by Carl Pierer
Yazd, one of the big three Tourist destinations in central Iran, has a rather challenging climate. With summer temperatures often exceeding 40C and hardly any precipitation at all (49 mm per year), water is a major concern. The city is rightfully famous for its wind towers (بادگیر) and qanats (قنات). While the former were and sometimes still are used for cooling houses, water reservoirs or storage rooms, the latter used to provide the city with water. Walking through the city, located in this rather inhospitable environment, one is constantly reminded that question of water dominates many aspects of life: from the garden and parks to agriculture and industry, from housing location to food storage and cooling. For many of these, the ingenious use of qanats provided an answer.
A qanat is an underground aqueduct, which uses gravity to direct water from a well or aquifer to the surface. In distinction from wells, this feat of engineering allows to transport water over great distances to places where it might be difficult to access. Moreover, because the channels run underground, there is not too much loss through evaporation or danger of pollution. The first qanats are thought to have been constructed in today’s Iran, sometime between the 10th and 8th centuries BCE. [1] The concept was so successful that it spread far: initially spreading beyond the core area of the Iranian plateau with the expansion of the Persian Empire in the Achaemenid period (5th – 3rd century BCE), the technology spread eastwards to Afghanistan, Pakistan, and to the Indus river; westwards to the Levant and the Mediterranean shore, and south to Egypt and Saudi Arabia. In a second wave, the technology spread with Islam to Cyprus, and across North Africa to Spain and the Canary Islands. [2] There are even qanats found in Japan [3] and in Latin America, in Mexico, Peru, and Chile, which appear to pre-date the Spanish invasion, thus becoming “(…) an additional item in the continuing pre-Columbian trans-Pacific diffusion controversy”. [2]
Writing in 1968, Paul English [2] states that in Iran alone 15 million acres (roughly 6 million hectares, or 60.000 km2) of cultivated land are watered by 37.500 qanats. This, at the time, corresponded to between one-third and a half of the total cultivated land. Historically, they provided up to ¾ of the water used in Iran. [1] Being such an important feature of Iranian cities, it is worth looking at some of their technical details. Read more »