Kanerjingkaizaojiyi
01 · Historical Records
The name 'karez' (kan'erjing) came originally from the general term for water-diversion works in the Western Regions; in their long practice in the Turpan and Hami areas the ancestors turned it from a single trick of sinking wells to draw spring water into an underground canal project that strings beads into a line. The spacing of the vertical shafts is determined by the gradient of the underground channel: where the slope is steep the shafts are close together, where the slope is gentle they are far apart. The advance or retreat of the underground channel depends entirely on the direction in which the water runs through the rock strata, and the direction of excavation must accord with the height of the aquifer, so that one section after another can be joined to the outlet. Together with the carving of Buddhist cave shrines it belonged to one great undertaking; the selection of springs, the determination of the form, the opening of the channel and the preparation of tools were all explored and settled over many years of practice and gradually became a set of local methods that could be taught and learned, and to this day they are still passed on between masters and apprentices at the wells.
02 · Core Techniques & Process
The karez was called 'jingqu' (well channel) in ancient times. The karez excavation craft is a distinctive underground water-conservancy project created by the working people of all ethnic groups in Turpan, Xinjiang, through long production practice in accordance with the characteristics of the basin's geographical conditions, solar radiation and atmospheric circulation, using the ground gradient to divert groundwater. The karez excavation craft is mainly distributed in Turpan, Hami and other places in Xinjiang, and is most representative in Turpan City, mainly in extensive rural areas such as Ya'er Township and Putao Township. A karez generally consists of four parts: vertical shafts, an underground channel, an open channel and a pond (storage reservoir). People begin by digging horizontally upstream from the zone where groundwater overflows in the basin, entering the water-bearing stratum and extending as far as possible; the groundwater in the water-bearing stratum continuously seeps into the underground channel and flows out along it. Excavating a karez requires 3 to 5 people; during construction they work in groups of three (1 to 3 people digging the underground channel at the bottom of the shaft, 1 person hauling earth up at the shaft mouth, 1 person dumping earth outside the shaft, and 1 person driving the ox). Among these, the vertical shaft is rectangular; it is mainly the passage by which the digging personnel go up and down when cutting and repairing the underground channel, and it also serves to bring out earth and to provide ventilation and light, and it is relied upon to determine the gradient and direction of the underground channel and to carry out inspection and maintenance afterwards; the underground channel is a channel dug underground for several kilometres to twenty or thirty kilometres. Its function is to collect and convey groundwater to the surface; the open channel is basically the same as an ordinary channel, with a mostly trapezoidal cross-section, a small gradient and a slow flow rate. The junction where the water-conveying gallery meets the open channel is called the 'dragon's mouth' (longkou), and below the dragon's mouth the open channel begins; the pond (storage reservoir) is located at the end of the open channel, and the water drawn out is first stored in the pond and, after being left to settle and air, is used to irrigate farmland. Its technical characteristics are that the flowing water is not easily polluted and its temperature is stable, making it suitable for drinking by people and livestock; the construction process is environmentally friendly, causing little damage to the ground surface and little soil erosion, thus protecting the natural ecological environment. The karez excavation craft has a long history. The karez is of great significance in the history of Chinese water conservancy; using this craft a great deal of wasteland was reclaimed and oases were formed, and at the same time it is of great significance for improving the local ecological environment and regulating the microclimate.
Sinking shafts to fix the line
The line is surveyed on the surface and shafts are sunk one by one; the line between the shaft mouths gives the alignment of the tunnel, the difference in their levels gives its gradient, and the shafts also serve for spoil, air, light and later inspection.
Horizontal excavation of the tunnel
Tunnel driving stays level and forward within the water-bearing layer: one man loosens soil with short picks, it is passed up in wooden trays to the shaft mouth and tipped outside, and the work never pauses as they inch forward.
The dragon's mouth joining tunnel and open channel
Where the tunnel reaches the surface the gallery meets the open channel at the dragon's mouth, the critical node where level and flow must be equalised so the water neither floods nor silts up before the channel widens.
Settling ponds, sunning and distributing the water
Water from the dragon's mouth is stored in a settling pond at the end of the open channel and sunned before distribution, which keeps silt out and lets the farmer control irrigation timing.
03 · Regional Records & Related Items
Through centuries of practice in clearing silt and digging springs, the ancestors gradually formed a whole set of locally suited methods for the karez, including the selection of the spring flow, the shape and structure, the excavation method and the choice of digging tools.
04 · Cultural Value & Contemporary Safeguarding
This craft has all along been transmitted from master to apprentice. The karez excavation craft is a rare and precious cultural heritage left by the working people of ancient China, and possesses considerable historical, cultural and scientific value.
06 · Authoritative Sources & Bibliography
Sources
China Intangible Cultural Heritage Network (ihchina.cn)
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