The number of the wells of a 2,000-year-old irrigation system in
Xinjiang
Uygur Autonomous Region has reduced from 1,784 to 614 during
the past half-century, according to local water resources
department.
The karez system, a network that uses underground channels to
tap and distribute water using only gravity, is still in use.
"Declining groundwater levels mainly caused by the sharp rise of
motor-pumped wells should be blamed for the ongoing disappearance
of the ancient irrigation wells," said Wupur, general secretary of
the Xinjiang Karez Research Association.
Since the 1950s, 1,170 karez have dried up and the amount of
water they provide annually has decreased by 381.4 million cubic
meters. As a result around 190.5 thousand mu (12.7 thousand
hectares) have been cut off from the irrigation system, according
to Wupur.
With 23 karez disappearing each year, the system established by
local people so long ago will die out in 20 to 25 years without
effective protection from local government, said Wupur.
The history of the karez, which have mainly been used in the Hami
and Turpan areas of Xinjiang, where it is hot and dry, dates back
to the Han Dynasty (206 B.C. - 220 A.D.). It is considered one of
the three great projects of ancient China, along with the Great
Wall and the Beijing-Hangzhou Grand Canal.
The karez system consists of four parts: a hole as deep as 50 to
60 meters, an underground canal, an aboveground canal and a small
reservoir. It has many advantages, such as little evaporation from
season to season and little percolation, and can provide a stable
water supply that does not consume energy or cause pollution.
Wandering underground over 5,000 kilometers, the system has also
been called "the underground Great Wall."
?
(Xinhua News Agency December 20, 2004)
