Qanat System

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Context

• Some of Africa’s dry areas face serious water shortages due to minimal rainfall.
• An ancient system of drawing water from aquifers, the “qanat system”, could help.

Qanat System:

• The Qanat system, an ancient and ingenious method of water management, has played a pivotal role in sustaining agriculture and settlement in arid and semi-arid regions for centuries. Originating in Persia (modern-day Iran), the Qanat system has been adopted across various parts of the world with arid climates.

Key Components:

Qanat Shaft (Mother Well):

• The system begins with the construction of a vertical shaft, known as the mother well, dug into an elevated terrain where water is present underground.

Underground Channels:

• From the mother well, a gently sloping underground channel (qanat) is excavated to transport water to the desired location.

Access Shafts (Kareez):

• Periodic vertical shafts, known as kareez, are dug along the qanat to facilitate maintenance, ventilation, and access to water.

Terminal Well:

• The qanat culminates in a terminal well, which acts as a distribution point for the extracted water. This well feeds into a surface canal or directly irrigates agricultural fields.

Advantages of Qanat System:

Conservation of Water:

• The qanat system significantly reduces water loss through evaporation and seepage, ensuring efficient water conservation.

Temperature Regulation:

• The underground channels shield water from the scorching heat, preventing excessive evaporation and maintaining a more stable temperature.

Sustainable Agriculture:

• Qanats have enabled the cultivation of crops in regions where surface water is scarce, fostering sustainable agriculture and supporting human settlement.

Community-Based Management:

• The construction and maintenance of qanats traditionally involve community efforts, promoting a communal approach to water resource management.

Environmental Resilience:

• Qanats contribute to environmental resilience by harnessing subterranean water sources, reducing the reliance on surface water vulnerable to climate fluctuations.

Historical Significance:

• The Qanat system has a rich historical legacy, dating back to the first millennium BCE.
• Its successful implementation facilitated the growth of ancient civilizations in regions such as Persia, Mesopotamia, and the Middle East.

Challenges:

• Despite its effectiveness, the Qanat system faces challenges, including declining water tables due to over-extraction, inadequate maintenance, and competition with modern water supply systems.

Global Spread:

• The Qanat system has transcended its Persian origins and found adaptations in various countries, including North Africa, Central Asia, China, and Spain, attesting to its universal applicability in arid climates.

Why is it not being more widely used?

• There are several reasons why the tunnel system is not more widely used in Africa.
• Qanats need to be built somewhere with the right geological formations. These generally seem to be fractured sandstones. The level of groundwater is also important for the flow of water in the qanat. The volume of water in the aquifer stems from the rainfall in the mountainous regions.
• Qanats can only be built where there’s a slope, like a mountain or a valley. And the slope must have a specific angle. If it’s too steep, erosion of the qanat will occur and it will collapse. If it’s not steeped enough the water will not flow fast enough and could become chemically altered due to interaction with minerals in the ground.
• The digging of the tunnel and development of the system over large areas of land is labor-intensive and can take many years. The qanats cover many kilometres and need to be maintained every year, by cleaning out the silt build-up.
• Knowledge of building qanats and maintaining them is being lost. People have migrated from rural areas to cities and adopted boreholes in certain areas instead.
• Some qanats are drying up due to over-exploitation of the water resource.

Why should the system be used more widely?

• In most instances people in arid areas drill wells to access groundwater. These boreholes have a lifespan and eventually new wells have to be drilled. Pumps and materials don’t last forever and wells can get clogged by microbial organisms and fine material in the subsurface.
• First, the qanat is sustainable as it works with gravity, and no electricity is needed. It can even be used to create clean energy. For instance, in Iran, cold air that comes out of qanat tunnels is used to coolthe interior of large buildings.
• Second, water lost to evaporation is minimal in comparison to surface water
• Third, it can have a wide-scale impact. Qanats are multiple kilometres long and once this water hits a floodplain, it can irrigate multiplehectares of land.
• Fourth, it fosters social cohesion. Many people, with different skills, are involved in maintaining the system.
• Fifth, the lifespan of the system extends beyondthat of a deep water well, which is only about 20 years. Tunnels do not clog as easily as wells.
• Finally, the quality of water coming from the mountains is much better than water on the plains. It’ll have lower salinity and be better for crops and people.

Conclusion:

• The Qanat system stands as a testament to human ingenuity in harnessing and managing water resources in arid regions.
• Its sustainable principles continue to inspire modern water management practices aimed at addressing the challenges of water scarcity.

PRACTICE QUESTION Question: Which of the following statements accurately reflects one of the key advantages of the Qanat system, as highlighted in the provided context? A.      Conservation of water through reduced evaporation and seepage B.      Utilization of modern water supply systems for sustainability C.      Support for human settlement through extensive irrigation of deserts D.      Minimization of groundwater extraction through electric pumps Answer: A. Conservation of water through reduced evaporation and seepage Explanation: The context mentions that one of the key advantages of the Qanat system is the significant reduction of water loss through evaporation and seepage. This reflects the system's efficiency in conserving water, making option A the accurate statement. The Qanat system doesn't rely on electric pumps, as mentioned in option B, and while it supports sustainable agriculture and human settlement, the specific advantage related to water conservation is highlighted in option A. Option C incorrectly suggests extensive irrigation of deserts, which is not explicitly mentioned in the context. Option D is also incorrect as it misrepresents the Qanat system's reliance on gravity, not electric pumps.  PRACTICE QUESTION Question: What is the Qanat system, and how does it contribute to water management? Choose the correct statement(s) from the options below: A) The Qanat system is an ancient agricultural technique used for crop irrigation, originating in ancient China. B) Qanats are underground tunnels that tap into groundwater sources and transport water to the surface for various purposes. C) The Qanat system is primarily associated with the Inca civilization and played a crucial role in their advanced agricultural practices. D) The Qanat system relies on windmills to pump water from underground aquifers to the surface, facilitating irrigation in arid regions. E) Qanats have been historically employed in regions such as Iran, North Africa, and the Middle East, showcasing their significance in water management. Choose the correct combination: B and E A and C B, D, and E C and D A and B The correct combination is: B and E Explanation: A) Incorrect - The Qanat system does not originate from ancient China. It is associated with regions such as Iran, North Africa, and the Middle East. B) Correct - Qanats are underground tunnels that tap into groundwater sources and transport water to the surface for various purposes, including irrigation. C) Incorrect - The Qanat system is not primarily associated with the Inca civilization; it has historical roots in the Middle East and other arid regions. D) Incorrect - The Qanat system does not rely on windmills; it uses a gravity-driven system to bring groundwater to the surface. E) Correct - Qanats have been historically employed in regions such as Iran, North Africa, and the Middle East, showcasing their significance in water management.