Karez Well System
Natural Geographical Conditions
Why Karez Wells were built in great number in Turpan Basin can be attributed to the local natural geographical conditions. To the north of Turpan Basin is Bogda Mountai. In summer, large amounts of snow-broth and rainwater flow into Turpan Basin and infiltrate into the ground, and constitute underground current, thus making an adequate water source under ground for Karez Wells. Earth in Turpan Basin is solid and good for building well and underground channel. In Turpan it is very dry and hot in summer, and land here has a high evaporation rate. In wind season, the strong wind here can blow sands into every corner here. After wind, a lot of farmland and water channels are buried by sands. But Karez Wells can supply waters through underground channels and is independent of the effect of season and wind and sand. In addition, Karez Wells have a very low evaporation rate and a stable supply of water, and can irrigate farmland all the year round.
The word “Karez” means well. Karez Well is composed of four parts: vertical hole, underground channel, aboveground channel and water storage dam. It is built this way: first, to find water source in a place where there is underground water current, second, dig out vertical wells with certain distance in between, then, to build underground channel connecting these wells and thus water will flow through the underground channel. The outlet of underground channel is connected to the aboveground channel and thus underground water can flow out and irrigate farmland through the aboveground channel.
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there is highly advanced electromechanical irrigation system, the function and position of the Karez system can not be superseded completely.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.