillings and the stoppings of Reinforced concrete in the middle of the 20th century, at which time all these systems, traditional or modern, started and always continue to coexist in Iran.

Resources and technologies

On a total current territory of a little less than 165 million hectares, 16 million is arable lands and 7,65 million is irrigated. The water of irrigation comes from rivers, sources, well and the Qanat S . There do not exist statistics as for the distribution of each source of irrigation, but it is estimated that the rivers count for a half and the wells and qanats for the other, the share coming from the wells being in increase.

There is about thirty years, before the construction of dam and the mechanization and motorization of the pumps, the qanats represented surely half of the total.

The flow of the rivers, on the Iranian plate as in the majority of the country, varies largely according to the season. The flow of the Karoun, for example, has recorded maxima in April of 520.000 m ³ /s whereas the minimum (low water level) recorded in October is of 60.000 m ³ /s. This variation presents and presented an main issue for the systems design of irrigation.

Irrigation of catchment area

This technique, which consists in diverting the flow of the water of a river towards the adjacent grounds, is one of most rudimentary which is. It requires only one attention and a minimum investment, and it is that which was very important in the history of the valley of the the Nile in Egypt. The time during which the rising could be used is lengthened by associating a primitive stopping (stones, wood and branches, mud) to divert water towards the adjacent grounds, stopping which was destroyed at the time of the following rising.

Stoppings and band

The Achéménides and the Parthes developed the systems of irrigation by stoppings, and the Sassanides enormously sophisticated it while making use of cut stones and mortar containing of the iron parts. Most famous of the stoppings sassanides is that of Shadorvân, built by the king Shapur Ier on the Karoun with the assistance of prisoners captured at the time of his victory over the Valérien Roman Emperor in 260 av JC. The Khâju bridge, built at the time of Shah Abbas II and always upright with Esfahan on the Zayandeh rud has a similar structure, with valves making it possible to control the flow of water and providing a point of permanent passage on the river.

This technique used on the long run, decreases the productivity of the irrigated grounds, because the course of the river deposits rock salt (salt, gypsum and carbonate of calcium) which penetrate the ground, there precipitate and return it too saltworks to be cultivated. The current stoppings envisage systems of more important drainage in order to cure this problem.

Another similar technology is the band or retaining tank, which was used since at least as a long time as the diversion of the rivers and which was very important in the history of the occupation of the Iranian plate.

The band is a structure of stone or ground built in a system of irrigation in order to retain water so that the impurities and salts settle before making use of it for the irrigation of the arable lands. This technique certainly is not any more used intensively at the national level but remains important in some populated mountainous districts of nomads of the Balouchistan and in other arid districts of the Khorasan, where they make it possible to cultivate melons.

Well

The date of the first use of the well is not known. The archeologists discovered that they were used with fine servants in the valley of the Indus at 3rd front millenium JC, and there at that time exist former traces in Mésopotamie. It is probable that they were used in order to recover subterranean water in the south-west of Asia since the first times of the settlement of this area. Without mechanization, the wells have only little utility for the irrigation, since the efforts made to go up water do nothing but increase with the depth of the well.

The traditional techniques to go up water are the shadof , a long stick with a basket on a side and a counterweight of the other, the gâvchâh , in which one or two animals reassembles the basket using a drawn cord on the adjacent ground. Goatskin bottles being able to contain 10 to 60 liters were generally employed in these methods. This type of well was important particularly in the south of the Iran, in the coastal plain of the Persian Gulf in the north of Bandar Abbas and in the depression of Jaz Moryan with the Balouchistan.

Qanats

Distribution of water

The extraction and the availability of water surface would not serve if there did not exist an organization making it possible to gather water, as knowing which uses it, when and for which needs. The quantity of water can be tiny in the case of the traditional wells or of a qanat deriving a source not very important and it can be a very large in the case of large river or of an important stopping.

When the flow is not very important, extracted water can be stored in a basin before being redistributed in the neighbouring grounds by a system of irrigation of the cultures. The losses due to the escapes and the evaporation along the system can go up to 50%. For this reason, the grounds closest to the source of water have the most value, because water is there of better quality and that they can be cultivated several years of continuation.

The distribution of water is done on the basis of time, according to the duration during which a particular piece is cultivated. Attributions take account of the seasons and evaporation in order to most equitably distribute possible the losses between all the farmers.

When the quantity of water available was very important and relatively fine measurements, a known VIP under the name of mirâb (c.à.c amir-e âb , the “commander of water”) was named in order to supervise the system. This character could also be known under the name of âbyâr .

According to the ic law Islam, water cannot be bought nor sold. However, the channels and other means of distribution can be prone to commercial transactions. The tariffs depend enormously on the flow, the type of system, the ground, the dominant culture and other economic aspects and social. The Islamic law provides the general framework in which these transactions can take place, and the local practices bring additional rules and practices. In general, when two communities or more share the same source, the community upstream takes precedence over the community downstream. An example is provided by it by the system of redistribution of the water of the Zayandeh rud in the basin of Esfahan.

Irrigation and company

The various situations which developed starting from the various solutions imagined to satisfy the requirements in irrigation for the grounds require all a certain degree of Coopération between the farmers. The co-operation is indeed necessary in order to join together all the investment and the Labor necessary for the construction and the maintenance of the system. The structure of the social relations varies with time, and this variation affects the co-operation necessary to the system maintenance of irrigation.

It appears that the colonization of the Iranian plate did not only depend on the construction of the qanats but also of the economic stability and social which makes possible the co-operation during several generations. The fact that the Achéménides were the first required this safety makes it possible to validate the assumption that they were responsible for the aspect that revêt the distribution of the hearths of settlement in Iran.

In addition to the role of the irrigation in the Iranian history, its trace can be seen in the morphology of the zones occupied by the man and felt in the literature and the art.

The settlement of the urban hearths resembles an irregular grid, which corresponds to the old channels making it possible to deliver water. Moreover, the zones gathering the elite was rather upstream, because water quality and its availability there were better (cf above)

Orchard S were located upstream, and are connected to tradition of garden Persan, which creates in each village, in complete contrast with the arid medium which surrounds it, a green environment which is symbolically dependant, in the poetic tradition of Iran, with the concept of Paradis.

References

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