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Posts Tagged ‘Anthony Smith’

My traditional pre-holiday reading was focussed on the extreme summer heat and not just how I was going to cope but also how the Iranians manage year after year during the seeringly hot summer months when temperatures can soar over 40 degrees centigrade in many areas. Inevitably, much of my research concerned water consumption and distribution in regions where much of the land is arid or semi-arid and how crops are grown in rural areas without regular rainfall. Was I going to be eating the luscious melons that Esfahan is so famous for or would they all be withered up left to dry out in the fields? I also wondered whether we would be subject to water rationing at home and, heaven forbid, would there be a ban on hosepipes?

 

It was when reading about these problems that I came across an ingenious solution to water distribution, the Qanat system. This underground aqueduct system is known to have been developed by the Persians sometime early in the 1st millennium BC, around the same time that we Britons were fighting off the Roman invasion led by Julius Caesar. Qanats were subsequently adopted by Arab and African countries further West and the remains of Qanats can still be found in China, Pakistan, Syria, UAE, Algeria, Greece and Spain.

So what is a Qanat? Simply, a Qanat is a series of shafts connecting ground level to sloping tunnels below ground. The theory is that the Qanats tap into the water underground so that it brings large quantities of water to the surface up the shafts without the need for a pumping mechanism. The water drains by gravity as it flows downwards from the aquifer source towards its destination. Because the canals are underground, there is little or no evaporation or wasteage and contamination is kept to a minimum. Qanats are usually contructed to cover a large area/distance which means that many fields and homes can be kept watered. Qanats were both expensive and time-consuming to build but it was considered a major investment by the communities who needed reliable water supplies for many years to come. That initial investment must have repaid them many-fold and the Qanats are a wonderful legacy.

Qanat cross section

Qanat cross section-diagram courtesy of the Middle East Institute

 

Building the Qanats is a skilled occupation and knowledge was generally passed through families from father to son. The gradient of the Qanat has to be just right if it is to be successful. Too shallow and the water will not flow; too steep and the heavy flow of water is likely to collapse the Qanat by washing it away. Bearing in mind that these shafts and tunnels were excavated by hand, without the sophisticated machinery we have today, they are amazing to see. If the Qanat diggers were lucky, they would initially hit the water aquifer at 50ft. Unfortunately for the labourers many of the shafts are 200-300 feet deep. Most Qanats are between 8-10 miles long with the longest Qanat in Iran being 18 miles long.

“In Persia, blind white fish live in the qanats.” This statement led four Oxford undergraduates to Iran in the early 1950’s to look for a new species of fish which apparently lived in the qanat water system and a book detailing their travels and exploits can still be found in secondhand bookshops. Keep an eye out for “Blind white fish in Persia” by Anthony Smith. It is well worth a read.

The Old Mosque in Na’in has a Qanat in the underground chambers although it is no longer in use. When it was used, it carried water for 1.2km to the left of the town and 1.5 km to the right thus serving much of the community around. Qanats are often used in conjunction with wind towers (Badgirs) and Yakhchals (ice houses) which are separate above-ground structures combining to cool air and water-an early version of air-conditioning and refrigeration and not a watt of electricity in sight.

“Necessity is the mother of invention” [Plato]

Perhaps these ideas can be adapted for future use as more sustainable options.

 

 

 

 

 

 

 

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