Karez Irrigation System



Karez is a unique irrigation system mainly distributed in Turpan district in Xinjiang Uighur Autonomous
Region. It is reputed as one of the three major construction projects in ancient China, together with the
Great Wall and the Grand Canal. The history of it can be traced back over more than 2,000 years ago.

In Xinjiang, the greatest number of karez wells are in the Turfan Depression, where today there remain
over 1100 karez wells and channels having a total length of over 5000 kilometers. Turfan is located in
the second deepest geographical depression in the world, with over 4,000 square kilometers of land
below sea level and with soil that forms a sturdy basin. Water naturally flows down from the nearby
mountains during the rainy season in an underground current to the low depression basin under the
desert. The Turfan summer is very hot and dry with periods of wind and blowing sand. The water from
the underground channels provides a stable water source year round, independent of season.

Turfan's karez water system is made up of a horizontal series of vertically dug wells that are then linked by underground water canals to collect
water from the watershed surface runoff from the base of the Tian Shan Mountains and the nearby the Flaming Mountains. The canals channel the
water to the surface, taking advantage of the current provided by the gravity of the downward slope of the Turfan Depression. The canals are mostly
underground to reduce water evaporation.

The karez skillfully makes use of the geological conditions in the Turpan Basin, radiation from the sun and the atmosphere's circumfluence to form
a fascinating agricultural landscape. You can see the performance of the irrigation to find out the intelligence and diligence of Chinese people
thousands of years ago.

There are more than 1400 Karez wells in Turfan. But the number of the karez is much smaller than it was 50
years ago. The old Karez system is in danger of drying out due to over-use of underground water. To rescue
the endangered wells, the local authority has taken steps to restrict the exploitation of underground water,
and to protect the wells through modern technology. People hope the old Karez system will continue to
irrigate the oasis in dessert, and allow this miracle to live on for generations to come.