Qanat

A qanat or kariz is a gently sloping underground channel to transport water from an aquifer or water well to surface for irrigation and drinking, acting as an underground aqueduct. This is an old system of water supply from a deep well with a series of vertical access shafts. The qanats still create a reliable supply of water for human settlements and irrigation in hot, arid, and semi-arid climates, but the value of this system is directly related to the quality, volume, and regularity of the water flow. Traditionally qanats are built by a group of skilled laborers, muqannīs, with hand labor. The profession historically paid well and was typically handed down from father to son. According to most sources, the qanat technology was developed in ancient Iran by the Persian people sometime in the early 1st millennium BC, and spread from there slowly westward and eastward. However, some other sources suggest a Southeast Arabian origin.In arid and semi-arid regions, owing to high evaporation, transportation routes were in the form of ganats, which lead groundwater to consumption areas along underground tunnels. In the long run, the qanat system is not only economical but also sustainable for irrigation and agricultural purposes... The ground water flow was known to depend on grain size of sediments, and, therefore, the tunnels in qanats are filled in with coarser material than the surrounding hose geological formations. The qanats are constructed mainly along the valleys where Quartenary sediments are deposited.The air is the most marvellous I ever was in, in any city. Mountain air, so sweet, dry and 'preserving', delicious and life-giving.' She told of running streams, and fresh water bubbling up in the gardens. (This omnipresence of water, which doubtless spread from Persia to Baghdad and from there to Spain during its Muslim days, has given Spanish many a water-word: aljibe, for example, is Persian jub, brook; cano or pipe, is Arabic qanat—reed, canal. Thus J. T. Shipley, Dictionary of Word Origins). A qanat or kariz is a gently sloping underground channel to transport water from an aquifer or water well to surface for irrigation and drinking, acting as an underground aqueduct. This is an old system of water supply from a deep well with a series of vertical access shafts. The qanats still create a reliable supply of water for human settlements and irrigation in hot, arid, and semi-arid climates, but the value of this system is directly related to the quality, volume, and regularity of the water flow. Traditionally qanats are built by a group of skilled laborers, muqannīs, with hand labor. The profession historically paid well and was typically handed down from father to son. According to most sources, the qanat technology was developed in ancient Iran by the Persian people sometime in the early 1st millennium BC, and spread from there slowly westward and eastward. However, some other sources suggest a Southeast Arabian origin. Common variants of qanat in English include kanat, khanat, kunut, kona, konait, ghanat, ghundat. Qanāh (قناة) is an Arabic word that means 'channel'. In Persian, the words for 'qanat' are kārīz (or kārēz; كاريز), and is derived from earlier word kāhrēz (كاهریز). The word qanāt (قنات) is also used in Persian. Other names for qanat include kahan (Persian: کهن‎), Kahn (Balochi), kahriz/kəhriz (Azerbaijan); khettara (Morocco); Galerías, minas or viajes de agua (Spain); falaj (Arabic: فلج‎) (United Arab Emirates and Oman), foggara/fughara (North Africa). Alternative terms for qanats in Asia and North Africa are kakuriz, chin-avulz, and mayun. Traditionally it is recognized that the qanat technology was invented in ancient Iran sometime in the early 1st millennium BC, and spread from there slowly westward and eastward. Accordingly, some sources state qanats were invented in Iran before 1000 BC and as far back as 3000 BC. Consequently, the qanats of Gonabad have been estimated to be nearly 2700 years old. In 2002, archaeologist Walid Yasin Al Tikriti provided a counterpoint that the qanat did not originate in Persia. As evidence, he noted seven Iron Age aflaj recently discovered in the Al Ain area of the UAE which were dated back to the first millennium BCE based on sherds, pottery, fireplaces, and architecture. Tikriti pointed to excavations in Sharjah, by the French archaeological team working there, as well as a German team working in Oman of possible Iron Age aflaj. He concludes that the technology originated in South East Arabia and was taken to Persia, likely by the Sasanian conquest of the Oman peninsular. In 2013, Boualem Remini and Bachir Achour, stated that the origin of the qanat technology is uncertain, yet confirmed the technology was in use in northwest Iran c.1000 BCE. In 2016, Rémy Boucharlat in his paper Qanāt and Falaj: Polycentric and Multi-Period Innovations Iran and the United Arab Emirates as Case Studies, asserted that the attribution of the technology to Iranians in the early first millennium BCE is a position that cannot longer be maintained. Whereas Boucharlat contends archeological evidence indicates a polycentric innovation as opposed to a radial diffusion. The original ancient engineered design of the Qanat and its multiple aligned bore-holes are thought to have controlled desert endorheic basin flooding without destroying the salt mirror playa or causing erosion of the flat evaporation fields. The Qanat water was primarily needed to extract salt, rather than for simple domestic irrigation. Additionally considerable quantities of subsoil brines existing in such basin water tables would ensure brine supplies, as is demonstrated by the new potash plants in the Tarim basin using the ancient Qanat technology. The surface crust of an inland Sabkha endorheic basin typically is made up of layers of salts that have re-crystallized and settled or precipitated during the evaporation process of controlled Qanat system flood waters. Leached salts dissolve quickly in a desert endorheic basin, and over a short intensely hot period, the process of re-crystallizing the salts can produce purer and more concentrated, layered playa cakes. The dissolved salts leached out of the underlying layers in such vast desert basin flats, are intermittently precipitated back onto the basin surface, predominantly sodium chloride crystals, one after the other. It is thought that the many Qanat systems in the Taklamakan desert basin (Tarim basin) were primarily built to produce and trade salt along the Silk Road. The position of the Silk Road skirting these endorheic basins may well have resulted due to efficient and pure salt leaching technique still producing salt cake crust in similar deserts. Qanats are constructed as a series of well-like vertical shafts, connected by gently sloping tunnels. Qanats efficiently deliver large amounts of subterranean water to the surface without need for pumping. The water drains by gravity, typically from an upland aquifer, with the destination lower than the source. Qanats allow water to be transported over long distances in hot dry climates without much water loss to evaporation.