UNESCO Water e-Newsletter No. 186: QANATS
27 April 2007
2005-2015 is the International Decade For Action 'Water for Life'
|Air pollution from industry|
© UNESCO – Jacques Perez
30 April – 3 May: IPCC Working Group III plenary session, Bangkok, Thailand
‘Mitigation climate change’ is the Intergovernmental Panel on Climate Change (IPCC) Working Group III contribution to the 4th IPCC Assessment Report, ‘Climate Change 2007’. It focuses on mitigation of climate change through limiting or preventing greenhouse gas emissions and enhancing activities that remove them from the atmosphere.
Climate change is having a significant impact on weather patterns, precipitation and the hydrological cycle, affecting surface water availability, as well as soil moisture and groundwater recharge. A recent study estimates that climate change actually accounts for about 20% of the global increase in water scarcity, the remaining 80% accounted for by population growth and economic development.
The report on mitigation and its summary for policy makers are being revised and approved by Member States during a plenary session of Working Group III taking place Bangkok, Thailand from 30 April to 3 May 2007. The summary for policy makers will be launched officially in on 4 May 2007.
International Congress on Development, Environment and Natural Resources: Multi-level and Multi-scale Sustainability
11-13 July 2007, Cochabamba, Bolivia -Organizers: University Mayor of San Simon, Bolivia; Flemish Interuniversity Council (VLIR) – University Development Cooperation (UOS), Belgium
30th Congress of the International Association of Theoretical and Applied Limnology
12-18 of August 2007, Montréal, Canada -Organizers: International Association of Theoretical and Applied Limnology (SIL); Interuniversity Research Group in Limnology and Aquatic Environment (GRIL), Canada; Society of Canadian Limnologists (SCL)
6th Inter-American Dialogue on Water Management ‘From Dialogue to Action: Strengthening partnerships and building the basis for achieving the Millennium Development Goals’
12-17 August 2007, Guatemala City, Guatemala -Organizers: Inter-American Water Resources Network (IWRN); Government of Guatemala
10th International Riversymposium and Environmental Flows Conference
3-6 September 2007, Brisbane, Australia -Organizers: Brisbane City Council, Australia; Queensland Government, Australia
International Symposium on ‘New Directions in Urban Water Management’
12-14 September 2007, UNESCO Headquarters, Paris, France -Organizer: UNESCO’s International Hydrological Programme
DID YOU KNOW...? FACTS AND FIGURES ABOUT QANATS
- Qanat (karez or foggara) irrigation systems are ancient (circa 800 BC) and consist of underground tunnels constructed into a cliff, scarp or base of a mountainous area, following an aquifer, or from rivers, to bring water out to the surface. The tunnels are straight and horizontal with a slope to allow the water to drain out into an oasis or irrigation system.
- The volume of water produced by qanats depends on the type and extent of the aquifer, and its recharge rate. When tunnelling horizontally, air shafts 15-55 meters deep are constructed every 15-47 meters to remove the mined soil, clean the tunnels of silt, and aerate the tunnels.
- There are significant advantages to a qanats water delivery system including: (1) putting the majority of the channel underground reduces water loss from seepage and evaporation; (2) since the system is fed entirely by gravity, the need for pumps is eliminated; and (3) it exploits groundwater as a renewable resource.
- During the period 550-331 BC, when Persian rule extended from the Indus to the Nile, qanats technology spread throughout the empire. To the west, qanats were constructed from Mesopotamia to the shores of the Mediterranean, as well as southward into parts of Egypt. To the east of Persia, qanats were constructed in Afghanistan, the Silk Route oases settlements of central Asia, and Chinese Turkistan.
- During Roman-Byzantine era (64 BC to 660 AD), many qanats were constructed in Syria and Jordan. From here, the technology appears to have diffused north and west into Europe. There is evidence of Roman qanats as far away as the Luxembourg area.
- The expansion of Islam initiated another major diffusion of qanat technology. The early Arab invasions spread qanats westward across North Africa and into Cyprus, Sicily, Spain, and the Canary Islands. Evidence of New World qanats can be found in western Mexico, in Peru and Chile.
- Qanats irrigated agriculture is threatened by silt sedimentation in canals, moving sand dunes, urban migration of youth, and decline of experts for managing such systems.
- In Iran alone there are an estimated 50,000 qanats. Assembled end to end, they would reach two-thirds of the way to the moon.
Information from the International Center on Qanats and Historic Hydraulic Structures website, from the Globally Important Agricultural Heritage Systems website section ‘Qanat Irrigation Systems and Homegardens (Iran)’ and from the qanats section of the WaterHistory.org website.
PUBLICATIONS RELATED TO QANATS
Qanats a Unique Groundwater Management Tool in Arid Regions: The Case of Bam Region in Iran [PDF format – 98 KB]
By Abdin Salih. Paper presented at the International Symposium on Groundwater Sustainability (ISGWAS), January 2006
For rational management of groundwater a holistic approach, linked to the sustainable management of the ecosystem, must be developed. It is demonstrated that ancient methods of groundwater management, such as the qanats system, could provide a good example of human ingenuity to cope with water scarcity in a sustainable manner. The catastrophic earthquake of Bam has drawn the attention of researchers and professionals to a great human heritage related to the sustainable management of groundwater in arid zones and the development of a sophisticated culture of rational resource allocation.
Access the full publication [PDF format – 98 KB]
Renovation of Qanats in Syria [PDF format – 91 KB]
J. Wessels and R.J.A. Hoogeveen. Paper presented at the UNU/UNESCO/ICARDA international workshop ‘Sustainable Management of Marginal Drylands, application of indigenous knowledge for coastal drylands’, September 2002
This paper describes the research and action undertaken by an international research team at the International Center for Agricultural Research in the Dry Areas (ICARDA) that conducted a nation-wide survey of Syrian qanats in 2001. Within the framework of the United Nations University (UNU) project on traditional water management, some of the most important qanats sites were re-visited in August 2002. It was found that some have considerably decreased in flow during the last half-year and are at the verge of extinction. Ironically, qanats that have been flowing for 1500 years have been drying up over the last 15 years. What is the benefit of this sustainable water supply system in this time of ecological farming, increasing environmental awareness and within a changing social and economic environment?
Access the full publication [PDF format – 91 KB]
LINKS ABOUT QANATS
International Center on Qanats and Historic Hydraulic Structures
This centre aims to draw the attention of the world and especially those countries possessing qanats to the importance of this sustainable system, and encourage them to make use of this technique in their agricultural production system.
This website contains information on qanats history, distribution, equipment, famous qanats, documents and news.
Qanats section of the WaterHistory.org website
This section explains what qanats are, their history, construction, present-day systems, the urban layout, qanats as phreatic barometers, contemporary experiences with qanats, and the relation between qanats and diseases.
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