Miracle in Xinjiang: Turpan

Grapes are one of the best known products of Turpan. The grape trellises run for hundreds of meters.
Photo courtesy of: www.yamaha-motor.co.jp/

URUMQI, March 23 (Xinhua) -- Yasin Nuyos and his co-workers crouch in a tunnel three or four meters underground shifting silt in the dim light of a lamp. Sweat flows freely even though the daytime temperature in early spring still hovers below freezing.

The team, largely consisting of Uygurs in Turpan, northwest China's Xinjiang Uygur Autonomous Region, are preserving a 2,000-year-old network of more than 600 "karezes", or subterranean irrigation canals, that channels water from the snow-covered Tianshan Mountains to cropland and solve the drinking water shortages in the arid region.

The locals owe a lot to the karezes that help the arid Turpan Basin find fame as China's leading grower of grapes and sweet melons.

The network of wells and underground irrigation tunnels extends more than 5,000 kms and are found mainly in Turpan, Hami and Hotan. Dubbed "the subterranean Great Wall", it is one of the three landmark projects left by Chinese forefathers - the other two being the Great Wall and the Grand Canal linking Beijing and Hangzhou.

The oasis at Turpan, located in the desert expanse of northwestern China (PRC), owes it surprisingly lush green environment to the karez (a.k.a. qanat) system of water supply. The basin surrounding Turpan has been the long-time haunt of the Uyghurs (a mixed Turki-Mongol ethnic group that is the majority in Xinjiang Province). The Turpan area is historically significant because nearby Gaochang (now a ruin) was once the Uyghur capital and an important staging area on the Silk Road.

Turpan lies in the second deepest inland depression in the world, with more than 4,000 sq. kilometers of land situated below sea level. Anciently called, 'Land of Fire,' it has recorded some of the hottest summer days in China, with temperatures as high as 130 degrees F.

Mildred Cable and Francesca French, two intrepid missionaries who spent many months in the region during the 1920s and '30s, describe the oasis vividly in their book The Gobi Desert (1942) as quoted in Foreign Devils on the Silk Road, p. 113:

. . . Turfan lies like a green island in a sandy wilderness, its shores lapped by grit and gravel instead of ocean waters, for the division between arid desert and fertile land is as definite as that between shore and ocean. Its fertility is amazing, and the effect on the traveller, when he steps from the sterility and desiccation into the luxuriance of Turfan is overwhelming.

The area's specialty is grapes, and many farms have drying towers for turning them into raisins. Turpan's greenery owes its existence to the underground karezes. These underground tunnels rate as one of Asia's more intriguing and historic public works activities. Uyghur and Chinese versions of karez technology date back over 2,000 years ago.

Karez
A karez is a horizontal underground gallery that conveys water from aquifers in pre-mountainous alluvial fans, to lower-elevation farmlands. The water for the karez is provided by the mother well(s), which is sunk into the groundwater recharge zone. A karez transports water underground, usually surfacing in cultivated areas. Putting the majority of the channel underground reduces water loss from seepage and evaporation. A karez is fed entirely by gravity, thus eliminating the need for pumps.

(1) Infiltration Part of the Tunnel
(2) Water Conveyance Part of the Tunnel
(3) The Open Channel
(4) Vertical Shafts
(5) Small Storage Pond
(6) The Irrigation Area
(7) Sand and Gravel
(8) Layers of Soil
(9) Groundwater Surface

Several theories have been made concerning the origins of Turpan's karez technology. It was: (1) imported from Persia; (2) locally developed and refined through long-term experience; and (3) developed elsewhere in China and then imported (ie. Longshouqu Canal project). Some combination of 1 and 2 seem the most probable. In seems likely that the karez concept moved north and east from Persia along the Silk Road.

In 1845, Lin Zexu was banished to the Turpan area. He was deeply impressed by the karez technology and encouraged its spread to other areas. Under his leadership more than 100 karezes were constructed. Statistics for 1944 show that there were 379 karezes in the Turpan area. By 1952, there were 800, with a total length of 2,500 km, equivalent to the length of the Grand Canal. Today there are over 1000 karezes in the Turpan area.
source: WaterHistory.org