The Flushwater Term of the Day: Qanat
Throughout history, mankind (ladies included, of course!) has developed ingenious systems and techniques, even in the absence of technology, to ensure readily available supplies of water. One such system, known as a qanat, delivers water from reliable groundwater sources downhill to thirsty towns and villages below. One attractive feature is that qanats don’t have to be financed, there are no expensive parts to break, and they require little to no local infrastructure. Qanat construction, though, does have its downside -about six feet deep, if you get my drift. Nevertheless, many people still rely on this traditional method of water delivery.
A qanat consists of a long tunnel or conduit leading from a well dug at a reliable source of groundwater (the mother well). Often, the mother well is dug at the base of a hill or in the foothills of a mountain range. The tunnel leading from the mother well slopes gradually downward to communities in the valley below. Access shafts are dug intermittently along the horizontal conduit to allow for construction and maintenance of the qanat.
The advantages of qanats are numerous, especially for poor countries in hot, dry areas, which is why qanats are common in parts of China and Middle Eastern countries like Iran, Afghanistan, and Pakistan. The use of gravity to deliver the water in a qanat eliminates the need for expensive pumping. The water stays clean and potable because it travels underground until it is accessed in towns, villages, and farms along the way. This also greatly reduces loss of water due to evaporation. If dug correctly, a qanat will provide a reliable, nearly static water supply even in very dry years. Finally, the manner in which qanats are constructed causes them to resist natural disasters (earthquakes, tornadoes, flooding) as well as deliberate sabotage or destruction.
New qanats are constructed very rarely, if ever. Back in the day, a new qanat where none existed previously was a very good thing, if you were a thirsty villager or farmer. If you were a slave or a member of the lower classes, a new qanat wasn’t such a good thing, because you were the one that had to dig it – by hand. Digging a qanat was very dangerous, and the death-rate among diggers was very high. Workers often wore their funeral clothes so that their fellow diggers wouldn’t have to stop working to dig them them out in the event of a cave-in, which was quite common.
Qanat is also known as a foggara or foggaras, a kariz or karez, or a falaj. Qanats are often diverted into small storage reservoirs intended to hold the daily supply. Such a reservoir is sometimes known as an ab anbar.