The Sustainable Irrigation System of Persia, The Qanat

By Somayeh Zahabnazouri, IUCN CEM Young Professional.

A qanat is an underground water system that transports groundwater from a well called the Mother well at high elevation to a surface output spring at an elevation much lower than the Mother well through an underground tunnel or aqueduct. Because the elevation of the Mother well remains constant, it does not lower the groundwater and is, therefore, a sustainable way to tap groundwater without inflicting any deterioration of the aquifer.

Qanat (Photo: Ahmad Jabbari)

It is a very ancient, low-tech irrigation system used in central Iran and other areas of the Middle East and in many arid and semi-arid regions around the Mediterranean and even South America. The qanat irrigation technology and related knowledge system have been recorded in historical sources as early as 800 BC by Persian people, but recent optical dates on the Miam Qanat (KĀRIZ) system in NE Iran indicate that it is at least 3,600 to 4,300 years old, making it the oldest known qanat system in Iran. The well-developed technology of this system suggests that there may be much older qanat systems in Iran.

The main reason for the expansion of Qanat technology is that this irrigation method has developed according to special ecological conditions of the Iranian plateau so that its design is especially suited for use in arid and semi-arid areas. After its success in Iran, it was expanded to other regions of the eastern Mediterranean and eventually around the world, where environmental conditions were similar to those found in the Iranian plateau. The export of this technology may even have occurred prior to the expansion of the Persian Empire. There is some evidence for Qanat systems in the Western Desert of Egypt during the Middle Kingdom.

The significance of Qanats

The most important role of the Qanat is to provide a sustainable water supply for subsistence farmers in arid and semi-arid regions. It has been the primary source and, in some areas, the only source of water for both drinking and growing food crops. More recently, it has become important for watering commercial agricultural products such as palm, pistachio, saffron, and wheat in the arid and semi-arid regions of the Iranian Plateau. Because Qanats have been used in Iran for thousands of years, it has become a symbol of its civilization, tradition, and culture in the desert regions.

Perhaps the greatest benefit of this water extraction method is that it maintains the balance between water input and output in the aquifer. In so doing, it helps preserve groundwater. The people in Iran understand the importance of the Qanat system in sustaining natural ecosystems and maintaining the lifeways and economies of the people of the arid regions of the Middle East. So we have initiated a campaign to return life to the deserts’ Qanat systems and educate those who still do not recognize the importance of the Qanat system in Iran.

Certain practices currently being conducted in the dry regions of Iran, especially the drilling of deep wells and the pumping the groundwater to dangerously low levels, are not conducive to maintaining the environment. Deep well water pumping steals water from the Qanat systems and eventually destroys the entire regional water table. At current rates, deep well water pumping will force the abandonment of most of central and southern Iran within the next 20 to 30 years. An additional problem that deep well pumping is causing is the subsidence of valley floors due to the lowering of the groundwater level. It is already predicted that the many plains in central Iran will experience significant subsidence due to dewatering by deep wells and heavy pumping of water.

Qanats provide many environmental benefits; This irrigation system has developed in response to the special ecological conditions in the hot and semi-arid areas of the Iranian Plateau. The discharge of Qanat water and fluctuation in its discharge between wet and dry years plays an important role in desert biodiversity.

Current threats faced by Qantas

Despite all of the benefits of Qanats in arid regions, they are vulnerable to flash floods, earthquakes, and other natural hazards and anthropogenic interference such as drilling deep wells. During the last few decades, many qanats in the area of Iran ranging from Kerman in the south to Saveh in the north and the Tehran Valley have dried because of: 1) drought and resulting in reduced recharge of the aquifer, and 2) drilling deep wells and extracting the huge amount of water. This has resulted in significant land subsidence that poses an additional problem to the drying of Qanat systems.

Our Plain to Conserve Qanats

The campaign has been working on raising awareness about Qanats by conducting fieldwork, presenting webinars, and sessions on various subjects related to Qanats, including:

  • Introduction to Qantas
  • Qanat types and their role in the past and the 21st century
  • Qanat problems (flood, earthquake, deep wells, replacing Qantas with wells, electrical power, magnetic power, climate change, etc.)
  • Management, maintenance, and rehabilitation problems related to Qantas
  • Qanat tourism, their cultural importance and Qanats as a natural and national heritage
  • Qanat management and coordination systems
  • Qanats and technology
  • Qanats and media and virtual world
  • Qanats and agriculture and subsistence livelihood
  • Qanats, education, and research
  • Qanats and vulnerability (natural and man-made)
  • Qanats and their historical, social, political, cultural,…position
  • The environmental and local benefits of Qanats

Ms Somayeh Zahabnazouri is currently a PhD Graduate in Physical Geography at the University of Tehran.

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