Qanat
Ancient underground aqueducts delivering water by gravity in arid regions.
A qanāt (Persian: قَنَات) or kārīz (کَارِیز) is an underground water supply system developed in ancient Iran approximately 3,000 years ago. It transports usable water from an aquifer or well to the surface via a gently sloping tunnel, minimizing evaporation and relying on gravity, thus eliminating the need for pumping. The system is known by various regional names across Asia and North Africa, including kārēz in Afghanistan and Pakistan, foggāra in Algeria, khettāra in the Atlas Mountains, daoudi-type falaj in Oman and the United Arab Emirates, and ʿuyūn in Saudi Arabia. Qanat-style systems were also introduced to parts of Europe under the Roman Empire and later in Muslim-ruled Spain, and may have influenced or paralleled pre-Columbian systems in the Americas.
- origin
- Ancient Iran (Persia), early 1st millennium BCE
- other_regional_names
- kārīz, kārēz, foggāra, khettāra, falaj, ʿuyūn
- primary_function
- Transport groundwater to surface for irrigation and consumption
- key_advantage
- Resistant to evaporation, natural disasters, and wartime destruction
- largest_extant_systems
- Afghanistan, Xinjiang (China), Oman, Pakistan, Iran
- etymology
- From Akkadian qanû(m) 'reed'; Arabic qanāh 'spear' or 'channel'; Persian kārīz
Lore & Background
According to most sources, qanat technology was developed by the ancient Iranians in the early 1st millennium BCE and slowly spread westward and eastward. Other sources suggest a Southeast Arabian origin. One theory holds that the qanat was developed to irrigate cotton fields, first in what is now Iran, where it doubled the amount of available water for irrigation and urban use, leading to larger agricultural surpluses, urbanization, and social stratification. The technology subsequently spread from Persia westward and eastward. In the arid coastal desert of Peru, a similar system called puquios was developed; most archaeologists believe they are indigenous and date to about 500 CE, though a few argue for a Spanish origin in the 16th century.
Reader's Guide
The qanat system has proven crucial to water supply in hot, dry climates, enabling water transport over long distances with minimal evaporation. It is resistant to natural disasters such as floods and earthquakes, and to man-made disasters like wartime destruction and water supply terrorism. The system is almost insensitive to varying levels of precipitation, delivering a flow with only gradual variations from wet to dry years. Powered solely by gravity, qanats have low operation and maintenance costs and help control soil salinity and prevent desertification. Their value to a population is directly related to the quality, volume, and regularity of groundwater in the region. Many continuously inhabited settlements in West Asia and North Africa are notably established in areas favorable for creating and sustaining a qanat system. The typical design includes a gently sloping tunnel accessed by a series of well-like vertical shafts visible at ground level, tapping into groundwater and delivering it to the surface at a lower level. Water is typically used only once it emerges from the daylight point. The qanat should not be confused with the spring-flow tunnel typical to the mountainous area around Jerusalem, as the origin and construction methods differ.
Did You Know?
- The word qanat originates from the Akkadian word qanû(m), meaning 'reed'.
- Qanats are resistant to both natural disasters like floods and earthquakes and man-made disasters such as wartime destruction.
- A similar system called puquios was developed in the Nazca region of Peru, with most archaeologists dating it to about 500 CE.
- The largest extant and functional qanats are located in Afghanistan, Xinjiang in China, Oman, Pakistan, and Iran.
More in World Heritage Sites in Iran 1-24
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