NARRATOR: In Western
China, another engineering wonder is more understated. This is Turpan, home
of the Uyghur people. It’s a dry and
desolate area spotted with odd-looking mounds. Those bumps are
actually wells that lead to an ancient irrigation
system called the karez. Beneath the surface, more
than 1,000 vertical wells stretch down to canals. Using gravity, the
canals carry water from the rain-soaked
mountains to the desert. The underground canals
prevent the water from evaporating
while the wells give people access to the water. Today, this system
nourishes an area called Grape Valley, once an
oasis for weary travelers along the Silk Road. But maintaining the ancient
system is difficult and risky. TRANSLATOR: I have been
doing this for 10 years. The first time, it
was quite scary. But after a while,
I got used to it. NARRATOR: Workers regularly
descend into the wells to dredge out sediment
and stabilize the walls. TRANSLATOR: It is
important to do this. If we don’t, the
canals will dry up, and the village will
not have drinking water. NARRATOR: The canals provide
drinking water to thousands and irrigate 30% of the
crops in the region. Some of these grape fields
date back to the third century. The scale of production here
is best revealed from the air. Farmers use these mud brick
blocks to dehydrate millions of grapes and make raisins. It’s another ingenious
example of people working with mother nature.