DRH-Asia: Disaster Reduction Hyperbase
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1. Title

Karez Technology for Drought Disaster Reduction

ID: DRH 45 Small Reservoir.
Hazard: Drought , Desertification , Climate change impact , Land degradation
Category:

Transferable indigenous knowledge (TIK)

Proposer: Weihua FANG
Country: CHINA;
Date posted: 30 December 2008
Date published: 16 March 2009
Copyright © 2009 Weihua FANG (proposer). All rights reserved.

Small Reservoir.

Contact

Weihua FANG (Associate Professor), Fei HE (Phd. Candidate), Hong CHENG (Master Candidate)
Academy of Disaster Reduction and Emergency Management, MOCA & MOE, China; Beijing Normal University
No. 19 Xinjiekouwai Avenue, Haidian District, Beijing, 100875, China.
E-mail: fang@ires.cn
Tel: 86-10-58802283
Fax: 86-10-58802158

2. Major significance / Summary

Karez is a traditional irrigation water system with a long history in Xinjiang area of China which makes use of underground water efficiently. As a comprehensive system, Karez is primarily made up of vertical wells, underground canals, a surface canal and small reservoirs. It is still being used to supply water resources for irrigation, domestic uses and others.

3. Keywords

Karez, Drought, Irrigation.


II. Categories

4. Focus of this information

Transferable indigenous knowledge (TIK)

5. Users

5-1. Anticipated users: National governments and other intermediate government bodies (state, prefecture, district, etc.) , International organizations (UN organizations and programmes, WB, ADRC, EC, etc.) , Experts , Teachers and educators , Architects and engineers , Urban planners , Rural planners , Environmental/Ecological specialists

5-2. Other users: Local residents

6. Hazards focused

Drought , Desertification , Climate change impact , Land degradation

7. Elements at risk

Human lives , Infrastructure , Rural areas , Mountain slopes , Agricultural lands , Others

Livestocks and household assets


III. Contact Information

8. Proposer(s) information (Writer of this template)

Weihua FANG (Associate Professor), Fei HE (Phd. Candidate), Hong CHENG (Master Candidate)
Academy of Disaster Reduction and Emergency Management, MOCA & MOE, China; Beijing Normal University
No. 19 Xinjiekouwai Avenue, Haidian District, Beijing, 100875, China.
E-mail: fang@ires.cn
Tel: 86-10-58802283
Fax: 86-10-58802158

9. Country(ies)/region(s) where the technology/knowledge/practice originated

CHINA;

In Turpan depression, Northwest of China, in Xinjiang Aera.

10. Names and institutions of technology/knowledge developers

Karez Irrigation System is developed through community practices over time.

11. Title of relevant projects if any

The similar irrigation systems have been used in Iran and Afghanistan.

12. References and publications

1. SI Maqian, SHIJI (historical records), 91 B.C.
2. Shouyi BAI (eds.), General history of China, 2004, Shanghai People Press.
3. Xingqi ZHONG and Huaizhen CHU (eds.), Turpan Karez system, Xinjiang University Press, Page 5~19, 1993.
4. Ji ZHAO, Geography of China, 2001, Higher Education Press.
5. http://it.chinahw.net/homepage/2006/baman/homepage/08xinjiang/01xinjiang/01.htm .
6. http://www.travelchinaguide.com/attraction/xinjiang/turpan/karez.htm .
7. www.karez.org .
8. http://blog.cersp.com/2005/11/06/165519.jpg

13. Note on ownership if any


IV. Background

14. Disaster events and/or societal circumstances, which became the driving force either for developing the technology/knowledge or enhancing its practice

Turpan is very dry in all seasons and very hot during spring, summer and autumn. The highest temperature recorded is 47.7°C in summer. The annual sunshine duration is about 3,100 hours. High temperature and strong solar radiation result in high annual evaporation amounting to 2800~3000 mm. Turpan is in an inner land with total annual precipitation of only around 16~17mm. Because of strong evaporation or the evapotranspiration process, precipitation (rain or snow) falling on the slope of the mountain would evaporate or seep underneath sand and soil before it can converge into a stream and reach the flat agricultural area along the foot of the mountain. Surface water is scarce in most areas. Under such tough circumstances, few plants or animals survive.

 


V. Description

15. Feature and attribute

1.   Support by Earth’s Gravity. Since Karez takes advantage of topography to divert deep subsurface flow through an underground canal to land surface for gravity irrigation, the cost for water-lifting equipment and its maintenance are almost negligible.

2.   Stable Outflow. The major water sources of the Karez system are melting snow and underground water. The underground canal can minimize high evaporation in the windy Turpan district hence, the impact of climate change is small. In addition, problems with sand blast can be avoided in the underground canal. All this makes the Karez system able to provide stable water resources, though total water volume may not be very large. As observed, there is a very stable population regardless of environment changes for thousands of years in Karez areas.

3.   High Water Quality. Melting water from snow infiltrates and the soil provides a very good filter to remove polluted materials. Unlike water channels on land, the underground canal minimizes water pollution and at the same time is rich in minerals. The water quality is suitable for drinking and domestic use.

4. Construction with Simple Tools. Most Karez systems were built with simple tools and do not require complex equipment.

16. Necessary process to implement

Karez is a traditional irrigation water system with a long history in Xinjiang area of China which makes use of underground water efficiently. Where farmland is located in the mountainous area, it is built on an alluvial fan or plain. The structure of a complete Karez system can be complex but its basic structure is essentially composed of vertical wells, underground canal, surface canal, and small reservoirs.

1.       Vertical wells. The major functions of vertical wells are for ventilation, proper orientation of the canal during construction and examination and repair of canals after construction. Besides for digging canals, vertical wells are also utilized to take out water from underground canals after the whole Karez system is completed. An aerial image of vertical wells is presented below.

2.       Underground and Surface Canals. The majority of the canals are underground. The canals under the surface are generally a network of canals in order for underground water to accumulate (left image). When the underground canal reaches the farmland, it becomes a surface canal and is linked to a small reservoir or directly connected to a system of water channels for irrigation (right image).

Small Reservoir .Water resources are collected in small reservoirs which can be adjusted for water level and temperature. Constructing reservoirs increase the water level as well as temperature so that a larger area of farmland is irrigated.

17. Strength and limitations

The strength of Karez Technology are 1) collect waters from rainfall and melted snow, 2) provided stable water resources and 3) high quality water. As a result, it reduced drought disaster effectively.  

On the other hand, the limitations of this technology are 1) cost is too high, 2) building time last several decades and 3) demand of manpower is more than thousands.

18. Lessons learned through implementation if any

Karez Irrigation System is a great result and enormous project of the ancient Chinese people. Although building time must be shorter to construct by modern instruments at present, the cost is still highly.


VI. Resources required

19. Facilities and equipments required

A variety of simple tools can be utilized in building Karez systems, such as excavating hoe, planning hammer, basket, winch, and oil lamp. The excavating hoe and planning hammer are used for digging passages underground. The basket and winch are used for carrying soil and sand. Iron oil lamps with an arrow for orientation are used for digging underground canals. The lamp can also be conveniently fixed on canal walls.

Here are the pictures of equipments:

(a) traditional oil lamp with side-arrow, (b) excavating hoe, (c) basket, and (d) a modern sheave used in building Karez system.

20. Costs, organization, manpower, etc.

For Karez Technology is a famous system engineering in the world, consequently, costs are too high and the time of constructions continue many years. Furthermore the demand of manpower is much higher and continued for decades.


VII. Message from the proposer if any

21. Message

Karez Irrigation System is the great gift from Chinese Ancients. Karez provided an effective way the elemental resources of human lives. In the modern day, how to used other scientific technologies to building and maintaining is the new challenge of us.


VIII. Self evaluation in relation to applicability

22. How do you evaluate the technology/knowledge that you have proposed?

It is a technology/knowledge that

23. Notes on the applicability if any


IX. Application examples


X. Other related parallel initiatives if any

Message


XI. Remarks for version upgrade

Message

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