Karez Underground Irrigation System
Illustration 2. Schematic of a Karez Project
- (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.
Flaming Mountain is situated in the north of Turpan Basin . Along the Turpan-Shanshan road there are red mountains about 100 km long. These mountains stretch in a east-west direction, and are about 10 km wide from south to north and 500 m above sea level. The highest peak is 850 m in height. The mountains are mainly composed of red sandrock. In summer, it is very hot here and under the hot sun, thermal air current rises, and the red sandrock gives out red light just like fire, so the mountains are named Flaming Mountains . Here is the hottest place in our country with the summer air temperature reaching 47 ? , and it was said that at the top of the mountain the air temperature is as high as 80 ? . Among the local ethnic groups spreads a fairy tale: there was a evil dragon that ate children. Later, the dragon was killed by a hero. Before killed, the dragon flew around the mountains that were dyed red by blood from the wound of the dragon.