Historical documents show that the sinking method of the Karez wells inside Xinjiang including the Western Region was introduced by the Han people. The majority of the ethnic minorities of the northwest borderland hadn't mastered the sinking technology by that time. It was Lin Zexu that stood out among all the people who advocated and promoted the Karez wells as the most powerful and influential one in modern times. Ever since then the Karez wells have been part of the irrigation works.
The Karez wells in the Turfan area totaled up to over 1100 sets, among which 538 sets are in Turfan city, 418 sets in Shanshan and 180 sets in Toksun. The annual runoff volume of these Karez wells amounts to 294 million cubic meters which accounts for 30% of the total irrigated areas in Turfan area.
The length of the Karez wells varies with the geographical environment. A Karez well generally consists of four parts: the open channel, the underground channel, the vertical well and the small reservoir. The underground channel constitutes the main body of the system, which is in fact the underground watercourse. The vertical well functions as the outlet for the shipping out of mud and gravels. The water outlet of the underground channel is called "dragon mouth", which is in connection with the open channels above ground. The water of the Karez wells empties into the small reservoir before it is drawn into the channels.
Justification of Outstanding Universal Value
As for the criterion (i):
Karez wells are a successful application of the sinking technology of the Central Plains in the Turfan area. It is a historic inheritance and promotion of the sinking technology of the Central Plains, and plays a very important role in the study of the sinking technology both in the Central Plain and in the Middle and West Asia.
As for the criterion (iv):
There are more than 1400 Karez wells in Turfan. The total length amounts to more than 5000 km with an annual runoff volume up to 300 million cubic meters, surpassing the total runoff volume of the Flaming Mountain water system. Karez well can realize irrigation by water flowing automatically, which means low cost in running the system. It reduces evaporation, and avoids contamination caused by sand storm, to ensure the regular flow of irrigation water. It is stable in runoff volume and good in water quality to meet the standard for drink and irrigation. The technological requirement for the construction of the Karez well is not very high, and there is no lining for protection. The cover material is very simple and handy in local places with rather low cost. The total length will surpass 4400 km which is longer than the Yellow River, which is the "cradle river".
As for the criterion (v):
In the oasis of Turfan, Karez wells nourish the crops, nurture the people in this oasis and provide water sources for the passing merchants who are traveling through the great desert.
As the great irrigation project initiated by the ancient people, it is a great undertaking which benefits both the contemporaries and later generations.
Satements of authenticity and/or integrity
As an ancient irrigation system, the Karez well system has ever played a very important role in the daily life and in the production of the people in Turfan area. Though there is highly advanced electromechanical irrigation system, the function and position of the Karez system can not be superseded completely. On May 25, 1993, the 3rd Session of the 4th Standing Committee of Turfan Municipal People's Congress proved Provisions on the Administration of Turfan Karez Wells. It can be seen that its authenticity and integrity can be well preserved in the future.