Karez
(Chinese 坎儿井 "Kan Er Jing"), a subterranean network of canals, is along with the
Great Wall and the
Beijing-Hangzhou Grand Canal as the three great engineering projects in ancient China. It was constructed in old
Turpan by the diligent people of different ethnic groups. They built it in accordance to the dry basin's natural environment, geography, solar radiation and circumfluent of air. By long period of practicing and building, Turpan people uniquely made use of the underground water in this harsh environment.
Turpan's karezes appeared in the late 18th century, they were distributed in the Turpan Basin, Hami and Helei areas. Turpan had the most subterranean canals, numbered over a thousand. If they are linked altogether, they will have reached 5,000 kilometers of total length. They are like fresh water wells, but local people adopted the technique that similar to that of Han Chinese, which cutting the earth and leading the abundant resource of underground water for daily use and irrigation in the arid basin.
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In addition to the human efforts, the water resources made by the melting snow from the mountains of Bogda (博格达山) and Kelawuchengshan (克拉乌成山) in every summer are essential to the forming of the subterranean canals. The water flows down to the basin area, it will penetrate the earth surface and eventually form underground streams. This process has a long history that the water accumulates which provides abundant resource.
Although reservoirs and man-made rivers have been built in the Turpan Basin for people's daily needs, the Karezes are still playing a vital role to make great contribution to local agriculture.