Qanat

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The Qanat is an ancient water supply system that originated in the arid regions of ancient Persia, now Iran, around 3,000 years ago, though some estimates suggest they could be older. This innovative system was developed to transport water from underground aquifers in the mountains to the surface in valleys and plains for irrigation, drinking, and other uses, especially in regions where surface water was scarce or unavailable.

The principle behind a qanat is relatively simple but highly effective. It involves digging a gently sloping tunnel from a water source in the mountains towards the desired destination. The slope allows water to flow by gravity along the length of the tunnel to the surface in areas where it is needed. Along the tunnel, vertical shafts are excavated at regular intervals to provide ventilation and for the removal of debris during construction. These shafts appear as a series of well-like holes on the surface, leading down to the underground channel.

The qanat system was a sustainable way to access groundwater without depleting the source, and it allowed communities in some of the most inhospitable environments to flourish. The technology spread from Persia to other parts of the world, including the Arabian Peninsula, North Africa, Spain, and China, often through the expansion of the Persian Empire and later through Arab conquests.

The effectiveness of qanats in providing a reliable water supply led to the development of sophisticated agricultural and urban societies in desert regions. Many qanats are still in use today in Iran and other countries, testifying to the durability and sustainability of this ancient engineering marvel.

****How did they prevent the tunnel collapsing in long term?

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To prevent the tunnels of qanats from collapsing over the long term, ancient engineers and workers employed several ingenious methods and techniques, highlighting their advanced understanding of geology, hydrology, and civil engineering. Here are some of the key strategies used to ensure the structural integrity of qanats:

1. Lining the Tunnels: In areas where the earth was loose or unstable, the tunnels were lined with stone, brick, or other durable materials to prevent collapse. This reinforcement was especially common in sections of the tunnel where the water flow was strong, which could erode the tunnel walls over time.
2. Regular Maintenance: Qanats required regular maintenance to remove sediment buildup and repair any damage. This maintenance was typically the responsibility of the community that benefited from the qanat, and skilled workers, known as “muqannis,” were trained specifically for this purpose. They would descend into the vertical shafts to clean and repair the tunnels, ensuring their long-term viability.
3. Careful Planning and Construction: The construction of a qanat was a highly skilled task that began with careful planning to determine the most stable path for the tunnel. This often involved extensive knowledge of the local geology to avoid areas prone to collapse or erosion. The gradient of the tunnel was also carefully calculated to ensure a consistent flow of water without undermining the structure’s stability.
4. Use of Supporting Arches: In some cases, especially where the tunnel passed through less stable ground, supporting arches were constructed within the tunnel to provide additional structural support and prevent collapse.
5. Strategic Placement of Shafts: The vertical shafts, which were used both for construction and maintenance, also played a role in stabilizing the tunnel. They were strategically placed at regular intervals to ensure that any part of the tunnel could be easily accessed for repairs. Additionally, the act of removing material to create these shafts helped to relieve pressure on the tunnel walls.
6. Adopting Local Geological Features: Where possible, builders of qanats would take advantage of the natural geological features, such as rock layers or compacted soil, that could provide a more stable environment for the tunnels.

These techniques, combined with the community’s ongoing commitment to maintenance, have allowed many qanats to remain in operation for centuries, with some still functioning after more than a thousand years. The success of these ancient engineering projects lies not only in their initial construction but in the sustainable practices developed to maintain them.

****List the areas where quants still in use.

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Qanats, a remarkable ancient water management system, are still in use in various parts of the world, especially in arid and semi-arid regions where traditional methods of water supply are essential for agriculture and daily life. Here’s a list of areas where qanats are still utilized:

1. Iran: Iran, the birthplace of qanats, has thousands of these systems still in operation today, supplying water to cities, villages, and farms across the country. The city of Yazd, in particular, is famous for its qanats.
2. Oman: In Oman, qanats are known as aflaj (singular: falaj), and they are crucial for irrigation in rural areas. The aflaj system is so culturally significant that some of them are listed as UNESCO World Heritage Sites.
3. Afghanistan: In Afghanistan, qanats are called karez (or kariz), and they are vital for irrigation and drinking water, especially in the regions around Herat and Kandahar.
4. China: In the Xinjiang Uygur Autonomous Region of China, qanats (locally known as karez) provide water to the oasis towns and agricultural lands in this desert area.
5. Syria: Though significantly impacted by ongoing conflicts and water management challenges, qanats are still an important water source in some rural areas of Syria.
6. Iraq: In Iraq, qanats (known as karez) have historically been used to irrigate the fields and supply water to the villages, particularly in the Kurdish regions in the north.
7. Saudi Arabia: Saudi Arabia also has historical qanats, although many have been replaced or supplemented by modern water supply methods due to the country’s wealth from oil.
8. United Arab Emirates: The UAE, similar to Oman, has traditional aflaj systems that are still in use in parts of the country, supporting agriculture and providing water to small communities.
9. Morocco: In Morocco, qanat-like systems are found in the southern oases, where they are known as khettara. They play a crucial role in the irrigation of palm groves and agriculture.
10. Yemen: In Yemen, despite the challenges posed by the country’s complex water crisis and ongoing conflict, traditional water systems, including qanats, are used in some areas.

These traditional systems are a testament to the ingenuity of ancient engineering and are often integrated with modern water management practices to sustain communities in arid regions around the world. Their continued use highlights the importance of sustainable and locally adapted water management strategies.

****In some areas, quant is used to cool air indoors, and make “ ice storage “possible in the summer.

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Yes, in some regions, particularly in ancient Persia (now Iran) and surrounding areas, qanats were ingeniously used not only for irrigation and drinking water but also for cooling air indoors and creating ice storage, even during the hot summer months. This innovative use of qanats showcases the ancient world’s sophisticated understanding of natural air conditioning and refrigeration techniques. Here’s how these systems worked:

Cooling Air Indoors

1. Wind Towers (Badgirs): Wind towers, or badgirs, were used in conjunction with qanats to cool buildings. The wind tower would catch cooler breezes at a higher elevation and direct them down into the building. When this air traveled over the water flowing in the qanat or open water pools (howz), it would cool down before entering the living spaces, thus reducing indoor temperatures.
2. Qanat Cooling: In some cases, the air was directly drawn from the qanat tunnels themselves, which remained at a much lower temperature than the surface air. This cool air would be channeled into basements or living areas to reduce the temperature. The flow of air through the qanat also helped to ventilate the tunnel system and prevent the air from becoming stagnant.

Ice Storage (“Yakhchāl”)

1. Yakhchāl (Ice Storage): The yakhchāl, which literally means “ice pit” in Persian, was an ancient type of evaporative cooler. This dome-shaped structure was designed to store ice and food items, keeping them cool even in the hot summer months. The walls of a yakhchāl were made from a special type of mortar (sarooj) that was highly insulating, allowing the interior to remain cool.
2. Creating Ice: During the colder months, water from a qanat would be channeled into shallow pools where it would freeze overnight. The ice would then be cut and stored in the yakhchāl. The thick insulation and the continuous cooling effect of evaporation kept the ice from melting.
3. Evaporative Cooling: The design of the yakhchāl, often with a subterranean storage area, facilitated the cooling of air through evaporation. As hot air entered the structure, it would be cooled by the evaporation of water (from both the ice and the moisture inside the yakhchāl), thus reducing the temperature inside the storage area.

These ancient cooling techniques were remarkably effective, enabling people living in some of the hottest parts of the world to enjoy cooler indoor temperatures and have access to ice year-round, long before the advent of modern refrigeration and air conditioning technologies.