Karez Wells

　　Karez wells, along with the Great Wall and the Beijing-Hangzhou Grand Canal, are known as one of the three great ancient engineering projects of China. There are nearly a thousand karez wells in Turpan, with a total length of about 5,000 kilometers. The structure of a karez well generally consists of four parts: vertical shafts, underground channels, surface canals, and a “lao ba” (small reservoir). In the Bogda Mountain range to the north and the Kalawucheng Mountain range to the west of the Turpan Basin, large amounts of snowmelt and rainwater flow down the valleys during spring and summer, seeping underground into the Gobi Desert. People ingeniously utilized the mountain slopes to create the karez system, channeling underground water flow to irrigate farmland. Because the karez system is not affected by heat or strong winds, there is minimal evaporation, ensuring a stable water flow that allows for gravity-fed irrigation.

　　Karez wells were recorded as early as in the “Records of the Grand Historian” (Shiji), where they were referred to as “jing qu” (well canals). Most of the existing karez wells in Turpan were built successively from the Qing Dynasty onwards. Today, they still irrigate vast areas of oases and fertile farmland. The Wudaolin Karez Well and the Wuxing Township Karez Well on the outskirts of Turpan City are open to visitors for tours. The name “karez” is called “karezzi” in the Uyghur language of Xinjiang. In Persian in Iran, it is called “kanatz.” In Russian in the former Soviet Union, it is called “kanyaliz.” Although these names differ phonetically, the differences are minor.

　　In the Chinese spoken in Xinjiang, China, it is called “karez” or simply “kan.” In various provinces across mainland China, it is referred to by different names; for example, in Shaanxi it is called “jing qu,” in Shanxi it is called “shui xiang,” in Gansu it is called “bai yan chuan jing,” and in some places it is also called “underground canal.”

　　The karez well is a very ancient type of horizontal water collection structure used for tapping and utilizing groundwater, suitable for foothills and alluvial fan fringe areas, mainly for intercepting groundwater to irrigate farmland and supply residential water use.

　　According to statistics from 1962, there were approximately 1,700 karez wells in Xinjiang, China, with a total flow rate of about 26 cubic meters per second, irrigating an area of about 500,000 mu. Most of these karez wells are distributed in the Turpan and Hami basins. For example, the Turpan Basin alone has about 1,100 karez wells, with a total flow of 18 cubic meters per second, irrigating 470,000 mu, accounting for 67% of the basin’s total cultivated land area of 700,000 mu. They hold significant importance for developing local agricultural production and meeting residents’ daily needs.